June 6, 2017 Volume XIII No. 4

Fruit Bud Stages

In the Durham area on June 5^th, McIntosh and Cortland apples both had some fruit at 3/4 inch size. Peaches: fruit size 3/4 inch. Blueberries: bloom almost over. Raspberries: bloom. Grapes had flower buds visible, shoots up to 18 inches long.

Apple Scab

The primary apple scab season is over for much of the southern part of New Hampshire. If you are using the NEWA system data from a site close to you, it should predict the end relatively  accurately, provided that you had correctly entered the apple scab biofix (date when 50% of McIntosh buds are at green tip). The primary season ends with the next daytime rain, after all the spores have matured. Ten days after the end of primary season is an excellent time to do a final assessment (we often call it indexing) to see how well you did at managing the primary phase of the disease. All the lesions resulting from ascospore infection should be visible by that time. If you find no or very few lesions, you can relax scab management for the remainder of the season, and focus on bitter rot, flyspeck, sooty blotch and others. If you find a significant number of scab lesions, you may wish to make two back-to-back captan treatments to “burn out” those spore-producing lesions.

As a test, on June 2^nd I looked at the NEWA data for Ossipee, and used April 14^th as the date of green tip. That is two days later than we observed at the UNH Kingman farm in Madbury, and was my best guess for Ossipee. The model then predicted that all ascospores were mature June 1^st, and primary season would end with the next daytime rain after June 1^st.

Flyspeck and Sooty blotch of Apple

These “summer diseases” are caused by fungi that grow on the surface of the fruit, and on stems of LOTS of other hosts, including brambles, maples, wild apples & relatives. When the fungi grow on the surface of apples, they create cosmetic blemishes that lower the value of the fruit. So, many growers think about how to manage these fungi. They grow very slowly. The number of hours of leaf wetness after petal fall (I’ll abbreviate that & call it HLWAPF) is a critical measurement in managing the disease. Basically, we need 270 HLWAPF (if you are using old-style leaf wetness equipment) or 200 HLWAPF (of you are using the latest equipment) for each cycle of the fungus to grow and produce spores. We want to apply a fungicide that works on summer diseases at least once every cycle. In the early part of the year, we are usually focusing on apple scab, and often the fungicides we use also control summer diseases. We have the NEWA system to help monitor the weather. If you turn on your computer and visit the NEWA page for the weather station closest to you, it will predict where we are in the Sooty blotch/flyspeck cycle. First, it asks you to confirm the petal fall date for that site. For Durham/Madbury, petal fall on McIntosh was May 21-22. The model said that on June 2^nd, we had accumulated 132 hours of leaf wetness after petal fall. If you enter when your last fungicide was, the model will predict the risk level you have for summer diseases. By the way, fungicides that are really effective on summer diseases include materials like Cabrio, Dithane, Flint, Manzate, Inspire, Penncozeb, Polyram, Pristine, Sovran and Topsin-M. Remember to rotate fungicides between activity groups, to reduce the risk of the fungi becoming resistant to the fungicides.

Summer diseases show up especially on varieties that are light, such as golden delicious and gingergold. The growth is less obvious on dark red fruit. A low incidence of these is probably not a problem on pick-your-own blocks.

Got Cherries and Peaches?

I haven’t said anything about cherries this year, because things were so busy on the other fruits we grow. Brown rot can be a serious problem on cherries and peaches, and we have two phases where we focus attention. One is the blossom and shoot phase, mostly passed now. The second phase is attacking the fruit. Fruit become very susceptible as they begin to ripen. A second risk factor (especially for cherries) is splitting and cracking. This opens up infection routes for the fungus to attack. Bird attack also threatens when the fruit turn color. Are your bird protection methods ready?  The time will arrive before you know it.

San Jose Scale   

If you have a block of apples with SJS in them, you’ll probably want to consider making an insecticide application for the crawlers. The timing is important, and we use degree days to predict when the crawlers emerge. The NEWA system doesn’t currently include an SJS model, but it will compute degree days for you. You have to feed it information. It will need to know what base temperature you’re using [50F for SJS]. It will need to know the starting date (“biofix”). That’s when you captured your first SJS male in a sticky trap. Don’t use those traps?  Then substitute the full bloom date. We expect SJS crawlers to appear 310DD after full bloom. Usually that is in mid to late June.

Plum Curculio Time

Plum curculio attack is heaviest from the time apples are 6mm in size, through the next 3 weeks or so. PC is abundant enough and active enough to reduce your apple crop by 75 to 100%, if you do nothing to control it. The early injury (see my photo) looks like tiny c-shaped scars. Soon, the eggs laid in those scars hatch, the larvae bore through the fruit, and the affected fruit usually drop to the ground.

Blueberries: Mummyberry Disease and Fruitworms 

We had really good conditions for primary mummyberry infection this year. The risk of infecting the tiny green berries continues, and can be reduced by fungicide application. When bloom ends is the time to consider an insecticide for cherry fruitworm and cranberry fruitworm, both of which attack blueberries. Many plantings can go without this treatment, but some sites are prone to repeated attack. Both fruitworms are tiny caterpillars that bore inside the fruit. There are other caterpillars that eat the leaves, but most of them occur a little later in the year… usually July or August. One exception (on lowbush fields) is blueberry spanworm, which is feeding now.

Strawberry Clipper in Blackberries

I covered this tiny weevil in the last issue, and pointed out that it was attacking Strawberries and Raspberries. Blackberries are in perfect stage for attack as I write this, and the process is the same. The weevils hit the unopened flower buds. Damage is typically worst at the edges of a bed, especially bordering woods.

 Slime Mold  —  Yuck – In Strawberries

 We have had so much cool, wet weather this year, I’m anticipating that we will see a significant amount of slime mold this year. I hope it will get drier and I’ll be wrong. But in case that’s not correct, I’ll show a photo. Strawberry fields seem especially good places to find slim mold. Maybe it is our use of mulch that helps keep the soil at the right temperature and moisture for slime mold. Whatever it is, slime mold doesn’t actually attack the plant… it just grows over it. Typically it appears as blackish stubble growing on a nice, healthy green plant. It changes/moves quickly. Customers do not like it, and the best advice I can give is to assure them that it is not dangerous, and there’s not much we can do to avoid it.

Alan T. Eaton
Extension Specialist
Integrated Pest Management

UNH Cooperative Extension programs and policies are consistent with pertinent Federal and State laws and regulations, and prohibits discrimination in its programs, activities and employment on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sex, sexual orientation, or veteran’s, marital or family status. New Hampshire counties cooperating.

May 11, 2017 Volume XIII No. 3

Fruit Bud Stages

In the Durham area, McIntosh and Cortland apple fruit buds were at late pink stage on Monday morning May 8^th. A couple of king blossoms were threatening to open. Peaches still had petals… about 70% of the petals had dropped. Blueberries were at pink bud stage. Raspberries have some new primocanes emerging from the ground up to 4 inches high, and the very first flower buds were visible on the bearing canes.

Apple Scab

The largest ascospore releases during primary apple scab season usually occur around the time of pink or bloom. The rate of spore maturation is high then, and we have lots of exposed tissue available for infection. As of Monday May 8, the apple scab model forecasted 66% of the season’s spores were ready for release and 55% had already been released. Meanwhile, any spores that had started new infections this year have grown into lesions that soon will be producing conidia, which are infective spores that get spread by splashing. Conidia can be spread at night, but ascospores only get released by rains that fall during the daytime. You knew that, right?

Monitoring Leafminers in Apple Orchards

Not every apple grower sets out red sticky rectangle traps to monitor leafminer adults. For those who did not use the sticky traps, there is another way to monitor leafminer populations. It involves looking at the undersides of leaves, for the sap-feeding mines. You have to wait until about a week or so after petal fall for the mines to show up. They remain in this stage for perhaps a week to 10 days. So I’m showing this photo now, since I might not have a newsletter issue that comes out right at that time. Turn the leaf over and look at the undersides. Sap feeding mines show up as slightly silvery areas. Basically, the miners have severed the lower epidermis from the spongy palisade layer of the leaf. If you see 13  or more mines out of 100 CLUSTER leaves, it is worthwhile to apply an insecticide to control them.  Once the miners get bigger, they begin feeding on the spongy layer in little clusters. That creates spots that soon become visible on the upper side of the leaf. That signals the end of the period when the caterpillars are vulnerable to insecticides. By the way, in this photo I see 4 sap-feeding mines on the same side of the mid-vein as my thumb. In real life, tilt the leaf a bit, if you are unsure. Another trick is to use a pin or knife tip to try & peel away the epidermis. The tint, translucent caterpillar should be there somewhere.

Tent Caterpillars and Gypsy Moths

Both of these are common backyard tree fruit pests that are easily controlled if you act early. The larger the caterpillars get, the more damage they have already done, and the harder they are to control. There are actually two species of tent caterpillars, forest tent caterpillar and Eastern tent caterpillar. Both are easily controlled with Bacillus thuringiensis-based insecticides, but could use synthetic chemicals too. Not only are they easier to control when small, they have also done less damage then.

