At the UVM Horticulture Research and Education Center, we caught our first codling moth in our pheromone traps on Thursday, May 26. Using that day as a biofix, we start accumulating degree days (base 50°), or rather let NEWA accumulate them, and plan to apply a treatment at egg hatch. Most literature references 220 DD as the beginning of egg hatch, but the NEWA model suggests treatment just a bit later at 250 DD for most materials to improve efficacy and ensure that more larvae contact treated materials or surfaces. A second application would be applied 10-14 days after that to cover the entire generation. In order to reduce the likelihood of CM evolving resistance to specific spray materials, be sure to rotate materials so that no two successive generations receive the same class of material. There are a number of materials effective against CM, compared to the old days when organophosphates and pyrethroids were the first and often only materials to come off the shelf. Heather Faubert published a nice summary of materials effective against codling moth here a couple of years ago. Avoid using ovicides (materials targeted at eggs rather than larvae) like Rimon or Esteem at this time, as those should have been applied around 100 DD for best effectiveness. For resistance management, check the IRAC code on your material and be sure to rotate codes so that no two generations see the same material. This includes applications made against other pests, i.e., if you apply a neonicotinoid (IRAC 4A) against apple maggot in a few weeks, that also counts in your resistance considerations for CM. Since many growers rely on a neonic application for summer management of apple maggot, I suggest not using one now.

However, there’s more to the story. We have been trapping CM in some orchards in northwest Vermont and have seen widely variable catch numbers. At HREC, we have only caught that one moth, which indicates a low population in a pheromone-baited trap; at another orchard, over 40 moths have been caught. Unlike for some other pests, there is no “spray when you see X caught insects” threshold for codling moth. The rule of thumb is that captures over five to ten moths in a week suggests a high population that warrants two treatments per generation. However, a low population, as observed at HREC, may be treated with a single application at around 360 DD, or sometime next week.

This tailoring of spray application to the specific life stage of the pest, based on empirical scouting and use of accurate weather and pest models, is an excellent example of how modern IPM, using a combination of scouting, weather data, accurate models, and modern pesticide chemistries are combined to dramatically reduce environmental impact of apple pest management and likely save the grower a few dollars, too. If you’re not trapping but rather rely on the default ‘first catch’ date in NEWA or a general calendar-based timing, I do not recommend a single treatment for the first generation, you should default to two. Advanced IPM requires a thorough knowledge of your orchard and pest systems, you can’t just wing it, cut your sprays, and assume that you’ll get the best effectiveness.

Other things to think about: Nitrogen fertilizers should be wrapping up in the next week or so. All sprays should include a calcium product, and on bitter pit-prone varieties, you may want to consider making specific calcium sprays every 10-14 days until harvest. Keep an eye out for fire blight- we saw our first strikes this year on inoculated trees in one of Dr. Kerik Cox’s trials at HREC. Thinning should be done now- if you need a little more in high-value varieties hand thinning is the way to go. Scab should be done for most orchards aside from the cooler upland ones, so you could take a break in the Champlain and Connecticut valleys if you’re scab-free at this point and plan on next fungicide in a couple of weeks when the summer diseases ramp up.

Where trade names or commercial products are used for identification, no discrimination is intended and no endorsement is implied. Always read the label before using any pesticide. The label is the legal document for the product use. Disregard any information in this message if it is in conflict with the label.

The UVM Tree Fruit and Viticulture Program is supported by the University of Vermont Agriculture Experiment Station, UVM Extension, USDA NIFA E-IPM Program, and USDA Risk Management Agency.

UVM Extension helps individuals and communities put research-based knowledge to work. University of Vermont Extension, and U.S. Department of Agriculture, cooperating, offer education and employment to everyone without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or familial status.

We seem to be in a Goldilocks sweet spot in regards to moisture- just enough for the vines, not too wet to get work done. That can let some folks get complacent, but as vines are entering the immediate prebloom period, we are at peak disease pressure with all of the major diseases active to one degree or another. Every vineyard should be covered with the full suite of disease management products this week. That means mancozeb or captan plus a DMI, SDHI, or strobilurin (group 3, 7, or 11, respectively) material for non-organic vineyards; and sulfur plus copper (watch for incompatibilities on certain varieties, page 9 here) on organic vineyards. This would also be a good time to add biologicals, since we’re at ‘all hands on deck’ right now. Some materials, like Lifegard and Howler, are systemic acquired resistance promoters and need to go on a few days prior to infection. Others, like Serenade and Double Nickel, are biological extracts but can be mixed with other materials. Either way, these applications should be made a before infection, so spraying in the next day or two is a good idea.

