Tag Archives: tarnished plant bug

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 3rd 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 15th. 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 9th 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.

 

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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 4th. 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 3rd & 4th may have damaged some apple buds. On Monday April 11th, 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

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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.

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2016 Tree Fruit Management Guide Updates to the 2015 Guide 

TFGuide

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.

April 28, 2015 – Vol. XI No. 3

Bud Stages

On Monday April 20, almost 50% of the McIntosh apple buds in Durham/Lee were at silver tip and 50% were at early green tip. Peach buds were almost all dead. Blueberries were all swelling. Raspberries showed about ¼ to ½ inch of growth. On Wednesday 22nd, McIntosh buds in Derry & Londonderry were mostly at ¼ inch green stage. There were lots of peach buds swelling.

On Monday April 27th, 95% of McIntosh apple fruit buds in Durham/Lee were at the half-inch green stage.  There were many more live peach buds than I thought earlier.  Blueberry buds were swollen (tight scales), and raspberries showed ½ to 1 inch of growth from the buds.

Setting up Traps for TPB & Leafminers in Apples

If you monitor tarnished plant bugs in your apples with white sticky rectangle traps, the time to hang them up is at silver tip stage. If you have passed that stage, it is too late to get an accurate assessment of TPB numbers. The traps are mimics of a cluster of opening foliage (works on the TPB’s anyway), so they should be hung towards a branch tip. Also important: hang them at knee height, over a grassy (not bare) part of the orchard floor. IMG_1769

Are you monitoring leafminers? The red sticky rectangle traps for those go up at ¼ inch green stage. They get stapled to the south or southeast side of the trunk, at knee height. As with TPB traps, you check them every week and write down the numbers caught. I’ve had growers ask me if they could stretch out the interval, and check after 10 to 14 days. I don’t recommend that, because the trapped insects gradually turn black, and get very difficult to identify if they’ve been caught a long time.

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Recognizing the catch is relatively easy for both. Leafminer moths are narrow, about 3mm long (slightly over 1/16 inch). Their wings are bright silvery white, with dark markings. Overwintered tarnished plant bugs are dark, almost black, and shield-shaped. They are 4 to 5mm long (almost ¼ inch), with long, thin antennae.

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Threshold for TPB’s in Apples

If you have a good market for #1 fruit (like PYO blocks), a cumulative catch of 5 TPB’s caught per trap from silver tip to tight cluster makes it worthwhile to spray. If you haven’t reached threshold by tight cluster stage, wait and look 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). Many apple growers don’t bother to spray for TPB any longer. I think that’s great!!

Threshold for Leafminers on Apple

The traps are very effective to predict whether or not you need an insecticide this year for these pests. Threshold varies with apple variety. 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.

Insecticide Options for Leafminers on Apples

Once you have determined that you do need to control leafminers this year, There is a really wide range of insecticide options & times.

1) Insect growth regulators (Esteem and Intrepid for example) are most effective on eggs and very young larvae, so if you need to spray, and wanted to use them, spray at late tight cluster (pre-pink) or pink stage. Organic growers don’t usually have leafminer problems, but if they do, Aza-direct is OMRI listed, and would be used then.

2) Vydate is an organophosphate insecticide, rough on beneficials, but effective on leafminers. The preferred timing for that would be at pink, because spraying Vydate soon after pink can cause erratic fruit thinning.

3) Materials that are effective on the young larvae (sap-feeders) come next. That should be soon after petal fall. Proclaim is one example. You use it with a surfactant, and it has some translaminar (foliage penetrating) action. Exirel is a new one that would be used at that time. Gladiator and Tourismo are both relatively new combination products that would be used then. The Voliam flexi and Actara labels have similar language — apply right after petal fall. Other labels say just during the sap-feeding stage, so that could be a little bit later (watch for signs on your leaves). Agri-Mek, Altacor, Assail, Belt, Calypso, Delegate, Lannate, Leverage, Provado, Entrust and SpinTor are in this category. Some Insecticides require a surfactant or horticultural oil be added to the tank, to penetrate properly and be effective. Be sure to check the labels!! Agri-Mek, Delegate, Agri-Flex and SpinTor are in this group that need to be tank mixed with a surfactant or oil.

