University of Vermont

Vermont orchards and vineyards are in varying states of vulnerability and likelihood of frost damage going into tonight’s expected cold event. At UVM orchard in South Burlington, we are at about 50% petal fall on McIntosh and the vineyard is at about one inch of shoot growth; inland and upland orchards are at or even approaching full bloom and vineyards are hovering around bud break. All orchards in the state are at risk for blossom tissue damage with temperatures at or below 28°F, and potentially a full crop loss around 24-25°F. Vineyards with fully emerged buds (1-2 leaves or more) are at the same risk, but those at bud burst or behind are less susceptible to damage and may do okay even into the lower twenties. In the Champlain and Connecticut River Valleys, expected lows are in the 30-32°F range, and orchards should be okay except possibly in low-lying pockets. Inland and upland, this event will likely show where site selection leaves orchards at most risk. Some inland orchard sites are calling for lows in the 24-25° range- that could cause substantial damage. Winds are expected to calm down overnight which lends to increased frost risk in low areas where cold settles. This does mean that methods that stir up air inversions may help- wind machines, helicopters, etc.- but few of our farms are set up for that aside from the lone wind machine I know of in Shoreham which I expect will be running in the early hours of tomorrow morning. There is little you can spray to affect frost tolerance of plants- some materials like some copper formulations and some potassium fertilizers are either labeled or purported to improve bud hardiness but not when sprayed right during a cold event and the science isn’t very good on that, either. Not to mention that sprayers will be icing up if you try to spray at 10-11 PM or later when the winds calm down, as that’s when the cold (below 32°, when spays will start freezing) is expected.

Growers could try burning round bales in the lowest / coldest parts of the plantings, starting around midnight or whenever the temperature starts to get down to 28°, but that isn’t known to be especially effective as the heat needs to radiate across a large area to really have any effect, and the smoke and near-range heat from burning bales can damage developing buds. If you have a Frost Dragon or similar device, tonight would be a good time to run it. But who has one of those in Vermont (I’d love to hear from you if you do).

The best case for most may be to wait this out and to conduct an assessment tomorrow afternoon or Friday. This article provides some good pictures of damaged tissues to compare yours against.

https://www.canr.msu.edu/news/assessing_frost_and_freeze_damage_to_flowers_and_buds_of_fruit_trees

Understanding the extent of damage will help with reporting for crop insurance purposes or to adjust you fruit (apple) or shoot (grape) thinning needs.

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.

Good afternoon. UVM Fruit Program M.S. student Bethany Pelletier has written this week’s message. -TB

For many of us, bud break came up quick here in the Champlain valley. This means a real push to make sure your pruning has set you up for a clean, orderly season (or as much as we can hope). Make efforts to get your vineyard as sanitized as possible, getting old wood cleared and well away from your working plants to reduce as much of last year’s inoculum as possible. Fungal disease loves to sit in that old grape wood, so leaving it laying in the vineyard can have you fighting an uphill battle.

Speaking of inoculum, get your sprayers ready! Those with organic spray programs or with heavy disease pressure from previous years will want to begin your spray program around 3” of growth. For us here at the UVM Horticulture Research and Education Center, this likely means a spray sometime next week before a rain event. For those with a good handle on your disease pressure and using highly effective fungicides, you can get away with waiting until 5-8” of new growth.

As for what to spray, keep in mind what we are working against. Our key early season disease is Phomopsis, but we’re keeping in mind any downy mildew or black rot as well. Anthracnose is also an early season disease, and while not present in all vineyards those who have it should also be spraying for it at this time. Key fungicides in your arsenal against these early season diseases may include mancozeb, captan, or ziram. For organic growers, copper has shown some efficacy, but good sanitation practices are really your first line of defense here.