Where trade names or commercial products are used for identification, no discrimination is intended and no endorsement is implied. Always read the label before using any pesticide. The label is the legal document for the product use. Disregard any information in this message if it is in conflict with the label.

The UVM Tree Fruit and Viticulture Program is supported by the University of Vermont Agriculture Experiment Station, UVM Extension, USDA NIFA E-IPM Program, and USDA Risk Management Agency.

UVM Extension helps individuals and communities put research-based knowledge to work. University of Vermont Extension, and U.S. Department of Agriculture, cooperating, offer education and employment to everyone without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or familial status.

Forwarding this great opportunity to the Vermont grower community. This would be appropriate for apple, grape, and other berry (e.g., bramble, blueberry, etc.) growers.-TB

Wednesday, June 29 3:00 pm – 5:00 pm Whitecliff Vineyard, 331 Mckinstry Rd, Gardiner, NY 12525. OR Thursday, June 30 3:00 pm – 5:00 pm Rulf’s Orchard, 531 Bear Swamp Road, Peru, NY 12972 George Hamilton, University of New Hampshire Extension Field Specialist Emeritus, will demonstrate the importance of and best techniques to calibrate air blast sprayers. Proper calibration will ensure effective, efficient, economical and legal spraying. Inadequate spray coverage is usually the cause of poor spray efficacy and additional spray applications. Overuse of some sprays results in unhealthy residues and can lead to fines. Calibration should be done several times each season, or when you incorporate any new equipment or repairs – from the tractor to the nozzle. Join us for a refresher or send new employees for training. This workshop is open for any grower that relies on an airblast sprayer to deliver plant protectants to fruit or vegetable crops. $20 per farm—Pre-registration is Required (Please list each person attending so that we have a proper count…space is limited) 2.0 DEC credits available in 10, 1A, 22, and 23 Register Here: https://bit.ly/calibratingairblastsprayers Agenda 3:00 pm – Welcome and Introductions 3:10 pm – Why are you Spraying and Benefits of Calibrating 3:20 pm – Calibration Factors Affecting Application Rate 3:35 pm – Pre-Calibration 3:45 pm – Sprayer Maintenance 4:00 pm – Calibration Notes 4:10 pm – Calibration Demonstration (water sensitive paper deployment exercise included) 4:30 pm – How to evaluate success – Understand deposition 4:55 pm – Q&A 5:00 pm – Adjourn ‌ CCE ENYCHP | enych.cce.cornell.edu ‌ ‌ ‌

Grapevines at the UVM Horticulture Research & Education Center are showing up to three to five inches of shoot growth, depending on variety. We are beginning to enter a critical time for disease management- all growers should plan on starting your spray program this week or soon thereafter (for inland growers with less growth). I pretty-well listed the strategies to take last week, so I’ll allow folks to look there.

Now is a good time to get out and clean up the ‘nubs’ left at the ends of spurs after pruning that will die out and serve as reservoirs for phomopsis and other diseases. While you’re at it, this is an especially good time to thin shoots. Cold hardy grapes trained to a high-wire trellis and in good health can support about six shoots per foot of canopy; select the best developing shoots and break off the others now while they are easily breakable with your fingers. Maria Smith and Dr. Michela Centinari at Penn State wrote a good summary of shoot thinning available here. I suggest reading it on the deck this holiday coming weekend with a nice glass of wine, and getting out in the vineyard next week to set this year’s crop on the right track.

As a reminder, all of my older IPM bulletins are archived on the UVM Fruit Blog.

Where trade names or commercial products are used for identification, no discrimination is intended and no endorsement is implied. Always read the label before using any pesticide. The label is the legal document for the product use. Disregard any information in this message if it is in conflict with the label.

The UVM Tree Fruit and Viticulture Program is supported by the University of Vermont Agriculture Experiment Station, UVM Extension, USDA NIFA E-IPM Program, and USDA Risk Management Agency.

UVM Extension helps individuals and communities put research-based knowledge to work. University of Vermont Extension, and U.S. Department of Agriculture, cooperating, offer education and employment to everyone without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or familial status.

Apple scab is still a concern in Vermont orchards. However, as heat gas continued to accumulate and relatively regular showers have provided for spore release from leaf litter, the supply of inoculum available to infect orchards, assuming you have prevented infection during these wetting events, is dwindling. The NEWA model in some sites shows up to 99% spore discharge by the end of this week, but like all models, we need to be careful as reality on the ground may be off by as much as 10%, which can be enough top cause infection. Bottom line- don’t let your guard down on scab yet, but this does look like an early-ending scab season. Stay covered and we’ll revisit next week.