4)  We have a number of pyrethroid insecticides that also work on leafminers. I believe they affect adults (or eggs, if you have high enough gallonage to hit them), not the immatures, which are inside the leaf layers. Pyrethroids (in general) are quite persistent and broad spectrum, so they can be very harmful to beneficial insects. I downplay them as an option for leafminers. Examples include Asana, Baythroid, Delegate, Warrior.

Label language: Avaunt is registered to suppress leafminers, which to me means it doesn’t work too well. Watch out for this phrase. Repeat sprays: If you apply an insecticide for this generation of leafminers, you should need only one treatment. If you treat (correctly) for the first generation, it would be rare to require a leafminer treatment later in the season. Later in the season, if you do find out that you need to treat for leafminers, generally it would take two applications to provide control, while controlling this first generation would require only one.

Apple Scab Update — Cheryl Smith

SARE project collaborators are still monitoring ascospore maturity in New England. Massachusetts people are doing petri dish and squash mounts (a graduate student project). In New Hampshire and Maine, spore trapping is going on [MacHardy, Smith, Schneider]. We will know the actual start and true end of the ascospore season. In Durham on April 20th, 45% of the McIntosh buds were at green tip stage. By April 22nd, it was probably over 80%.

There is now a NEWA weather station in Hollis. The model says there was an infection period Monday-Tuesday. It was wet long enough, though cool. Only 3% of the ascospores were mature, but we don’t know how many (if any) got released. In Durham, there were none trapped. The Durham weather station showed 39 Apple scab ascospore degree days accumulated since 4/15, but the 15th was before our biofix. Soooooo, very southern NH may have had an infection period. The scab model on the NEWA website (for Hollis NH) estimated 3% of the ascospores were mature, and we had an infection period then. It predicts 15 days (after the Mon-Tues wetting period) for any symptoms to show up. If you have blocks of apples that you are SURE have very low inoculum (urea spray, leaf-chopping, or passed a PAD count in the Fall) you don’t need to worry about a few percent of spores being mature (prob. below 8-10%). But, if you’re not sure, it would be wise to be covered before the next significant rainfall (the next infection period). If you are beyond green tip stage and are not covered, it may be good to apply a kickback fungicide. Check Alan’s Fruit pest update telephone (862-3763). I or Bill MacHardy or Deb Schneider will be giving spore maturity info.

Cedar-Apple Rust — Cheryl Smith

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We had lots of cedar-apple rust [CAR] in 2014, with great jelly horns visible. So far, no horns are visible on galls, but they will begin releasing spores soon (during rainy periods), through May. Leaf spots should be visible by June. Some varieties are really susceptible, such as Braeburn, Fugi, Gala, Ginger Gold, Golden Delicious, Idared, Mutsu, Rome, and others. Remember that the best management practices for CAR are to grow resistant varieties, and separate apples from the alternate hosts, redcedar.

Oil for Red Mite Eggs

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The easiest time to smother mite eggs with oil is when they are respiring the most rapidly. That occurs just before they hatch, so the ideal time on apple is during the tight cluster stage. In the past I’ve shown tentative sampling procedures and thresholds for ERM eggs in early spring. But I’ve found no one that used them. I’ll offer some added, easy guidance: If you have a block where your pruning gloves got orange streaks after handling the branches, that’s a block to be sure you treat with oil. Some growers have so much acreage to cover, that they have to begin before TC stage. You want to get this treatment done before pink stage, because that’s when the eggs start hatching, and the motile mites can just walk out of the oil.

Be careful about temperatures, when applying oil on apples. Try to apply it when the temperature won’t dip down into the 30’s within 24 hours of application. Also, don’t mix it with Captan, and don’t use Captan as the next fungicide after applying oil. Getting Captan and oil too close (or mixing them) results in brown phytotoxic spots on the foliage.