Gypsy moth is usually held in check by an insect-killing fungus. But the southeastern part of our state has experienced drought the last two growing seasons, so gypsy moths are building up there. Gypsy moths are tougher to kill with B.t.- based insecticides, but they work if the caterpillars are small… perhaps shorter than 1 inch. By the way… B.t.-based materials must be sprayed on the leaves the caterpillars eat. They do not work by contact action. Most chemical insecticides work both ways… both as stomach poisons and as contact poisons.

Insect Pest Activities in Apples During Bloom

Adults of codling moth begin laying eggs about the time of full bloom to petal fall. That’s also the same time that males of San Jose scale do their flying. Since a couple people are trying pheromone traps to monitor SJS this year, I include this old drawing of a male from a USDA bulletin over 70 years ago. They are only 1 millimeter (1/25 inch) long. For those of you monitoring SJS with these traps, the number of males you find is not very important. It is WHEN they appear, so I’d check my traps every day or two. That starts the clock ticking to predict crawler emergence by calculating degree days. What else is happening then?  Eggs of European apple sawfly are beginning to hatch. Lesser appleworms should start flying. Plum curculios should start moving into orchards, if the weather is favorable. They won’t begin attacking the fruit until the first fruit reach ¼ inch size. Then, they attack heavily, usually for about 3 weeks. They can totally eliminate your crop.

Mummyberry Disease of Blueberry

The fungal cups that I showed in the last newsletter produce ascospores that are released in rainy weather and infect young blueberry leaves. Now it is time to show the next part of the cycle. Those primary lesions (photo below) produce fungal spores that are splash spread and infect the green fruit. At first, there is no outward sign that the fruit are infected. But eventually they start turning a salmon color, and then start becoming ridged, like a pumpkin, and drop to the ground. The fruit stay on the ground all season, becoming black, dry and ridged. Then the following spring, fungi grow from them and the cycle repeats.

Blueberry Pollinators and “Cheaters”

Since the large carpenter bee reached New Hampshire a few years ago, we have seen more blueberry corollas with holes in the base. What’s going on?  Large carpenter bee has strong jaws, and often chews a shortcut to reach the nectar. That means that it doesn’t really contribute much to pollination, when it does this to reach nectar. Other bees don’t seem to do this. What can you do about it? Probably nothing, so don’t worry. Carpenter bee looks just like several species of large bumble bees (which are good blueberry pollinators by the way) except that it has a SHINY black abdomen.

Strawberry Clipper

This tiny (2mm long) weevil is also known as strawberry bud weevil. It overwinters as an adult, and usually appears in May, just as the first fruit buds of its major host plants (strawberries, raspberries and blackberries) are appearing. The female beetles attack the unopened flower buds by laying an egg inside. Then they sever the petiole, and that bud will never produce fruit. Damage is typically worst at the edges of a bed, especially if woodland is on that side. Sometimes we can see a significant amount of injury, and in other spots or other years, there is very little. If you look at the New England Small Fruit Management Guide, you’ll see a sampling procedure and thresholds to help you determine if it is worthwhile to treat a bed for this insect. It is worthwhile to do the monitoring, rather than guessing if there will be a problem… or just automatically treating.

Organic Weed Control in Lowbush Blueberries

My colleague Olivia Saunders finished a SARE grant on this subject, and recently placed a report you could read, if you’re interested. Bill Lord assisted setting up this project, which especially focused on poverty grass. Here is a link to that report https://extension.unh.edu/resources/files/Resource006566_Rep9432.pdf

We thought that lowbush people might like to learn more, so Olivia has set up a meeting at a lowbush site in Milton, on May 31^st. See the UNH Cooperative Extension events calendar for more details.

Raspberry Fruitworm

Do you ever find a small, tan, segmented “worm” in the raspberries you picked? Those are most likely raspberry fruitworms. Usually they are not a significant problem, but in some plantings there are a lot of them… enough to discourage customers. The problems from this insect begin early, and the adults are tiny (3mm) oval, tan beetles. They are active on opening raspberry and blackberry vegetation, and sometimes they chew up the opening fruit buds. If you see what you think are a significant number of them, you might consider applying an insecticide before bloom to kill them. After bloom, the females lay eggs inside the green fruit. The eggs hatch into the segmented tan larvae, which feed on the receptacle. When the ripe berry is picked, the larva often ends up inside.

Alan T. Eaton
Extension Specialist
Integrated Pest Management

UNH Cooperative Extension programs and policies are consistent with pertinent Federal and State laws and regulations, and prohibits discrimination in its programs, activities and employment on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sex, sexual orientation, or veteran’s, marital or family status. New Hampshire counties cooperating.

April 18, 2017 Volume XIII No. 2

Fruit Bud Stages

In the Durham area, McIntosh and Cortland apple fruit buds are mostly at half inch green stage, with a few buds still at quarter inch green. Peaches are at pink stage, with a few buds still at half inch green. Blueberry fruit buds have loose scales, with one variety at early tight cluster. Raspberries show ½ to ¾ inch of growth from the fruit buds.

Apple Damage Photograph

The photo used for the header in this year’s newsletter shows a certain type of injury to apples. Can you tell what it is?  I’ll reveal the answer later in the season.

Tarnished Plant Bug

A few growers still monitor for tarnished plant bug, using the white sticky rectangle traps (still available from Great Lakes IPM). The traps can tell you whether or not it is worthwhile to apply an insecticide for this insect. Place the traps at knee height, towards the tip of a low branch. Yes, that’s at KNEE height. The trap should be over a grassy (not bare) part of the orchard floor. I tend to hang them relatively close to the orchard periphery, but that’s not essential. When?  Hang at silver tip stage. Then you check them weekly and count (then remove) any tarnished plant bugs you catch. Some growers use these to compare differences block-to-block. I’d expect more TPB injury in a block that was adjacent to hay fields or clover, compared to one that was surrounded by woods.

There are several thresholds. For people with a strong market for #1 fruit (like pick-your-own growers), it is worthwhile to apply an insecticide for TPB if the cumulative catch (from silver tip to tight cluster stage) per trap is 5.5 or more by the time of tight cluster. If you haven’t reached that threshold by TC stage, keep the traps up and check again at late pink stage. The cumulative threshold from ST to late pink is 8 or more per trap.

If you are aiming for extra fancy fruit, the threshold is from ST to TC is 3.5 per trap, and ST through late pink is 5 per trap.

Identifying the insects: tarnished plant bugs are 3/16 inch long, with long, thin antennae. Overwintered adults are dark brown. The body is shield-shaped.

Monitoring Leafminers in Apple Orchards

We have two species of leafminers that are difficult to tell apart… apple blotch leafminer and spotted tentiform leafminer. Both can cause premature fruit drop, usually just as you are setting out bins in your McIntosh block. McIntosh is the variety most sensitive to this injury. We can monitor populations of these leafminers by two methods: red sticky traps or counting the tissue-feeding leaf mines. If you choose to use the traps, they need to go up soon. The red sticky traps are available from Great Lakes IPM www.greatlakesipm.com I’d place them in blocks where leafminers have been a problem in the past. Attach one at knee height to the south side of the tree trunk. Some growers use a stapler for this, while I use four push pins. When do you set them up?  Do this at green tip stage. Sometimes you can delay until ¼ inch green. The moths start emerging just after QIG stage, and you check the traps weekly for the tiny moths. Don’t check your traps over a longer interval than 1 week, or the insects will turn black and you won’t be able to identify them. Count and remove the moths each week. The moths are almost 2/16 inch long, with dark silvery marks on white, elongated wings.

In a McIntosh block, the threshold is 3-4 moths or more by early pink stage. In all other varieties, the threshold is 6-8 or more by early pink stage. If the leafminer population is below the threshold, I suggest that you NOT spray an insecticide for them.

These thresholds tell you IF it is worthwhile to apply a leafminer treatment. WHEN you treat is up to you. You have 2 generations that could be targeted, with multiple windows of opportunity before mid-summer. Generally, treating for the first generation is more effective than the second, because it is more synchronous than the second. I NEVER recommend treating for the 3^rd generation, because it is too late to prevent the fruit dropping, and the third leafminer generation is heavily parasitized by tiny wasps.

Winter Moth

Winter moth eggs hatch when the buds are opening, and the tiny caterpillars sometimes balloon into the edge of your orchard or blueberry planting, from adjacent oak or other trees. They are not very difficult to control, but timing is important. If your blueberries/apples are in the seacoast region, you have a greater risk of a problem than people who are located farther inland in New Hampshire. Make a note on your calendar to check for these insects, especially at the edges of your planting.