Normally when we think of a cool / downright cold spell after a warm stretch conducive to fire blight, we consider the risk to decline with the temperatures. However, all of the usual fire blight models predict continued risk to blooming trees today and into this week. As there are fewer blossoms out there in many orchards (although inland/upland orchards may be in full bloom still), it may be easy to think that we’re out of the woods. However, I would consider treating high value blocks of young trees of fire blight-susceptible varieties, at a minimum (cider varieties, Gala, Mutsu, Cortland, Paulared, Northern Spy, Fuji, Macoun, etc). Word on the street has it that the streptomycin supply is low to unavailable. I’d suggest treating what you can with what you have, consider Apogee / Kudos even at half-rate to reduce shoot blight, and paying close attention to strikes as they show (and cutting them out aggressively).

Many folks are seeing the beginnings of petal fall and are considering an insecticide or thinning treatment containing carbaryl. Please reconsider that if you have any bloom, including in groundcover, in the orchard. I can’t in good conscience (nor legally, in keeping with the insecticide labels) recommend both treating blossoms with streptomycin while also applying an insecticide in a thinning program. So if you have blossoms but want to thin, I’d recommend NAA (Refine) or 6-BA (Maxcel) alone without carbaryl. This looks like a decent week for thinning.

Spray conditions look best tonight (Monday May 23) though Wednesday.

Orchards around the state are either in bloom (inland) or at/approaching petal fall (Champlain / Connecticut Valleys). This is always a tricky time for management, and growers may need to be ready to apply different treatments to different parts of the farm. Here’s my quick rundown:

Insects: Generally, there are still too many flowers out there- both apple blossoms and dandelions on the orchard floor to be spraying without impacting pollinators. In few cases is a pink insecticide spray needed, in my opinion, especially in retail-oriented orchards. Keep an eye on traps, and if you haven’t hung any yet, at least get your codling moth traps up to determine your biofix date. Point being: be ready to treat after bloom (and mow those groundcover flowers first), but don’t get knee-jerk. Wait and see, for now.

Diseases: Fire blight risk decreased this week with the onset of cooler weather, but is shooting right back up with this weekend’s expected heat. There are a lot of flowers still out there, even on petal fall-adjacent cultivars. Apple scab is primed with very high ascospore maturity. Any decent wetting event is likely to cause an infection, so keep covered with a protectant fungicide and use a single-site SDHI, Strobilurin, DMI, or combination material if you have any questions about coverage going into a wetting period.

Thinning: It’s looking like a heavy bloom year, so aggressive thinning is probably going to be called for. Plan on, at a minimum, a petal fall application, followed up by another at 7-14 mm fruit size. Successful thinning depends on many factors, I’ll highlight them more in light of upcoming weather in a few days. Be sure to adjust materials based on the NEWA Apple Carbohydrate Deficit Model. I’m also including Dr. Duane Greene’s advice from a recent UMASS Healthy Fruit Newsletter here.

“Bloom and Petal Fall Thinning

Duane Greene

Flower development has been erratic and proceeding in fits and spurts. However, it does appear that development in many orchards is approaching or will be at full bloom this week. The bloom and petal fall stages are excellent times to start your chemical thinning.

Bloom and Petal Fall

Bloom is a time when orchardists frequently do not choose to thin. The bloom period has not yet occurred so there is uncertainty about how favorable it will be for bees to fly. Also, the potential for frost still exists. However, it should be noted that the sooner you can start the thinning process, the better chance you have of influencing and encouraging return bloom. There are several options available to use at bloom.

Petal fall is a thinner time of application that most orchardists choose. The pollination period is known and there is a reduced chance of frost. If a bloom thinning spray was not applied a petal fall application of a thinner becomes very important.

With one exception (Carbaryl) the same hormone thinners can be used at either bloom or petal fall. When selecting a thinner(s) it should be emphasized that thinners are not as potent when used at bloom as when they are applied at the traditional 7-14 mm stage. A rough rule-of-thumb is that thinners applied at bloom and petal fall are about 50% less effective at thinning as they are if they were applied at the 7-14 mm stage.