With nervous excitement, I am happy to be starting this next season of grape growing! I wish a sunny and not-so-rainy spring to you all! -BP

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 are expecting a slight warmup later this week that may push levels of fire blight bacteria high enough to be concerned about infection in blooming orchards. While this event does not look like a ‘high alert’ scenario, and chance of rain is relatively low but still there for Friday, all growers with trees in bloom should keep an eye on NEWA and be ready to treat orchards with open blossoms with streptomycin ahead of an infection period. Apple scab continues to look like a non-issue for as far as the forecast goes, but be prepared to be fully covered before the next significant rain event. NEWA is not suggesting that the low-likelihood, short duration rain that might come tomorrow Friday May 12 will be enough to cause an apple scab infection period. My take- hold off on spraying unless you are in a high fire blight risk situation and you get wetting tomorrow, then apply strep. There’s no need for fungicide at this time but we’re just getting into the season with plenty of spores left to discharge due to the dry weather. The next good rain will likely result in a big infection period and, with the rapid growth we’re seeing at this time of the year, you want your spray coverage as close to the infection period as possible to ensure that new growth is covered.

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.

Buds have been breaking in Vermont vineyards in the past week, which signifies the real start of the growing season. This brings up a few pest management considerations for your vineyards. Most cold-climate cultivars will not need disease protection until 5-8” of shoot growth, but any vineyards with heavy disease pressure last year may wish to begin as soon as shoots are 3” in length, especially if inoculum reduction through thorough removal of diseased wood and mummy berries and/or dormant application of lime sulfur was not performed. Since we all likely have a week or two before we need to get out there, now is a good time to make sure that your equipment is ready to go. I still recommend our Initial IPM Strategy for Cold Climate Grapes 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 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 warm weather in the next few days may increase emergence of grape flea beetle or cutworms. Grapes are susceptible through about the one inch shoot growth stage, so this could be a short window and the vines may well outgrow any threat pretty quickly. A scouting of your vineyard for feeding on swelling buds or developing shoots may be warranted. If damage is evident on more than 2% of buds, an insecticide treatment may be warranted. But if shoots expand rapidly over the week, don’t worry about this pest.

Since buds at ground level have begun to emerge, applications of systemic herbicides should either be halted or very carefully controlled to prohibit contact with green tissue. Now is an appropriate time for cultivation in vineyards to manage weeds. It’s also a good time to keep water on newly planted or young vines. With soil warming and growth beginning, nitrogen fertilizer applications, if needed based on foliar analyses or observed low vigor last year, may also be made now.

With orchards in the Champlain and Connecticut valleys heading into bloom now and even inland/upland orchards expected to show some blossoms later this week, it’s ‘go-time’ for setting up the 2023 Vermont apple crop. We are thankfully looking at an incredible week- sunny and 60s or 70s every day as far as the outlook goes, and cool but not cold nights expected, no rain. If ever there were a Goldilocks bloom season, this is it.

It goes without saying but I will say it that we don’t need to be spraying any insecticides heading into bloom. If you are at early pink stage at the latest and if you have a documented population of tarnished plant bug or European apple sawfly and if your markets can’t absorb a little cosmetically-damaged fruit (i.e., if you sell to wholesale markets) and if you have mowed all flowering weeds like dandelions that would be bringing pollinators into your orchard now , then a low-residual non-systemic (i.e., non-neonicotinoid) insecticide may be applied to manage those pests- but that’s a pretty small Venn diagram I described. Given the dry weather, I don’t see any need for a fungicide, assuming that you were covered during last week’s long apple scab infection event. The cool weather looks to be keeping fire blight bacteria at a low epiphytic infection potential so we can’t expect that disease to be an issues- but pay attention to NEWA this week as the bacteria that causes the disease can rapidly multiply if the weather warms and open blossoms would need treatment with streptomycin or a biological material (Blossom Protect, etc., only recommended for organic orchards as the efficacy is much lower than strep).

This is a good week to get irrigation going. This would also allow for fertigation of important nutrients, especially nitrogen and boron that are in high demand with the flush of new growth we see at this time of year. Finally, I hope to see some of you at the Apple Pollinator Workshop at 4:30-6:30 on Wednesday, May 10 at the UVM Horticulture Research and Education Center, 65 Green Mountain Drive, South Burlington VT.