Eastern Tent Caterpillars

Eastern tent caterpillar eggs are in a shiny mass that usually encircles a twig. I rarely see them in conventional commercial orchards, but they are very common in organic blocks and backyard trees. Apples, cherries, peaches and pears seem to be the most frequently attacked. The insects are easy to control (even with Bacillus thuringiensis), unless you wait until they are huge. For many years I could accurately say that they hatched about April 15^th. In recent years, it has been significantly earlier. The tiny caterpillars feed on the leaves, and begin to construct a silk tent in a nearby crotch. In most orchards, they are controlled by insecticides directed at other insects. If you see the egg masses before they hatch, you can avoid damage to your tree by removing and burning the egg masses. Just peel them off the twigs. My photos show an egg mass in early March and some very young ETC caterpillars in April.

Apple Scab

The biofix (starting point) for the apple scab fungus spore maturation model is when 50% of the McIntosh buds have reached green tip stage. Really early in the season, there is relatively little host tissue that is exposed, and a small % of the season’s supply of spores that are ready for release. As the season progresses, more vulnerable tissue is exposed. Typically we have the largest spore releases around the period of pink or bloom stage. Then, the primary infection season winds down, often in early or mid-June. It ends because the ascospore supply gets exhausted, and the dead apple leaves from last year are breaking down. But the lesions that result from primary infection enlarge and start producing infective spores called conidia, which get spread by rain splashing. So we can have many cycles of the disease by the time the season ends. If growers get through primary season with few or no lesions, they can relax spraying quite a bit (for scab anyway) after that.

So, we are at the beginning of primary scab season, and growers need to think about if & when to apply a protectant fungicide. We want to apply the fungicide long enough before a rain so that the residue dries onto the leaves and fruit. Then, rain can come after that, and the fungicide can protect from any rain that falls. Generally, a good protectant fungicide that is allowed to dry onto the foliage will protect for 7 days, no matter how much rain falls. Occasionally we get real deluges that test this theory. There are also “eradicant” fungicides that can be applied after a rain, and they can stop an infection even up to X hours after the rain started. In some cases X is as high as 48 hours!  Of course, these tools are usually more expensive than the protectant fungicides. It is nice to know that they are available, so if your sprayer breaks down at a critical time, an eradicant fungicide can serve as a safety net.

As of Monday April 17, 4% of the season’s supply of ascospores were ready for release in the Durham area.

Peach Leaf Curl

It is too late to control peach leaf curl this year. You’ll have to live with it.

Cedar-Apple Rust and Quince Rust

In the last issue, I showed a photo of the galls on a red cedar tree during the quiet winter. Once spring arrives, things start to change. During rainy weather, orange, fleshy telial horns project from the galls, and release the telial spores that infect apple foliage. One co-worker said the galls looked like bright orange Christmas ornaments. I thought that was a good description. The very first spore releases are around the time of tight cluster stage, and the major releases are at pink and bloom period. Quince Rust shows a similar pattern, though the galls (which are on common juniper) are difficult to spot. They are swellings in the juniper branches. To me, they are almost impossible to find, except when the fleshy orange telial horns are projecting. This photo shows them on a common juniper in Durham, on a rainy May 9^th morning, 2013.

There are three ways to fight rust diseases on apples. One is to grow varieties that are not very susceptible to them. Another is to apply protectant fungicides during the period when spore releases are likely to occur. A third way is to remove all alternate hosts within 500 feet or so of your apples. With the exception of rusts that attack apple fruit, I don’t see enough injury to worry too much about them. The bright orange spots on apple leaves are easy to identify as rust lesions.

Mummyberry Fungus

Blueberries get attacked by fungi, too. The most serious disease I see is mummyberry, and the tiny fungal stipes should start growing from last year’s mummified berries (on the ground) soon. They begin as a dark brown stalk. Then the tip swells slightly, and a dimple appears at the tip, so it looks a bit like the head of a finishing nail. Then the tip expands still further into a tiny mushroom, and the color is light brown. These are the source of the spores that infect shoots this spring.

We manage mummyberry with several methods. One method is to bury last year’s mummies with at least 2 inches of mulch. That can be difficult to do if you have a large planting. You have to be sure you finish applying the mulch before green tissue appears (= before spores start getting released).

Another method is to apply a burning agent (urea) when the fungal stipes have started elongating, but before the fungal cups have opened. A third method is to apply protectant fungicides. For some growers with very small plantings, there is another option: Collect and deeply bury all fruit affected by this disease. The New England Small Fruit Management Guide has details on all of these options.

2017 Fruit-Related Events:

There are many events that might be of interest on our events calendar. Some events require registration or have fees, so you can see more details on our  events calendar.

Alan T. Eaton
Extension Specialist
Integrated Pest Management

UNH Cooperative Extension programs and policies are consistent with pertinent Federal and State laws and regulations, and prohibits discrimination in its programs, activities and employment on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sex, sexual orientation, or veteran’s, marital or family status. New Hampshire counties cooperating.

 

March 30, 2017 Volume XIII No. 1

Fruit Bud Stages

As I write this in late March, all fruit buds in the Durham area seem dormant: apple, peach, blueberry, raspberry.

NEWA Weather Station Setup & Info Retrieval

Some of you know that Cheryl Smith, Becky Sideman and George Hamilton wrote and received a Specialty Crop block grant last year from the NH Department of Agriculture, Markets and Food. The purpose was to bring NEWA [Network for Environment and Weather Applications] weather stations to New Hampshire. The money arrived well into the growing season, and by December 31, Cheryl Smith had received equipment and set up stations in six counties:

Belknap (Moulton farm, Meredith)

Carroll (County farm, Ossipee)

Merrimack (State forest nursery, Boscawen)

Rockingham (County farm, Brentwood)

Strafford (UNH Woodman farm, Durham)

Sullivan (Alyson’s orchard, Walpole)

There is already one NEWA site that Brookdale Fruit Farm (Hollis) bought and installed in their orchard earlier. There is another privately-owned system on River Road in Bridgewater. Cheryl hopes that the equipment will be set up in Cheshire, Coos, Grafton and Hillsborough counties by some time in April-May (depending on snow cover and frozen soils).

Why were those sites chosen? We wanted one site per county, a mix of county farms and growers, a mix of crops, and the sites must have certain data access and transmission requirements (basically, fast, reliable access to internet).

If you haven’t tried accessing information from these sites, you ought to try it now, before the growing season gets too busy. The six sites are up and running. In addition to seeing what the weather information was for your site(s) of interest, you can learn how many degree days have accumulated (set the biofix first) for various insect or pathogen models.

Last year we had significant problems with fireblight in New Hampshire orchards. The NEWA system has a FB predictive model to assess risk. Cheryl uses this information to send out alerts. A few NH orchards had codling moth problems last year. NEWA can predict when each codling moth generation begins, to help you determine when risky periods occur. Some of you would benefit from knowing when San Jose scale crawlers emerge. The site can predict that as well. Cheryl and Alan already use NEWA to look at apple scab risk.

To begin using the system, point your computer’s internet browser to NEWA’s home page www.newa.cornell.edu  On the screen you’ll see a map with lots of green “leaf” icons. Those are weather stations. Use the + and – buttons on the lower right of the map to enlarge or shrink the map, to find the sites of interest to you. (You could use an airport if that is nearby, but a station next to the tarmac might not be the best for some applications… like determining how long leaves were wet.)

Do you need to set biofixes?  Yes, for some models, you’ll have to do that. For example, last week when Alan clicked on the Durham station and selected apple scab, the system gave him the opportunity to enter the date for green tip stage. Since this was before green tip had occurred, he switched tasks and asked to look at the weather data. It has lots of options to explore.

Take a look, and we think you’ll find it easy and helpful

Written by Alan Eaton and Cheryl Smith

Higher-Than Average Gypsy Moth Numbers for 2017

Formerly, gypsy moth populations in New England followed rough cycles of highs and lows, with about 10 to 11 years between high points. Then the fungus Entomophthora entomophaga (a pathogen that hits mostly gypsy moth and other caterpillars in its family) took hold, and we no longer had enough gypsy moth caterpillars to cause widespread defoliation. But in really dry years, the fungus does poorly. So I anticipate that we will see some individual spots with gypsy moth buildup, especially in Rockingham and eastern Hillsborough Counties. That is, unless the rains return and knock down larval numbers in June. If you see the egg masses, that suggests you’ll have caterpillars this year. Egg masses should hatch in late April.

Another Prediction: High Peach Leaf Curl Incidence in 2017

We had almost no peach crop last year, so that means there were relatively few fungicides sprayed on peach trees last year. Those conditions cause an increase in problems with peach leaf curl. If done at the correct time, spraying certain fungicides (Bravo, C-O-C-S, Echo, Ferbam, Kocide, Badge, Ziram…) will control the disease. One time to have done that was last fall, at the time of leaf fall. If you did not make an application then, and you’ve had peach leaf curl problems before, you should consider a spring application this year, before bud swell. Sprays made shortly after buds started swelling might provide partial control. My photo shows the distorted, thickened & discolored leaves affected by peach leaf curl disease.