Naphthaleneacetic Acid (NAA)

NAA has been used by growers for over 75 years. There is some comfort in using a compound that has passed the test of time. I routinely suggest application of NAA at 10 to 12 ppm. I have never over-thinned a tree using these rates. Lower rates will be less effective. NAA at 10 to 12 ppm could be applied to a broad spectrum of cultivars.

Naphthaleneacetamide (Amid-Thin)

This is a thinner that has garnered increased interest from growers recently. Amid-Thin is a weaker thinner than NAA and it rarely, if ever, over-thins. It has a reputation for being a reasonably consistent thinner. The label allows application of up to 8 oz/100 gal. I do not recommend using a rate any lower than 8 oz/100 gal. (Ed. note: Amid-Thin W is not currently registered in Rhode Island.)

Ethephon

Ethephon may be used as an early thinner. The recommended rate is 300 ppm or 1 pt/100 gal. Some have applied it at a rate as high as 400 ppm with good results. It may not be as consistent as other thinners but it remains a viable option. Since it produces ethylene it may also be useful to enhance return bloom.

Carbaryl

Historically, this has been the most popular thinner in New England. Unfortunately, it is very toxic to bees so it can not be used until the bees are removed from the orchard at petal fall.* Carbaryl is unusual as a thinner in that its effectiveness is concentration independent. It is routinely used at 1 pt to 1 qt/100 gal. Carbaryl is an excellent choice to combine with either NAA or Amid-Thin at petal fall to enhance thinning activity. I like the addition of carbarly with Amid-Thin to enhance the thinning activity of Amid-Thin.

Petal fall is a somewhat nebulous term. I consider it to be a period of time between the time petals fall from the flowers and when the receptacle starts to grow. Early in this period the receptacle is not growing, or growing very slowly, so there is little carbohydrate demand exerted by the fruit. Consequently, I generally do not pay much attention to the carbohydrate model during this period of time. However, when fruit grow to 5-6 mm then the carbohydrate model plays an important role in making thinning decisions.

Bloom and petal fall thinner applications are an important component in a comprehensive thinning program. This opportunity to help regulate crop load should not be missed. The real danger in bloom and petal fall thinning is not over-thinning but not thinning enough!”

Here’s what I’m putting on the orchard this morning: mancozeb @ 4 lb/acre (last application before switching to captan); Inspire Super (difenconazole / DMI) @ 12 oz/acre; Harbour (streptomycin) @ 1 lb/acre; Refine 3.5 WSG (NAA, thinner) @ 6 oz/acre / 15 ppm @ 100 gallons water/acre).

With the heat last week things moved fast, vines at the UVM vineyard range from bud burst to 1-2 inches of growth. It’s time to really be thinking about protecting vines from early season disease infections. Most cold-climate cultivars will not need disease protection until 5-8” of shoot growth, but any vineyards with heavy disease pressure last year and organic vineyards may wish to begin earlier, especially if inoculum reduction through thorough removal of diseased wood and mummy berries and/or dormant application of lime sulfur was not performed. I still recommend our fact sheet, An Initial Integrated Pest Management (IPM) Strategy for New Cold Climate Winegrape Growers as the best resource to boil the decisions down to a simple ‘prescription’, with the caveat that since it was written some new pest management materials have been released and inoculum may have increased in your vineyards which could lead to increased disease pressure. Growers should have an up-to-date copy of the New England Small Fruit Management Guide (on-line and hard copy versions) and/or New York and Pennsylvania Pest Management Guidelines for Grapes as a reference for specific materials, their efficacy, and use considerations. Remember however that the guidelines are written largely for vinifera and less disease-resistant hybrids, so the specific spray programs recommended may be overkill in Vermont vineyards.

The primary disease of concern at this point is phomopsis, as rachis infection at this point in the season is may cause significant fruit loss at harvest. Anthracnose may also be active at this point , given the warm/hot weather are expecting later this week. Vineyards that have had recent problems with those diseases or organic growers using copper or other less-effective materials may consider treating this week; if you haven’t had major problems with those diseases, treatment can wait until the 5-8” growth stage as long as you are using a highly effective contact fungicide like mancozeb or captan. Organic growers are in for a bit more work. The standard fungicides, copper and sulfur, have only fair efficacy against this disease at best.

It is worth noting that both copper and sulfur (including lime sulfur) can cause phytotoxicity on certain cultivars. Dr. Patty McManus summarized her research on copper and sulfur sensitivity in cold-hardy grapes in the 2/8/16 Northern Grapes newsletter, and I’ll summarize it to say that Brianna should receive no copper; and Frontenac (all types), La Crescent, Leon Millot, Marechal Foch, Marquette, and St. Croix should receive no more than 2-3 copper sprays per season. Save those for later when black rot and downy mildew become bigger concerns. Sulfur sensitivity was observed on several cultivars, and its use (including lime sulfur) is discouraged on Foch, Millot, Brianna, and Louise Swenson; with limited (2-3) applications suggested on LaCrescent and St. Croix.