Apple meeting agenda for 5.10.2023 twilight meeting.pdf

Good afternoon:

I returned very tired from my conference in Spain with a realization I that I needed to get into the orchard to get a scab spray on, as it had been ten days since I treated the orchard when we were just at green tip. Needless to say, we are in full scab management season with ascospore maturity creeping up, and significant wetting, especially like we saw today, that can discharge a lot of spores. Hours required for infection to occur are relatively low with the temperatures in the 50s that we are seeing this week. Fungicide coverage should be maintained during this wet week, and a material with kick-back activity (FRAC codes 3, 7, 9, 11- be sure to rotate among these!) applied should you have any question on coverage of protectant fungicides. Use of these materials should help with management of other diseases, including powdery mildew and cedar apple rust, as well.

For the time being, I’m pretty confident that we can consider fire blight a non-issue heading into bloom. That can change quickly should things warm up. Insect management should be on your mind, though. This is also a good time to get your first soil-applied nitrogen fertilizer down. In many cases, split applications are more useful than a single application, timed at tight cluster to pink and a second application at petal fall. Without a foliar analysis (which is always the gold standard for developing fertilizer recommendations), growers should err on applying a total of 30-40 pounds of actual nitrogen per acre whether in one or two applications.

Many growers know that I am generally not in favor of insecticide sprays at pink unless scouting indicates a need because of the residues that would be present for pollinators to be exposed to at bloom. But this is a great time to be monitoring pest populations to be prepared to manage them when the time comes. These comments are from my graduate student Eli Wilson, who is implementing a scouting program with a subset of growers:

Hi folks,

We’ve entered May and while I am sure apple scab is on your mind it is also time to start thinking about putting your dog wood borer traps out.

Also, if you have not yet set out your sticky card traps or recorded your scouting data for Tarnish Plant bug then please do!

Here is what you need to know about the dogwood borer (DWB):

Identification:

The adult form of the dogwood borer is a small, clearwing moth that is shown in the image below. They have approximately a 1-inch wingspan and have a black and yellow color pattern making them resemble wasp. They have mostly clear wings with circular windows at the tips. The larvae of the dogwood borer (DWB) are about ½ inch long and can range from white to light pink with a large brown head.

This is the time of year that the adult dogwood borers begin laying their eggs in the crevices of tree bark, so it is important to be monitoring for their presence in your orchard.

Damage:

The dogwood borer larvae are the ones that cause the damage, feeding on the phloem and cambium layers of the tree. Signs of an infestation may first appear as a pile brownish red frass on the outside of an entry hole in the tree trunk. While a few borers will not cause significant damage a population can build over the years and lead to reduce tree vigor and even girdling. An image of the larval form of the dogwood borer (DWB) is also shown below.

Trapping:

You will be using two of the six orange TRÉCÉ PHEROCON VI DELTA TRAPs to monitor the dogwood borer in conjunction with one of the provided lures that are labeled “DWB”.

The lures should be replaced every 4 weeks and you can replace the stick liners every week if you choose. If you do not replace the liners each week, be sure to remove all the trapped dogwood borers after recording that week’s catch total.

The orange Delta Traps should be hung within the tree canopy at approximately 4-feet off the ground as shown in this instructional video: Hanging Delta Traps

I hope this information is helpful, if you have any questions, comments, or concerns please feel free to reach out!

Happy trapping!

Best,

Eli Wilson

Greetings growers,

I hope this message finds you well. At UVM Extension we have been working on an upcoming in person apple grower workshop to be held in Burlington during the anticipated apple bloom period. It is the first of two on pollinators in fruit production.

Supporting and Monitoring Pollinators in Apples, 4:30-6:30pm, Wednesday May 10, UVM Horticulture Research and Education Center, Burlington VT

Supporting and Monitoring Pollinators in Blueberries, 5:00pm-7pm, Tuesday May 23, Cedar Circle Farm and Education Center, Thetford, VT

I have attached a flyer and the apple meeting agenda for more details. There will be 2 pesticide applicator credits and 1.5 CCA CEU available with meeting participation. Thanks so much for considering and hope to see you there.