Winter Moth Update

There is very little risk of winter moth injury here in NH, except in southeast Rockingham County. But we do have another species that is very closely related, with nearly identical biology, which hybridizes with winter moth. So you might experience problems from a very early season, green looper that chews holes in foliage. Damage is worst on oaks, maples, blueberries and sometimes apple, especially bordering woods. The moths lay eggs in late fall and early winter, in bark crevices of trees. Winter moth eggs hatch very early, as buds are swelling and beginning to open. One odd quirk: the (orange) eggs turn blue just before they hatch!  When we see problems, it is usually due to a gradual buildup, rather than sudden appearance of a problem. Yes, chemical insecticides work on the caterpillars, but so do biological insecticides like those based on the caterpillar strains of Bacillus thuringiensis. Trade names include Dipel, Biobit, Deliver, Javelin. Timing? Often that’s pre-bloom.

Stem Galls on Blueberry

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I received these galls just after the last newsletter was issued. They were created last year, by a wasp named Hemadas nubilipennis Ashmead. No, there is no common name, but you could call it blueberry stem gall wasp, and entomologists and blueberry growers would both understand you. I see these mostly on wild and backyard blueberry bushes. The adults are tiny black wasps, and they fly in June or early July. If you see old galls in mid-summer, with tiny holes in them, the wasps have already emerged. If there are really high numbers of galls on a bush, they can reduce fruit production. That is rare, by the way.

In my backyard, I prune these out during the dormant season, and burn them. If you see low or moderate numbers of them, I wouldn’t worry. The species is heavily parasitized by other wasps, and that may be one reason that I rarely see high numbers of these galls.

Girdled Grapes

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I pruned my grape vines before the snow had fully melted. A week later the rest of the snow melted, and revealed that both vines had been girdled by voles over the winter. I asked George Hamilton if some latent buds might break below the girdle point, and save the vines. He said that might happen, so I’ll wait and see. In the meantime, there is a lesson. Meadow voles are the most common cause of this girdling, and two things made it more likely for this problem to occur. One was that I did not keep the weeds down under these vines. The other is that the previous owner had piled small rocks (4″ to 9” in diameter) under the vines and bordering the entire garden. I guess this was to create a visual border. Meadow voles really like both situations, because they get protected from most of their enemies by thick grass or weeds, and rock piles. When the snow fully melted, I found a vole nest only 3 feet from one girdled grape vine, and another nest 5 feet away. I suppose I could have installed vole (“mouse”) guards of ¼ inch mesh hardware cloth around each vine. But George sent me photos of one vineyard where the girdling was very high on the plant. It would have been difficult to construct guards to prevent that. My future efforts will be on removing the rock piles, and keeping weeds controlled or mowed.

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Brown Rot on Stone Fruit — Cheryl & Alan

Brown rot hits our stone fruit, and is most favored by rain and cooler temperatures during bloom. Removing mummies from the trees will help in managing this fungal disease. Insect control can help, too, by eliminating insect injury on the fruit as a point of entry for the fungus.

Alan T. Eaton
Extension Specialist
Integrated Pest Management

April 1, 2014 — Volume X No. 1

How did Fruit Pests, Parasites Predators Survive This Cold Winter?

The answer varies, according to where and how each species overwinters, and its tolerance for cold. Some insects and mites overwinter on the twigs, so they are fully exposed to the prolonged cold temperatures, and also to the brief extremes, like a couple of hours at minus 12F one morning. European red mite eggs and apple aphid eggs have almost no protection, so I’m expecting lower than usual survival rate for them. Egg masses of eastern tent caterpillar are also exposed on twigs, but they have a protective covering. They might do a little better.

Our predaceous mite Typhlodromus pyri overwinters under scales of bark on the trunk, close to the ground level. That’s where the temperatures are coldest. Some may have gotten protection from deep snow, but overall I’m anticipating that they will not survive well, and may take time to recover this summer.

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Tentiform leafminers (and their parasites), trumpet leafminers, and apple scab fungus overwinter in last year’s dead leaves. Since they have been covered by an insulating layer of snow most of the winter, they should have been pretty well protected from the extremes, and I expect them to survive at close to their usual rates. I think tarnished plant bug falls in this category too.