I’d say any time now is good to get your shoots thinned down to 3-6 shoots per foot of canopy. Keep more on more vigorous vines, less on weaker ones.

Where trade names or commercial products are used for identification, no discrimination is intended and no endorsement is implied. Always read the label before using any pesticide. The label is the legal document for the product use. Disregard any information in this message if it is in conflict with the label.

The UVM Tree Fruit and Viticulture Program is supported by the University of Vermont Agriculture Experiment Station, UVM Extension, USDA NIFA E-IPM Program, and USDA Risk Management Agency.

UVM Extension helps individuals and communities put research-based knowledge to work. University of Vermont Extension, and U.S. Department of Agriculture, cooperating, offer education and employment to everyone without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or familial status.

I’ll be relatively brief, since everyone needs to do the same thing. With orchards at tight cluster to early pink bud stage (I appreciate everyone who is reporting their stages at this link), more significant heat, and a rain event expected late this weekend, we are looking at a double whammy of apple scab and fire blight infection events. Here’s me take, and it has a lot to do with your conditions and how quickly you can cover your orchards.

I don’t like spraying, especially fungicides, especially captan or sulfur fungicides, in the heat. If you can get a good coverage on in the next couple of days in the cooler parts of day, that would be helpful. Tissue is expanding rapidly now, so contact material that redistribute with rain would be useful tools to keep some coverage on. That would be captan or maybe sulfur (if organic), which may be a little too close to an oil (within 7-10 days) application to use. Next preference would be mancozeb, which tends to stick to plant tissues a little better. I would consider adding one of the more advanced single-site products in this spray to help with rust and powdery mildew as well- consider a strobilurin, SDHI, or DMI material, tank mixed with that contact material I just referenced. None of those are available to use in organic systems, so sulfur it is.

The plant growth regulator prohexadione-calcium (Apogee, Kudos) helps to reduce tree vigor at full rate, but even at ½ rate applied pre-bloom can help to thicken plant cell walls, which reduces susceptibility of growing shoots to fire blight. It would not be a bad idea to include this in the fungicide spray.

Fire blight protection needs to be applied to open blossoms 24 hours before or after a wetting event. Assume that you are in a full red alert infection potential after Friday, so any open blossom should be treated within a day of wetting. That means being ready likely Saturday or Sunday to apply first streptomycin (only choice I recommend if not organic) spray, if organic, I would consider alternating a ‘sanitizer’ like low-rate copper (Cueva, Badge, etc.) if growing for cider or russeted fruit are not a concern, oxidate, or low-rate (0.5%) lime sulfur followed up within a day with a biological like Blossom Protect, Serenade, or Double Nickel. Strep sprays should contain Regulaid or another wetting agent- that may exacerbate heat-related phytotoxicity from captan.

All of this is dependent on when your blossoms open vs when the rain comes. Some growers may want to put everything- fungicide(s), bactericide, wetting agent, PGR, into one tank. That’s doable but can be risky, especially in regards to phytotoxicity. Then again, that may be the best tactic at this point. Notice I did not mention insecticides nor foliar nutrients in these sprays. I don’t recommend either. For most retail-oriented growers, a little tarnished plant bug won’t affect you fruit value. For the few wholesale growers, you know if TPB has been a problem and have already been ready with a pink spray regardless of what I say. Given the state of pollinators and that the blossoms are right around the corner, I’d steer clear of insecticides unless you know you need one, and even then, do notapply if anything so much as a dandelion is blooming.

Start thinking about your thinning needs soon, but it’s too late for me to make any suggestion there, yet.

Where trade names or commercial products are used for identification, no discrimination is intended and no endorsement is implied. Always read the label before using any pesticide. The label is the legal document for the product use. Disregard any information in this message if it is in conflict with the label.

The UVM Tree Fruit and Viticulture Program is supported by the University of Vermont Agriculture Experiment Station, UVM Extension, USDA NIFA E-IPM Program, and USDA Risk Management Agency.

UVM Extension helps individuals and communities put research-based knowledge to work. University of Vermont Extension, and U.S. Department of Agriculture, cooperating, offer education and employment to everyone without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or familial status.