Kindly,

Laura Johnson

University of Vermont, Extension Pollinator Support Specialist

https://www.uvm.edu/extension/pollinator-resources

Laura.O.Johnson

327 US Route 302 Suite 1 Berlin, VT 05641

Cell: 802-291-2118

FINALpollinators-workshops-02.pdf

Apple meeting agenda for 5.10.2023 twilight meeting.pdf

I am leaving for a research conference for the next week, so I am getting out a preemptive notice of things to watch for while I am away. So, while I am discussing disease management, remember to check NEWA to assess actual disease conditions before applying prophylactic sprays in your orchards.

Bud stages have moved pretty rapidly in the past ten days, and we are a good 7-10 days ahead of ‘normal’. In many years I start spraying the orchard on or around earth day. This year I started April 13, and put a second spray on this morning to buy some protection while I’m gone for a week. If you have the notion, you can report your bud stage dates at this link (https://go.uvm.edu/23applebudstage) to help me keep an eye on things around the state.

Orchards are at or around the tight cluster bud stage in Champlain Valley of Vermont, which means that there is plenty of tissue out there for apple scab to infect, and the disease is in a critical management phase. Orchards should be covered with an effective contact fungicide (mancozeb, captan, sulfur if organic) going into any expected wetting periods. If coverage is questionable going into a wetting event, a postinfection material may be used- Vangard is effective prebloom and during relatively cool weather. There are several others, too- see the New England Tree Fruit Management Guide apple spray table for details. Note that these post-infection materials, including DMIs, SDHIs, Strobilurins, and Anilinopyrimidines, have high potential for the fungus developing resistance to them, so always mix with a protectant and rotate fungicide classes every application. Organic growers have fewer options for postinfection materials. I am not recommending liquid lime sulfur anymore, as it is just too caustic and dangerous to applicators, trees, and equipment. Some materials such as the peroxide (e.g., Oxidate) and bicarbonate (e.g. Armicarb) based fungicides have shown efficacy when applied during infection, as the spores are germinating on wet leaves, but are pretty limited in providing any real control after cuticle penetration has occurred. Bottom line: keep the orchard covered.

There is still time to apply oil to manage mites and scale. I am a proponent for putting oil on as late as possible, up to tight cluster or even pink. The rate should be adjusted down as buds open more: 2-3 gallons per 100 gallons water (straight % in tank, not adjusted for tree for volume or per acre) is good from dormant through green tip; 2 % GT-tight cluster; and 1% as you approach pink. Oil should be put on dilute- slow down and open up your nozzles if you can. For most orchards, 100 gallons of water per acre should be the minimum for applying oil. That means recalibrating your sprayer in many cases.

Trees are approaching their peak energy needs as bloom approaches. Now is a good time to get your first soil-applied nitrogen fertilizer down. In many cases, split applications are more useful than a single application, timed at tight cluster to pink and a second application at petal fall. Without a foliar analysis (which is always the gold standard for developing fertilizer recommendations), growers should err on applying a total of 30-40 pounds of actual nitrogen per acre whether in one or two applications. This is also a good time to apply the foliar tonic of urea (3#/100 gallons), boron (1# solubor or 0.1-0.2 lb actual B/100 gal) and zinc (many materials, use label rates). I wouldn’t mix this tonic with oil, do one and then the other in this next spray or two if needed.

At this time of the year, we should always be keeping an eye on the weather in the week ahead, and the shift toward warmer temperatures this week suggests that we may be seeing the first signs of green tissue on trees in many sites in Vermont. Green tip indicates the beginning of the growing season, and is an important biofix for apple scab models. Keep checking your trees daily and note the date when 50% of buds on ‘McIntosh’ have opened enough to see green tissue from the side. That date should be used in NEWA to mark your biofix for apple scab ascospore maturity.

Potential for apple scab infection increases with temperatures as more ascospores mature to be released in rain events. In the early season. Not many spores are mature, and if you had good scab control last year, i.e., no visible lesions all season, then the small percentage of mature spores in a low inoculum situation may give you some early season breathing room. But if you did have a problem with scab last year, or a neighboring orchard harbors substantial inoculum, you should be ready early in the season to protect your trees. Copper is the standard, first spray of the year in virtually all orchard, as it helps to reduce fire blight inoculum and is a moderate fungicide against scab that can cover the first infection event for that disease.