Some are really well protected, and I anticipate normal survival. Plum curculio is in this category. It burrows under the leaf litter in woods. Apple maggot and blueberry fruit fly survive as pupae in the soil, so they are very well protected.

Unknown: we still do not understand just where spotted wing drosophila overwinter. We think they do so as adults, and probably in woodland, but no one knows yet. I cannot guess how well they will do. With such a high reproductive rate, and time for 10 or more generations per year in southern NH, I think SWD could recover quickly if overwinter survival was poor. So it might be possible that we would see lower than usual numbers in July, if overwinter survival was poor. But it could recover by August.

New Hampshire SWD Crop Losses

In December and January, Becky Sideman, George Hamilton and I set up another online damage survey for SWD. We did the first such survey in December 2012, and learned from that that NH crop losses were $1.516 million that year. Wow! This time, we made some slight modifications in the survey tool, but overall sought the same information. The survey was open for about 7 weeks, and then we crunched the numbers. We learned that 2013 NH SWD crop losses were down by almost two thirds. The total loss figure was $526,000. The SWD catch was pretty comparable between the two years, with the catch beginning and peaking about 1 week later in 2013, compared to 2012.

There are plenty of people to thank for helping achieve this $987,000 drop in damage. On the survey, several growers thanked UNH Cooperative Extension, and it was gratifying to read the results. We really did work hard to help you. But we also benefitted from significant collaborations with extension and research colleagues in other states, and grant funding from USDA-NIFA and the NH Department of Agriculture, Markets and Food. And of course, the people who listened, read, and changed their behavior to successfully control this pest were… you, the growers. You can read more details on the losses at the SWD page of UNH Cooperative Extension’s website.

Deer are Hungry Now

Deer are really hungry now, and as the deep crusty snow melts, they gain access to more feeding sites. Be sure those fences are up and gates are closed, especially at night. After I pruned my two apple trees, I picked up all of the prunings and carried them far away from the trees. Early the next morning, I saw that the prunings had been heavily hit by deer.

San Jose Scale

Were you one of the growers with San Jose scale on apples at harvest time? If so, you might consider a change or two to this year’s management plan for the affected block(s). One is to be sure that affected trees are pretty well pruned. We often see SJS gain a foothold in trees that get poor spray coverage, and canopy density is a factor. Another is to consider a spray to affected trees at the half-inch green stage. Options include superior oil, Lorsban, Supracide, Esteem plus oil, or Centaur. Excellent coverage is required to get good control. To me, a better timing of a SJS spray is when the crawlers have emerged. That will occur in June. You can optimize the timing by installing a maximum/minimum thermometer in the affected block, and checking it daily, starting at bloom. You’ll be figuring out degree days. I’ll have more details later. Do you use solid tree guards, like the wrap-around plastic strips? If so, consider replacing them with something that allows sprays to penetrate and reach the trunk. The worst SJS infestation I ever saw was on several young trees with wrap-around spiral “mouse” guards. When we unwrapped the guards, there were hundreds (possibly thousands) of scales living on the bark underneath, where the insecticides could not reach. In this case, all that was needed to correct the problem was to remove the guards. Normal spraying did the rest.

Pruning and Pest Management

Pruning can help lessen pest problems, in several ways. One obvious one is to reduce the density of the tree or bush canopy. Very dense canopies are difficult for sprays to penetrate, so we can see an increase of problems from San Jose scale, oystershell scale and other pests in poorly pruned crops. Adults of spotted wing drosophila really like dense canopies. Dense canopy also lengthens foliage drying time. Apple scab, black rot, brown rot and many other fungal diseases can be worse in plants with dense canopies, partly because of lengthened drying time and partly from lack of fungicide penetration.

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Pruning can physically remove pests or inoculum sources. Good examples are black knot lesions on stone fruit (photo), and fireblight cankers on pome fruit. If you remove and burn black knot cankers from plums and cherries, you’re not only removing potential inoculum to spread infections, but you are also likely eliminating lesser peach tree borers, too. They really like to bore into the “knots”. David Rosenberger reminded me that sometimes a lone, tall wild black cherry tree at the edge of a stone fruit block can have a black knot gall or two that is high up, and can easily spread infection into the susceptible trees. If you can’t reach the galls and cut them out, then maybe cutting down the tree would be a good idea. If this is beside an apple block, black knot galls would not pose a threat, and actually the tree is a source of parasites that attack our leafminers in apples.

