University of Vermont

The main management items that should be on the minds of growers right now are disease management, groundcover management, disease management, and maybe some insect management. Canopy management probably needs to wait a little bit.

We have been seeing some symptoms of Phomopsis, a little black rot, and some downy mildew in the vineyards we have been checking in the Champlain Valley, not to mention the unsprayed vines on my deck arbor in central Vermont. The good thing about Phomopsis, assuming that you identify it correctly, is that there are no secondary infections during the growing season. Next year’s infections are caused by overwintering inoculum on canes and rachises from this year’s infections, but the disease does not continue to spread for this season. That means that Phomopsis-infected leaves may not need to be removed to prevent spread this year, but infected canes and wood needs to be removed and preferably burned before next season. Phomopsis is a greater problem issue in years with cool, wet springs. This season did start out cool, with just enough wet to cause some infections. Vineyards, especially if managed with organic practices, should have all diseased wood cut out by the beginning of vine growth. When in doubt, prune it out. Infections on rachises which occurred this past month may not be visible until veraison, so keep your eyes out.

With the relatively dry, cool weather (not counting this hot stretch we’re having this weekend) in June, black rot infection periods have been few, but if vines were not protected or high inoculum was present, we should be seeing lesions now. Black rot does have a secondary infection cycle, where conidial spores may be produced in active lesions, leading to continued infection throughout the summer. Black rot lesions are brown, often circular but with irregular margins, and may have a purplish halo at their margin. The key diagnostic is the presence of small black fruiting bodies, pycnidia, in the center of the lesion. These leaves should be regularly removed and destroyed any time you are passing through the vineyard, especially if you are using organic practices.

Downy mildew is just starting to rear its head. This disease is a little different than the others in that it’s caused by an oomycete, rather than a fungus. Consider it something like a cross between a fungus and a bacteria (I am oversimplifying, but the analogy works for me) in that it requires water to move, reproduces rapidly in warm weather, and forms lesions on leaves from which spores for the next cycle are borne. Downy mildew managemt picks up around now, as the summer heat, and especially warm rains, pop up. For organic growers, copper rotated with LifeGard may be a best option for management of this disease. For non-organic growers, captan, Revus, Ranman, and the Phosphorous acid fungicides (e.g., Phostrol, Rampart) are very effective. A great symopsis of downy mildew management is included in Dr. Katie Gold’s 2022 Grape Disease Control article (go to page 9).

Don’t ignore powdery mildew or anthracnose. The former is fairly easy to manage but easy to get away. If you see it, consider application of stylet oil or sulfur, but not both as they are a very phytotoxic mix. Same with oil and captan- keep those two at least 7-10 days apart in the vineyard.

Managing groundcover now is an important (potentially) non-chemical IPM tool to manage disease. Tall groundcover shades lower leaves and increases humidity in the canopy, which enhances the conditions for disease formation. If you do not have a clean strip (herbicide, cultivated, or mulched) under the vines, be sure to mow, including the strip between vines that the regular alley mower misses.

Some growers may be seeing grape tumid gallmaker, but for most, I don’t recommend management. For those who have it bad, Movento is a good non-organic material.

That should be enough for now.

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.

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.