Tag Archives: gypsy moth

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 8th. 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 31st. 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.

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 28th to 30th, 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.