Prune off Peach Mummies?

I asked David Rosenberger if it was worthwhile to prune off peach mummies, while I was pruning my apple trees. I don’t have many, so it would be easy. He said that on the cruel, frozen tundra of New Hampshire, Brown rot fungus does not overwinter well in fruit mummies, so dropping them might help, but probably isn’t necessary.

Prune off Cedar-Apple Rust Galls?

The fungus that causes cedar-apple rust has to switch hosts each year. Spores from rust lesions on apple leaves infect redcedar, and spores from redcedar infect apples. So if you have a redcedar tree with galls on it, and you also grow apple varieties that are susceptible to the disease, it is worthwhile to remove & burn or bury the galls, before much apple leaf tissue emerges. But you may consider just cutting down the redcedar tree, especially if it is tall and has a lot of galls. Either way works to break the infection cycle. The manuals say that the spores from galls on redcedar can travel a long ways. If you grow susceptible varieties such as Gala, Golden delicious, Jonathan, Jonagold, Mutsu, Prima or Rome, we often suggest removing any red cedar trees (even tiny ones) within 500 feet of your apples.

Winter Moth

In New Hampshire, the seacoast region has the greatest risk of winter moth problems. Elsewhere, a close relative (bruce spanworm) is common, but rarely causes serious problems. Winter moth overwinters as eggs on trees (esp oaks, maples). The eggs turn blue just before they hatch. The tiny caterpillars that hatch out of the eggs feed on leaves, and often they spin out long strands of silk, and get blown into other trees & bushes nearby… like your apples or blueberries. The insects are not particularly difficult to kill, but they often escape our notice before they cause damage. Egg hatch usually occurs as buds are swelling open and the first tiny leaves are emerging.

Another New Insect

It has been a few months since we had an announcement about a new insect, so I guess we are overdue. A European fly that attacks cherries (wild and domestic) was detected in Missisaugua, Ontario in 2016. It is called the European cherry fruit fly. Yes, it is similar to our native cherry fruit fly, but has a slightly different wing band pattern, and a yellow dot on its thorax. To my knowledge it has not yet been found in the USA, but we have the climate and hosts for it to thrive in New England. For cherry growers, its appearance will change a few things. Our State Entomologist Piera Siegert and her staff at the New Hampshire Department of Agriculture, Markets and Food are planning to set traps for it at several NH sites this year. The insect hits mid and late season cherries, and prefers fruit that are in full sun.

2017 New England Tree Fruit Management Guide

We do not plan to print and distribute the 2017 guide. Instead, we have been working on creating an on-line version, which is mobile-friendly. I wrote a chapter on vertebrate pests, and George Hamilton wrote one on sprayer calibration. Our New England colleagues have been busy writing about pathogens, insects and other concerns. We hope that it will be ready for you and accessible soon. When it is ready, I’ll provide you a link. Until then, we’ll depend on the older version.

Just announced! The guide should be ready next week. Read it here: http://netreefruit.org

Fruit Pest Update Telephone

I plan to set up the first message March 28^th to 30^th, and expect to record a new message every Tuesday. Most messages last three minutes, but sometimes when things are really busy, one stretches to four minutes. The telephone number is unchanged (862-3763) and you can call it any time of day or night that interests you. As usual, I’ll cover fruit pest information and will include announcements of events that might be of interest. I’ll keep it running continuously through mid-September, possibly later. I started this service in 1979, when the NH fruit growers’ association purchased equipment to get it started.

2017 Fruit-Related Events:

There are many events that might be of interest on our events calendar. Among them are our usual mix of spring pruning demonstrations, some of which have already gone by. Some events require registration or have fees, so you can see more details on our events calendar.

Alan T. Eaton
Extension Specialist
Integrated Pest Management

UNH Cooperative Extension programs and policies are consistent with pertinent Federal and State laws and regulations, and prohibits discrimination in its programs, activities and employment on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sex, sexual orientation, or veteran’s, marital or family status. New Hampshire counties cooperating.

May 25, 2016 Volume XII No. 3

 Fruit Bud Stages

In Durham and Madbury, McIntosh apple buds were at fruit set on Monday May 23^rd. Blueberries were in bloom. Raspberries had many flower buds visible, but unopened.

Apple Scab

We usually expect the primary apple scab season to start winding down now, but will not end for a while… probably early June. It is a good time now to do a check for apple scab lesions, and it would be very important to do that again about 10 days after primary season ends. The 10 days allows enough time for the latest lesions to become visible.

Weather Data, Prediction Models

Although the riskiest time for fireblight has ended for some NH orchards, I’ll give links I have been mentioning at twilight meetings and orchard visits. They can help with a number of pest events. One is Glen Koehler’s Orchard Radar. This link takes you to the radar page, and there may be sites relatively close to you that are worth checking out. Groton Massachusetts or Sanford Maine may be relatively close to some NH growers.

A second source of information is NEWA, the Network for Environmental and Weather Applications. We have one NH orchard with a NEWA station, Brookdale in Hollis. You can view the data and predictions for fireblight, (and apple scab, curculio, potato late blight and lots of other pests). Look at the map, and enlarge it to find the icon for Hollis, then clicking on it to get predictions for that site. If you’re far from Hollis, another option (maybe not quite as accurate) is to click on an icon for a nearby airport, on the NEWA map. Eventually we hope to have more NEWA sites in NH. Funding for some of that equipment is anticipated soon. We’re still waiting to hear on a second grant proposal.

Plum Curculio: Most Important Apple Insect Pest?

Plum curculios overwinter as adults, in leaf litter in the woods. They become active about when apple blocks are in bloom. They heavily depend on odor to find apple trees. Once there, attack must wait until the fruit reach 6mm in size. Then the females cut a shallow curved scar into the fruit, and lay an egg under the flap. Fruit that are attacked usually drop to the ground, and in some spots there are enough curculios to attack nearly 100% of the crop. The larva hatches from the egg and tunnels through the fruit. When mature, it drops to the ground and pupates in the soil.

The attack period generally lasts about 3 weeks, but in sites with lots of nearby wild apples, it can extend longer. Basically, we use insecticides to control this insect. The insecticides are harmful to pollinators, plus parasites and predators of leafminers, aphids, caterpillars and mites. If we can minimize spraying, it helps preserve populations of these beneficial organisms and save money.

One way to minimize spraying is to wait to apply the first one until just before the first fruit reach 6mm size. Another option is to time your applications with the aid of a degree day model. My colleagues in New York developed one that some NH growers find useful… and others say it doesn’t work so well for them. It says to keep apples protected through 340 degree days (base 50) after petal fall. [By the way… petal fall in Durham was Friday May 20th. Did you write down your PF date?] We expect that some pesticide residue will continue to control them for a little while past that. This model doesn’t work too well in blocks with a history of heavy, long-lasting pressure. I would not rely on it completely, but it might help you determine when you can stop. In most blocks, three weeks after the first fruit reached 6mm size, there should be no significant immigration of new adults, and spraying can cease.

The insecticides we target for curculio also control the first generation of several other fruit-attacking insects: codling moth, lesser appleworm, and redbanded leafroller. They also control insects that rarely are a problem in commercial blocks, but can be serious in backyard trees: tent caterpillars, gypsy moths, winter moth, green fruitworms. The most effective for curculio: probably (alphabetically listed) Actara, Avaunt, Calypso, Imidan, Leverage and Voliam Express. The last two are combination products. For backyard growers, Sevin is probably the best alternative, in part because it is packaged in appropriate sizes. All-purpose fruit sprays are too drastically diluted to control curculio. For organic growers, Surround is the best choice, but it has to be applied very carefully to work properly. That means you need several thorough but dilute applications. Surround doesn’t kill them. It just interferes with their host recognition (and thus, attack).

European Apple Sawfly

This is now a relatively minor pest, but fruit that are attacked have a long, curved scar that greatly reduces the fruit’s value. EAS adults emerge from the soil during pink stage. The females are very active in the flowers during bloom. That’s when they insert their eggs singly into the tiny fruitlets at the calyx end. In a few orchards, growers have enough trouble with this insect that they apply an insecticide at pink to control it, knowing that the first curculio spray will also help. But in blocks that have varieties with a range of petal fall dates, that curculio spray is slightly late to stop some EAS damage. My data shows that the incidence of EAS injury at harvest in NH (25 year average) has been below 3/10^ths of 1 percent… so not very serious.

Blueberries: Mummyberry and Fruitworms

Blueberry growers take note: the fungal stipes of mummyberry fungus should be releasing ascospores now during rainy periods. The spores infect tiny opening blueberry leaves, where the fungus grows and produces conidia. The conidia are splash-spread spores, and they infect the fruit, while it is still green. At first, infected fruit are symptomless, but when ripening time arrives, they turn tan and shrivel up. Some of our varieties that are especially susceptible to the disease are Bluecrop, Blueray, Earliblue, Jersey and Berkeley.