Tent caterpillar egg masses are not common on trees sprayed with synthetic insecticides, but they are very common on backyard or organic apple trees (photo). They are shiny, dark brown, and encircle the twig. If you remove them before they hatch in early April, you won’t have problems from that pest this year. Do your gloves turn orange when pruning apple trees? If so, that suggests that you’ve encountered lots of European red mite eggs. I need a hand lens to see them… round dull red eggs, 0.15mm across, clustered near the buds.

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If you prune off lesions or eggs, do you have to destroy or haul them away, or is dropping them on the ground good enough? The answer varies. In New Hampshire, dropping mummified stone fruit to the ground is good enough. The spores of brown rot fungus can’t get airborne. But south of New England, it would be better to remove them from the orchard and burn or bury them. (Different types of spores survive down there.) To me, black knot lesions and tent caterpillar masses are things I’d prefer to see burned, rather than just dropped on the ground. Fireblight cankers? Get them out of the orchard, and burn or deeply bury. If they are small diameter, this isn’t as critical (they dry out more quickly.). Thicker diameter branches: more important to burn/bury.

I prefer to remove prunings from the orchard right away if possible, if deer have access. Otherwise I’d be inviting them to concentrate and feed there. Many orchardists now wait until the ground is relatively firm, and then run a tractor-pulled chopper over the prunings. Having picked up prunings by hand and piled them onto trucks, I can understand the attraction to chop the stuff.

Apple Grain Aphids — Don’t Spray!

Apparently spring will eventually come. When it does, and apple buds begin to open and show exposed green tissue, several pest events occur. One such event is that we see clusters of small, dark aphids on some opening buds. Almost all of them are apple grain aphids. These are on opening apple buds for a very short time, and do not cause a problem. Soon they move to other plants in the orchard. The “problem” to me is that some growers see them and immediately apply an insecticide, which is a waste of money, kills insect predators and parasites, and needlessly exposes the applicator to toxicity.

Tarnished Plant Bug

I’m expecting to see TPB’s at almost their usual population levels this spring, but I’ll be happy if the population is lower. They feed on fruit tree buds on mild, sunny days, especially if the snow cover has melted. Two or three days of sunny weather with temperatures in 50’s or 60’s really brings them out. As usual, orchards with lots of vetch, alfalfa or clover nearby typically have much higher TPB pressure than those with few such plants. Buds that are attacked by TPB usually ooze liquid for a few days. I find them in apple and peach orchards more than in other orchard trees. Maybe that’s just because those are our most abundant species of fruit trees.

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Is it worth spraying? You could answer that question yourself, by hanging several white sticky TPB traps in the edge rows of your orchard at silver tip stage. Hang them at knee height, near the branch tips, over a grassy part of the orchard floor. Then check them weekly and count up the number of TPB’s that you find. For apple growers with a good market for #1 fruit (like PYO blocks), a cumulative catch of 5 TPB’s caught per trap from silver tip to tight cluster makes it worthwhile to spray. If you haven’t reached threshold by tight cluster stage, you could wait and look again at pink. An average of 8 or more per trap by pink would warrant control. For people who aim to sell extra fancy apples, the thresholds are a cumulative catch of 3 and 5 per trap. I am relieved to note that many apple growers don’t bother to spray for TPB any longer. I think that is a good trend!

2014 New England Tree Fruit Management Guide

We still print this guide, with Cornell University doing the printing. There are relatively few printed, so the cost is relatively high. This year, they cost us a few cents under $36 each, so we are charging $36 per copy. We are not really set up to mail them out, so I plan to bring copies to meetings, and hopefully reach those who need them. If you are off the beaten path and would like one, let me know, and we’ll see if we can figure out how to get one to you. Once our copies are sold, the only way to get one would be to contact extension fruit staff in another New England state, & see if they have any left.

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Alan T. Eaton, Extension Specialist, Integrated Pest Management

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