We have two species of fruitworms that attack blueberry. One is called the cherry fruitworm, and the other is cranberry fruitworm. I see a lot of highbush plantings, and in a few of them there is enough fruitworm attack to consider an insecticide treatment. In most, the attack rate is so low, the cost of treatment is probably higher than the value of the damage it would prevent. If you do decide to apply an insecticide, the timing is right after bloom ends. Usually one treatment is enough. It is designed to kill the just-hatched caterpillars.

Clipper in Brambles and Strawberries

Strawberry bud weevil is also known as “clipper”, because it attacks the unopened flower buds of brambles and strawberries, then chews off the buds in which it laid an egg. There is only 1 generation per year, and they overwinter as adults. When flower buds are present but unopened (= NOW), that is when this insect attacks. Attack rate is usually the highest in the edges of the fields, and lower in the interior of the plantings. In strawberries there are thresholds established, and you can read about them in the New England Small Fruit Management Guide. Thresholds have not yet been determined for brambles. Notice in my blackberry photo that all of the brown fruit buds are the ones that have been attacked, and are dangling.

 

Alan T. Eaton
Extension Specialist
Integrated Pest Management

The University of New Hampshire Cooperative Extension is a public institution with a longstanding commitment to equal opportunity for all. It is the policy of UNHCE to abide by all United States and New Hampshire state laws and University System of New Hampshire and University of New Hampshire policies applicable to discrimination and harassment. It does not discriminate on the basis of race, color, religion, sex, national origin, age, veteran’s status, gender identity or expression, sexual orientation, marital status, or disability in admission or access to, or treatment or employment in, its programs, services, or activities.

 

May 3, 2016 Volume XII No. 2

 Fruit Bud Stages

In Durham and Madbury, McIntosh apple buds were in late tight cluster stage on Monday May 2^nd.  Almost all of our peach buds appear dead.  Blueberries are at pinkbud stage.  Raspberries and thornless blackberries are still ½ to 1 inch of growth from the buds.

Apple Scab

We are at the part of the season when we normally expect high numbers of ascospores to be ready for release, and there is a lot of susceptible apple tissue. That makes it a high risk period for apple scab. The spring has been fairly dry, and that might affect ascospore maturation, but for now, I’d assume the risk is high, whenever that next daytime rain falls.

Fireblight

As we approach the bloom period, remember that warm (60F or higher) rains when flowers are open means high risk for fireblight. We had a number of NH orchards with LOTS of FB strikes last year, so there is potential for a lot of inoculum being present. Remember that there are a couple of sources that run weather models to predict fireblight risk. It may be worthwhile to check these sites as we approach & enter the high risk time for FB. One is Glen Koehler’s Orchard Radar. There may be sites relatively close to you that are worth checking out. Groton Massachusetts or Sanford Maine may be relatively close to some NH growers.

A second source of information is NEWA, the Network for Environmental and Weather Applications. We have one NH orchard with a NEWA station, Brookdale in Hollis. You can view the data and predictions for fireblight, (and apple scab, curculio, potato late blight and lots of other pests) here. Look at the map, and enlarge it to find the icon for Hollis, then clicking on it to get predictions for that site. If you’re far from Hollis, another option (maybe not quite as accurate) is to click on an icon for a nearby airport, on the NEWA map. Eventually we hope to have more NEWA sites in NH. Funding for some of that equipment is anticipated soon. We’re still waiting to hear on a second grant proposal.

Thresholds for TPB and Leafminers in Apples

If you have a good market for #1 fruit (like pick-your-own blocks), then the threshold for tarnished plant bug in apples is a cumulative catch of 5 TPB’s caught per trap from silver tip to tight cluster stage. If  tight cluster stage comes and you still have not reached the threshold, look at the traps again at pink stage. A cumulative average of 8 or more per trap by pink would warrant control. For apple growers who aim to produce extra fancy apples, the thresholds are a cumulative catch of 3 per trap (ST to TC) and 5 per trap (ST to pink).

I’m happy that many apple growers don’t bother to spray for TPB any longer. Once bloom arrives, there’s no point to spray for TPB.

Leafminers: The red rectangle traps are very effective to predict whether or not you need an insecticide this year for these pests. Please remember they tell IF you need to treat. You’ve got a wide window for timing sprays if they are needed. The threshold varies with apple variety, because apples vary in their likelihood to drop fruit just before harvest, in response to leafminer damage. For McIntosh, it is a cumulative catch of 4 or more moths from quarter inch through tight cluster stage. For other varieties, the threshold is 9 or more moths, because other varieties are much less sensitive to leafminer damage. Now back to my point about when to treat. Some insecticides would be aimed at the eggs or very young larvae. They’d go on at pink stage. Examples: Esteem, Intrepid, Aza-direct, Assail. Others would be applied a while after petal fall, when sap-feeding stage of miners are visible. Examples: Altacor, Belt, Calypso, Lannate, Leverage, Proclaim…

There is another monitoring option. You could wait and count the sap-feeding mines shortly after petal fall. This is a trickier monitoring method than using the sticky red rectangle traps. Starting about 5 days after petal fall (try again 5 days later if find no mines) you examine the UNDERSIDES of CLUSTER leaves. You look for a slightly silvery patch on the leaf undersides. That’s where the tiny caterpillars have separated the lower epidermis layer from the internal spongy layer of the leaf. If you find 13 or more mines out of 100 leaves, it is worthwhile to treat for leafminers. I’ll show my sap-feeding mine photo now, but it should be a while before they appear.

 Green Pug Moth in Apples: Maybe a Bad Surprise?

The caterpillars of green pug moth are tiny yellow-green loopers that start feeding on expanding tissue soon after the buds open. The older ones often have a red-brown stripe down their backs. Normally a little foliage feeding would not be too bad. But as soon as the flowers open, the caterpillars feed on their most preferred tissues: the pistils of the flower buds. Chomping down the pistil results in no fruit from that bud. Sometimes the caterpillars are in very high numbers, and in other blocks (or years) they are in very low numbers, and do no significant injury. No one has determined how many caterpillars it takes to warrant a spray, but we do know a simple way to check: at pink stage, firmly tap the branches with flower buds over a white inverted frisbee or pie plate. Check a number of spots and see if you find what you think are significant numbers. If you find enough to worry you, apply an insecticide right away… before bloom. A few New Hampshire growers have had bad surprises in recent years. My photos show the technique (above) and the tiny caterpillar (below).

Rosy Apple Aphid Can Harm Cortland Fruit

If you have a lot of Cortland apples, it is worthwhile to check those trees at pink stage, to see if you have many colonies of rosy apple aphid. As the aphids feed on leaves, the leaves begin to curl up. Quickly they curl so tightly that they protect the colony from pesticides. As the insects keep feeding & growing, they produce a toxin that stunts the growth of the apple(s) adjacent to that spur. Affected fruit are puckered, and often are not marketable. The vast majority of varieties are not susceptible to the damage. Why check at pink stage? That’s the last opportunity to hit them with an insecticide, before leaf curling proceeds too far. Rosy aphids can appear yellowish, but older ones are pinkish or purple with a powdery exterior. The photo that shows one just starting to turn powdery was taken in early May, while the red ones were photographed in July. When you check, search for curled leaves. THRESHOLD??

Pink Stage is an Important Time for Apple Rust Diseases

Rusts are fungi that have two different species as hosts, and keep switching from one to the other. Galls or lesions on host 1 produce spores that infect species 2, and simultaneously, spores from species 2 infect species 1. We have several types of rust that affect apples. If you have problem with them, and have not been able to eliminate the nearby sources of spores, remember that the pink stage is usually when a significant number of infections occur. Cedar-apple rust usually hits apple foliage, while quince rust can affect the fruit. Japanese rust primarily hits apple foliage. Red cedar and some other junipers are key hosts. Even a tiny red cedar tree can produce enough spores to create problems. During rainy periods in the spring, the galls swell, and orange, fleshy telial horns appear. They are the source of the infective spores. I’ve got photos from previous years here. The round gall was on red cedar and is from cedar-apple rust. The other photo shows branches of common juniper, with slightly swollen spots from which long telial arms have appeared. They are from quince rust. The spores get released during rainy periods. My neighbor thought they looked like orange Christmas tree ornaments.

 Mummyberry

Blueberry growers take note: the fungal stipes of mummyberry fungus should be releasing ascospores now during rainy periods. The spores infect tiny opening blueberry leaves, where the fungus grows and produces conidia. The conidia are splash-spread spores, and they infect the fruit, while it is still green. At first, infected fruit are symptomless, but when ripening time arrives, they turn tan and shrivel up. Some of our varieties that are especially susceptible to the disease are Bluecrop, Blueray, Earliblue, Jersey and Berkeley.

Pollination Time for Apples, Blueberries

Many commercial orchards in New Hampshire bring in honeybee hives for pollination. To get the most out of them, here are some points. Honey bees require fairly warm temperatures (60F or higher) for foraging. If there is much of a breeze, foragers huddle close to the ground, or in other sheltered spots. If the wind picks up, honey bee foraging stops. Rain stops honeybee foraging, too. Apple blossoms have a relatively high sugar concentration in their nectar, so they are readily pollinated. Pear nectar has much less sugar, so it is really difficult to attract honey bees to pollinate them, especially when there are other choices, like dandelions in the orchard floor.

Put hives in groups across the orchard, rather than set them all at one end. Place hives on pallets or boards, rather than directly on the ground. This reduces the chances of cool water soaking into the bottom, cooling & slowing down activity. Try to put them in sheltered spots, out of the wind. If you can, place them facing southeast or east, so the morning sun warms it up early in the day.

It has been pretty dry this spring. If there is no clean water within a hundred yards of the hives, consider placing shallow trays of water nearby, with rough pine boards in them (drinking bees can grip well & not fall in).

We are lucky. In many New Hampshire orchards there are lots of native bees, and they pollinate the crop well by themselves (no need to introduce honey bees). We have over 120 species of them in NH. Most live singly, not in nests with hundreds of companions. A few (bumble bees for example) live in nests with a few—perhaps as many as a couple dozen — in a colony. Many of our natives fly in relatively cool, even wet weather. If you have active bees that are not honey-colored, they may very well be natives. Please remember that significant pollination from native bees requires nesting habitat in or close to the orchard. So it pays to protect that habitat. Some bees nest in tunnels in stems, stumps and twigs. Many bumble bees nest in old chipmunk, mouse or vole nests. About 70% of our native bees nest in the ground. Most of them prefer bare, undisturbed soil to dig their nest tunnels.

 

Alan T. Eaton
Extension Specialist
Integrated Pest Management

The University of New Hampshire Cooperative Extension is a public institution with a longstanding commitment to equal opportunity for all. It is the policy of UNHCE to abide by all United States and New Hampshire state laws and University System of New Hampshire and University of New Hampshire policies applicable to discrimination and harassment. It does not discriminate on the basis of race, color, religion, sex, national origin, age, veteran’s status, gender identity or expression, sexual orientation, marital status, or disability in admission or access to, or treatment or employment in, its programs, services, or activities.

April 14, 2016 Volume XII No. 1

Brown Marmorated Stinkbug: Risk of Agriculture Damage is Coming Closer

Crop damage from Brown Marmorated Stinkbug (BMSB) is getting closer to us, so we may soon begin to experience it ourselves. In 2013 & 14, it was reported in the lower Hudson River Valley of New York. My colleague Mary Concklin (University of Connecticut Cooperative Extension) reported that there was BMSB damage in Connecticut orchards in 2015, especially at one site where a number of apple bins had been transported from the lower Hudson River Valley (probably carrying some BMSB’s). BMSB’s have relatively long mouthparts, about ¼ inch for adults. The insects insert their mouthparts deeply into the flesh of the fruit, then inject saliva into the fruit. The saliva partially digests the flesh, and the insect sucks up the liquid. That means that most of the damage is below the surface, and often the only hint it is there is a slight depression and a minute hole, visible through a microscope. Damage to apples can look like boron or calcium deficiency. In sweet corn, damaged ears look OK until they are cooked, when the affected kernels turn brown.

Here in NH, we have been trapping for BMSB since 2011, using the very best trap & lure combinations available. We finally caught our first BMSB’s in a trap in 2014. Actually we caught two in that trap, which was in Milford. In 2015, we caught 45 adults and 27 nymphs in traps. Traps that did catch some BMSB’s were in Hollis, Brookline, Milford, Litchfield, and Nashua. Most traps in our (multi-county) network caught no BMSB’s, as has been the usual case.

We will keep monitoring. I anticipate that the first crop damage might appear in Hillsborough or Rockingham County. August/September seems to be the time they move into orchards, corn or pepper fields, beginning at the wooded borders. If I had money to bet, I’d anticipate the first NH crop damage would be in 2018, possibly later. By the way… adults are emerging from inside the walls of buildings, and will continue to do so through May, possibly later. So, you could see live adults now, especially in a building.

Exotic BMSB Parasite

Trissolcus japonicus is one of the BMSB bio-control agents that is being studied in the USDA quarantine labs in Beltsville, MD. It is a tiny wasp that searches for BMSB eggs, and attacks them. Is it safe to release in the USDA? Officials haven’t finished examining that question. But the answer might be moot. In 2015 we learned that the species was discovered outdoors in Maryland and Oregon/Washington. My reaction was that it must have escaped from the quarantine facility. No. Researchers analyzed the DNA of specimens from these new sites, and found it did not match the strain being studied in quarantine. They are the same species, but not the same strain. I’m waiting to hear if they will go ahead and allow release of the agent, or if they will finish their testing. One question they ask is whether the parasite will attack eggs of other species, besides BMSB. We would not want to introduce something that might, for example, parasitize eggs of predaceous stinkbugs.

Controlling Mexican Bean Beetles with Metalized Mulches

A poster at the January Northeast Plant, Pest and Soils Conference showed a study of light-reflecting mulches tested for Mexican bean beetle control in snap beans. Such mulches have been tested before. As a college student at the University of Massachusetts I helped with a study of reflective mulches in repelling aphids from squash. They worked. Amy Ouellette studied the yields of tomato with reflective mulch. Now this study from Virginia shows that metalized mulches reduced Mexican bean beetle damage and increased yields, compared to bare soil plots. Of course, these were plots that had significant numbers of bean beetles. If you have problems with MBB in your garden, and don’t wish to use an insecticide, this might be an option to test. Two problems: 1) you’d have to let the soil warm up well before applying the mulch. 2) Some of these reflect sunlight so strongly, you feel like wearing sunglasses to pick the crop. No, that’s not a joke.

New Insecticide for Piercing-sucking Insects that Spread Diseases

Recently my colleagues and I discussed how serious aphids are on brassica crops and spinach. Then, I learned about a new insecticide at the Northeastern Plant Pest and Soil Conference. Flupyradifurone is a new insecticide called Sivanto, from Bayer. It is in a new chemical family, shows translaminar and systemic activity. The manufacturer seems to be targeting it for insects with piercing-sucking mouthparts that spread diseases. Aphids, leafhoppers and a few other pests are on the label. Brassicas, spinach, potato, grape, pome fruit and other crops are on the label. I don’t see bee warnings, but I do see cautions about runoff & water contamination. The CDMS database has the label, which is dated March 2015. That must explain why we don’t have it in the 2014-15 Veggie guide.

Legality of Sulfoxaflor Use

On November 12, 2015, EPA cancelled the registrations of (relatively new) Dow insecticides containing sulfoxaflor (Sequoia, Closer and others). This unusual action occurred as a result of a lawsuit that alleged EPA did not have enough data to have registered these products, when it did a year or more ago. When many of you were harvesting apples, the ninth circuit court of appeals issued their ruling to the EPA (Sept 10, 2015), which forced EPA into its action. My immediate reaction to the November announcement was to ask what would happen to the pesticide that was already sold, and in the hands of growers and orchardists.

The answer is that EPA will allow continued use of such material already in growers’ hands, provided they follow the label. Closer is the product most likely to be familiar to fruit and vegetable growers. A fairly specialized insecticide, it controls aphids, whiteflies, some scales and psyllas. So, you can keep on using it.

Fruit Bud Stages

In Durham and Madbury, McIntosh apple buds were in green tip stage on Monday April 4^th. I examined them while standing in a fresh 2” of snow. Blueberry fruit buds have swollen buds, and some varieties have progressed to the loose bud scales stage. Raspberries have about ¼ inch of growth, and thornless blackberries show no movement. Peach flower buds appear dead. It is possible that the low temperatures we had April 3^rd & 4^th may have damaged some apple buds. On Monday April 11^th, the apple buds look virtually the same, but the covers have been removed from the thornless blackberries, revealing about ¼ inch of growth from the buds.

Apple Scab Ascospore Maturation Model

The apple scab ascospore maturation model begins when 50% of the fruit buds on McIntosh are between silver tip and green tip stage. In Durham and Madbury, probably that was Friday April first.

Fireblight

If you had fireblight in your apple orchard last year, consider making a copper spray at silver tip and/or green tip stage. That can kill most fireblight bacteria exposed on the surface, and reduce the chances of more strikes this year. The formulation does not matter. What is important is to apply 1 to 2 lbs of the metallic equivalent per acre. Applying copper past the ¼ inch green stage increases the risk of phytotoxicity. For some of you, it is too late, but we had fireblight strikes reported pretty far north last year, so there may still be time in some spots.

Monitoring Tree Fruit Insects with Traps

If you monitor tarnished plant bug activity in your apple orchard, the time to hang traps is silver tip stage. If you hang them late, it will be hard to use the threshold, which is designed to measure the number of TPB’s starting at silver tip stage. TPB traps are hung at KNEE height, toward the tips of a branch, preferably over a grassy part of the orchard floor. The red sticky rectangular leafminer traps go up at about ¼ inch green stage. They go on the south or southeast side of the trunk, at knee height. Warm, sunny weather will hasten activity of both those insects. Later this week the forecast shows sunshine and milder temperatures… not really warm, though.

Mummyberry

Blueberry growers take note: the fungal stipes of mummyberry fungus should be emerging from last year’s mummified berries on the ground. The growth starts as a dark brown spike, then enlarges at the tip to form a mushroom, and lightens in color. In my one of my photos, there are two fungal stalks (stipes), one of which has already has a tiny opening at the tip. In the other, the “mushroom cup” has formed well. They begin releasing spores when the mushrooms are partially open. This usually coincides with the first green blueberry tissue being exposed. Urea sprays are designed to burn off those fungi, and applying a layer of mulch is designed to bury them. For most sites in southern NH, it is a bit late to consider burial by mulch now.

2016 Tree Fruit Management Guide Updates to the 2015 Guide 

The New England Tree Fruit Management Guide is a publication produced in collaboration by the Cooperative Extension systems of the Universities of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont.

The  most recent printed edition is the 2015 edition. This is available for purchase from UNH Extension (603-862-3200). As of the writing of this newsletter, UNH Extension and Alan Eaton have 7 remaining guides. They are also available from the UMass Bookstore. The cost is $36.

In 2016, instead of printing a new guide, the authors decided to produce a short addendum with know updates and changes where current information differs from the 2015 edition. The 2016 Update to the Tree Fruit Guide is available HERE. 

Alan T. Eaton
Extension Specialist
Integrated Pest Management

The University of New Hampshire Cooperative Extension is a public institution with a longstanding commitment to equal opportunity for all. It is the policy of UNHCE to abide by all United States and New Hampshire state laws and University System of New Hampshire and University of New Hampshire policies applicable to discrimination and harassment. It does not discriminate on the basis of race, color, religion, sex, national origin, age, veteran’s status, gender identity or expression, sexual orientation, marital status, or disability in admission or access to, or treatment or employment in, its programs, services, or activities.

October 28, 2015 Volume XI No. 8

Orchard Vole Management and Rodenticides

Fall is traditionally the time that New Hampshire orchardists consider rodenticide application to control meadow voles (and, to a degree, pine vole). If you plan to do this, please read my vole management publication, especially the rodenticide section.

If you use one of the anticoagulants, I strongly recommend that you use some type of bait station. That maximizes the likelihood that the target organisms (usually meadow vole or pine vole) will be killed, rather than many other things. We have two types registered in New Hampshire, Diphacinone (Ramik Brown) and Chlorophacinone (Rozol). The Ramik label specifically states the stuff is applied after harvest is complete (including drops), before spring growth, and when 3 days of rai/snow free weather are expected.

Brodifacoum is a second-generation anticoagulant available to people with restricted use permits (for use in and around buildings… not in the orchard), but I STRONGLY ADVISE AGAINST USING PRODUCTS WITH THIS TOXICANT. I think it poses too great a wildlife risk to be used.

Zinc phosphide is the toxicant most commonly used in NH orchards, and it has almost zero risk of secondary poisoning, because it kills quickly and the material breaks down quickly. But it has a high risk of PRIMARY poisoning…killing an organism that directly eats the bait. So if you plan on using ZnP, minimize the risk of killing non-target organisms by avoiding corn as the bait (birds and others readily spot it and eat it), and avoid broadcasting it on bare spots.

PAD Assessment Reminder

PAD is an acronym for potential ascospore dose, and it is a measurement that can be very important to us trying to manage apple scab. Many decisions about whether or not a fungicide is required are affected by how many bazillion spores threaten your trees. If your PAD is high, you may have to do more fungicide spraying than you’d like, to protect your fruit. If PAD is very low, you can eliminate some of those sprays.

Measuring PAD is an activity that is done in the fall, before many apple leaves have fallen. Instructions are on pages 66 and 67 (section 6.23 of the 2015 New England Apple Pest Management Guide. If you do not have a copy of the 2015 guide, the 2014 version is available on line). It is not difficult. If you have had scab problems, it may be wise to measure the PAD of your orchard.

Fall SJS Spray?

Two growers asked me about a fall insecticide for San Jose scale. I had never heard of that timing, but last week heard a presentation by Dave Combs from New York’s Hudson Valley Lab. He looked at that option. The data suggested to me that it might work at that time, but it did not seem to offer advantages over our standard options. I looked at pesticide labels for the products he tested. They do not appear to currently allow you to try it at that time.

Apple IPM For Beginners

My colleagues at Cornell Cooperative Extension produced a color guide (about 35 pages) called Apple IPM for Beginners – A guide for new apple growers to protect apple orchards from pests, in fact sheet format. You can view it online. If you have a color printer, you might wish to download the entire 3.2MB guide. I think they did an outstanding job, and I’ve learned some new things from it already. You can, too. BTW… it is free.

August 25, 2015 Volume XI No. 7

Apple Summer Diseases

 Apple Maggot

All varieties of apple are vulnerable to attack by apple maggot, but my fruit evaluations over the years have pointed to a pattern where some varieties get more damage than others. This could be in part because of preferences of the females laying the eggs. But it could also be affected by growers’ pattern of insecticide use… not using traps to discover when the flies are active, stopping spraying too soon, beginning too late. So, keeping those factors in mind, here’s my data from 1996 to 2005. In that period, I examined 119,500 apples. These are visual examinations. No fruit were sliced open to search for tunnels.

Variety                        incidence of AM blemishes

McIntosh                   18 of 50,740 fruit (0.035%)

Cortland                    33 of 29,000 fruit (0.114%)

Delicious                   27 of 12,430 fruit (0.217%)

Idared                        4 of 420 fruit        (0.952%)

Northern Spy            3 of 670 fruit        (0.448%)

Gingergold                1 of 320 fruit        (0.312%)

Gravenstein              1 of 340 fruit        (0.294%)

Empire                       7 of 5,040 fruit     (0.139%)

Macoun: 0 of 7,830 fruit. Paulared: 0 of 2,600 fruit. Gala: 0 of 2,650 fruit. Mutsu: 0 of 1,560 fruit. Honeycrisp: 0 of 1,010 fruit. Plus other varieties in small amounts…

The mix of varieties we grow has changed, and now I see more Gala, Mutsu, Honeycrisp, Fuji, Gingergold, Zestar, Akane and other varieties. But for what it’s worth, this is the pattern I’ve seen. Note that McIntosh, the variety that has the largest acreage here, has among the lowest apple maggot damage rates. Cortland has a damage incidence three times higher than McIntosh, and Delicious has an incidence 6 times higher.

White Apple Leafhoppers

We have two generations of white apple leafhoppers per year, and the adults of the second generation fly in September. The nymphs and adults both drop brown poop on whatever is below them, like your fruit, or the insect trap in the photo. When we get a light rain, heavily decorated fruit appear to be dripping in yellow droplets…not too appetizing. The leafhoppers feed on the foliage, creating white stippling. But many growers feel the most annoying problem is bothering pickers by flying in their faces. So some growers elect to apply an insecticide if leafhopper numbers get high. You can do that, but a better course of action (next year) is to monitor the first generation of leafhoppers (shortly after petal fall) and treat then if the population crosses the threshold.

Vegetable Insect & SWD Trapping Data

So far this year, sweet corn insect catches have been pretty low, but you can see the details yourself at the IPM Trapping & Monitoring page of our website.

Spotted Wing Drosophila

The catches Aug 1^st to 7^th were mostly 0-4 per trap, with a couple sites having 30. The week of Aug 2^nd to 9^th had a similar pattern, with catches up to 42 in a trap, especially in woods edge and in raspberries or plums. The week of Aug 9^th to 15^th had the same pattern with some catches as high as 60! But again, Most traps still have low numbers.

In Sullivan and Grafton counties, SWD catches are still very low, typically zero to 3 per trap per week. This is the same pattern we have seen since SWD arrived… the areas with cooler temperatures have slower buildup and lower numbers. Overall, New Hampshire catches so far seem lower than last year, but they should continue to build. You can view our trap catches on the IPM Trapping & Monitoring page of UNH Cooperative Extension’s website. When you reach the SWD data, click on the town that is of interest to you, and various weeks will appear under that town. Select the week of interest, then click on the “submit” button. The data will then be displayed for that site & week.

Wasp Control on PYO Farms

Stinging wasps can be a threat to both customers and farm workers. Late summer and early Fall seems to be the time of year when the threat is greatest. The wasp colonies are at their largest size then, and sometimes frost starts limiting food options for wasps. I suspect that might help switch them into a more aggressive pattern, but I really don’t know. I do know that it is better to deal with the problem relatively early, if you can. We have 11 pretty aggressive species in New Hampshire, including 9 species of yellow jackets, plus bald-faced hornet and giant European hornet. We also have species that are much less aggressive, like brown paper wasps. Frequently the less aggressive ones pose so low a risk, they can be left alone.

Please remember two things. 1) If you are allergic to bee/wasp stings, do not attempt to eliminate a nest yourself. Have someone else do it. 2) During the daytime, mark the position of a nest you want to eliminate. Then return at least 1 hour after dark, to treat it. Why at night? All of the workers should be back in the nest then.

Consider buying a can of wasp and hornet JET spray. Jet is not a brand… it means the stuff is designed to shoot a solid stream of product, often up to 10 feet or more. I would not bother to try the canned sprays that create a fine mist. .Approach the nest gently, quietly. Aim directly into the opening. This might mean positioning the spray can a bit below an aerial nest. I use a red light to help me see what is going on. After hitting the opening for several seconds, stop and walk away. Stay away until the next day. If you still see wasps flying in or out, re-treat the next night.

Large aerial nests are fairly easy to find by their size. Nests inside walls or in the ground are much harder to spot. To find them, I look for insects flying into or out of a hole. I do one additional thing when treating a ground nest. In addition to the flashlight and spray can, I bring along about a quart of damp sand. As soon as I have stopped spraying, I dump the sand over the entrance tunnel. That helps seal in the toxicant and prevent wasps from escaping.

One contributor to the problem may be a bit hard for you to control: wasps are attracted to dropped fruit and spilled sugary things (like cider). Removing drops is often impractical, but it works. Here is a link to my publication on controlling wasps.

Flyspeck and Sooty Blotch of Apple: As of August 17^th in Durham, we have accumulated 295 hours of leaf wetness since the end of the first 270 hour cycle. So that means the second cycle ended on August 12^th and spores started getting released. As of Tuesday morning Aug 18^th we are 25 hours into the 3^rd cycle of flyspeck. Remember to check the days to harvest if you apply a flyspeck fungicide. Manzate, Dithane, Polyram and Penncozeb have a 77days to harvest interval! Sovran has a 30 day interval, while others have 14, 1 or zero.

Alan T. Eaton

Extension Specialist

Integrated Pest Management

July 22, 2015 Volume XI No. 6

Apple Summer Diseases

Flyspeck and sooty blotch we refer to as “summer” diseases of apple. The number of hours of leaf wetness after petal fall (we abbreviate this HLWAPF) is a critical factor in growth of the fungi that cause the diseases. Each cycle of the fungus requires 270 HLWAPF to complete (200 hours if you are using modern leaf wetness equipment). At UNH, we were relying on equipment that has repeatedly failed at critical times this spring. So it wasn’t until July 8 that we discovered the first 270hr cycle had been completed (in Durham) on June 28^th. That means spores from the numerous alternate hosts (maple trees, raspberry and blackberry, etc) released spores starting then, and now we are in the second cycle, where those fungi are trying to grow on apples. As of July 20^th, we [in Durham] had accumulated 137 hours of wetness in this second cycle. Some sites have a history of summer disease problems, probably because they have lots of nearby hosts providing spores.

Brown Rot on Peaches

Peach fruit become really susceptible to brown rot as they mature and begin to ripen. If we have warm, wet weather, that helps still more. Anything you can do to reduce mechanical injury to the fruit will help reduce the problem, and refrigerating fruit will help too. The 2015 New England Tree Fruit Management Guide lists fungicide options. Note that they vary widely in days-to-harvest… from zero to 14 days!  Yesterday I saw some nectarines that were heavily attacked by the fungus.

Fire Blight

Driving home from a tree fruit meeting in Alexandria, Cheryl Smith noted severe fireblight damage on roadside apples in a churchyard in Alexandria. Scattered strikes have been seen as far north as Lisbon this year.

Apple Maggot

Some orchards have trapped several apple maggots by now, and others still have none. That is normal. There is great variability in the population (and timing) from site to site. Right now, I would expect early varieties (Gravenstein, Early Bird, Lodi, Vista Bella) to be most at risk.

When you reach a cumulative average of 1 apple maggot fly per trap, it is time to apply an insecticide. If you use odor-baited traps, the threshold is an average of 5 to 10 per trap. (the big spread in range is one reason I don’t add odor lures for this species). Then, for the next 7-12 days, discount any AMF’s you happen to catch. If I’m using Sevin, I do this for 7 days, since the residue is shorter lived than that from the pyrethroid insecticides, or Guthion, Imidan. If I’m using the labeled rate of a pyrethroid insecticide (Warrior, for example), I discount for 12 to 14 days, since those insecticides have long residual action. When it is time to start harvesting a block, I move the traps to later-maturing trees. At the end of the season, I remove the traps, put them in heavy plastic bags (keeps dirt & dust out) and store them until next July.

Spotted Wing Drosophila

One point to remember regards a key alternate host: pokeweed. The fruit are excellent habitat for SWD larvae. If you grow fruit that are vulnerable to SWD, it is important to destroy pokeweed before it produces fruit. I’ve included a photo as a reminder.

We caught our first SWD on June 23^rd, a bit of a surprise that early. One was tapped in Essex Co, MA at about the same time. Finally we trapped another fly on July 8^th, then at another site the next day. These numbers are really low, but should rise. In your plantings, I recommend considering an insecticide application if both 1) your crop is ripe and 2) you have trapped one or more SWD’s on your farm this year.

Details on traps, baits, how to hang, etc are on the SWD page.  The 2015 pesticide options are there as well, thanks to Mary Concklin of University of Connecticut Cooperative Extension. If you click on the trapping data link on our SWD page, you can view our trapping results, though with a slight delay. If you monitor traps yourself, you won’t have that delay.

There’s Still Time Left: Tree Fruit Leaf Tissue Testing for Nutrient Analysis

For tree fruit, leaf sampling for nutrient analysis should be done in late July through early August. The forms have the specific instructions, which can be found on the Problem Diagnosis and Testing page of UNHCE’s website.  Look near the bottom of the page, under “Additional Testing Services”. You can also download the form here.

Vegetable Insect & SWD Trapping Data

Those sweet corn growers who looked at the trapping data for the week of July 6-11 saw that we detected low numbers of corn earworms then. That is a bit earlier than we expect this pest, and is another example of the value of monitoring with traps. Sometimes you detect surprises! Numbers were not very high, but any sweet corn in fresh silk at that time was vulnerable to attack. Because of a delay getting help here on campus, we had just started setting sweet corn traps in the seacoast… but caught three earworms in the one trap we had set, in Derry. It may be that this flight was heavier along the coast, as compared to inland.

If you grow sweet corn, chrysanthemums, peppers, squash or pumpkins, and want to see the current year’s trapping data for corn borers or other insects, point your browser to our IPM Trapping and Monitoring page. Once on that page, you’ll see that one of the options is to view the current data, and it will show you how many insects were captured in traps at various sites. You could look at several weeks of data, if you wish. To help protect privacy, we don’t include farm names on the site, just the town names. On the vegetable insect trapping data pages, you’ll see that on the far right side it says “No Spray Recommended” after each entry. That’s because we want to keep the spray recommendations private as well. Look at the very bottom of the page as well. There you’ll see the threshold information, to help you decide what to do when a particular number of earworms or other insects are caught. The data is ready for you to examine any time you wish, for sweet corn & squash trapping. As I finalize this on July 21^st, we have caught a few fall armyworms… not too many yet.

Summer Caterpillars

On apples, we see two large caterpillars regularly, in summer. Both can completely strip leaves off a limb or two, or even the whole tree. Both are highly recognizable. Cecropia moth is one of our native silkworms, and the larvae are light green with a series of colored spiny knobs. They can get HUGE.

The second species is called redhumped caterpillar, and you can see why from the photo. This species is gregarious; you almost never have just one. The female lays eggs in masses, while cecropia moths lay their eggs singly.

In blueberries, we often see two very closely related species, yellow-necked caterpillar and its look-alike, Drexel’s datana. Like red-humped caterpillar, they are gregarious species, and a bush might get largely stripped of leaves if you don’t keep checking.

All of these species can be controlled (if that’s necessary) by either chemicals or Bacillus thuringiensis sprays. Since most of our blueberries are sold on a pick-your-own basis, and the caterpillars occur during picking season, many blueberry growers avoid using the chemical sprays. Some growers spray nothing, and when customers mention finding the caterpillars, the grower points to it as proof that he/she doesn’t spray.

Fruit-Related Events:

There are many events that might be of interest on our events calendar. Among them are:

Tuesday, July 28, 2015. Sprayer Calibration & Vegetable Twilight Meeting, Moulton Farm, Quarry Rd, Meredith. The sprayer calibration workshop is 3 to 4:30PM; Veg meeting will be 5:00 to 7PM

Alan T. Eaton
Extension Specialist
Integrated Pest Management