But copper is a tricky material- it must be on the plant and not washed-off by the time fire blight cankers are oozing with the onset of warm weather, but if applied too late, copper ions on developing buds can cause fruit russeting. I would plan on applying copper to any orchard that had any amount of fire blight last year and which is showing green tissue or at least solid silver tip as soon as you have a suitable spray window. If possible, I would plan on applying copper to any orchard, period, that is between silver tip and half-inch green in the next 7-10 days. There is a pile of materials out there and for all intents and purposes for this delayed dormant spray any of them are effective as long as you are applying a good full rate of copper ions. The standard dry materials like Champ, C-O-C-S, Cuprofix, Kocide, etc. will give you the best bang for the buck here, and I would apply the full label rate for any of them and thoroughly spray the whole orchard. The only caveat I offer is if phenology advances rapidly before you can get out there and the trees are at 1/2” green tip, in that case, I would apply a low to middle rate. After 1/2” green tip, unless you don’t care about fruit finish (e.g., cider fruit), I would avoid copper.

This isn’t a bad time to get oil on, either, but the rate should be 2% by volume and coverage absolutely thorough to soak overwintering mite eggs, scale, and aphids. If time is of the essence, focus on copper first.

There is still time to do some sanitation in the orchard by flail mowing leaves and fine brush, and/or applying a coarse urea spray (44 lb feed grade urea in 100 gal water applied per acre, directed at the leaf litter) to speed decomposition and reduce apple scab inoculum.

Keep an eye on NEWA regularly as we enter into the 2023 season. Up-to-date spray tables may be found in the New England Tree Fruit Management Guide available online at netreefruit.org and shortly in hard copy format.

I am writing a somewhat rare joint apple-grape bulletin today to start off the 2023 season. This year marks my 29th season growing apples in New England, and 18th (I think) growing grapes. That’s a long time to be at it, when just before that I was convinced that I left farming behind when I left the dairy farm and headed off to college. Such is the way things go. I hesitate, however, to continue to call myself a farmer, particularly as the letters after my name and number of words in my title grows. Suffice to say that, despite the changes in duty I’ve had over the years, I remain committed to Vermont specialty crop growers, and look forward to the season ahead. My former colleague and mentor Lorraine Berkett always said we needed to be ready for the growing season by April 1. Like many, I am not ready, but the season will come to us as it does, and I plan to use these notes to help us all get through it together.

This season I have an excellent team working with me on both crops that I have research and Extension responsibilities for. My two graduate students, Bethany Pelletier and Eli Wilson, will be helping me out both by conducting their own research and teaching activities and by helping to be eyes and ears on farm both with me and with undergraduate students we will host this summer. You can expect to see their bylines a bit as they share their experiences with the community. I also have a new operations manager at the farm, Brian Vaughan, who will help me out with spraying and other work at the UVM farm, once we get him set up with his applicator’s license.

Speaking of pesticide rules, the Vermont Pesticide Rules were updated for the first time in over 30 years this past winter and the new rules went into effect in February. Every grower should review the rules here. The changes are a bit too long to summarize here, but include standardization of classifications; new rules for applicators; new standards for recordkeeping; standards for protection to pollinators (or particular interest to fruit growers, more to come on this); and changes to transportation and storage requirements. A summary of the regulation changes may be found in the Spring 2023 Vermont Pesticide Applicator Report, starting on page 3. That report also includes a refresher on the updated Worker Protection Standards rules that you should refresh yourselves with before the growing season commences.

I will put in a separate and distinct comment here- I don’t care if your operation uses organic, non-organic, or other materials, becoming a licensed applicator ensures that you have been trained, maintain training, and are tested on your knowledge of safe use of agricultural chemicals. Everyone in our community should be trained, licensed, and hold ourselves to the highest standards to maintain environmental quality and ours’ and our workers’ and families’ safety as we protect our crops.

I’ll wrap up with a suggestion to get your ducks in a row for the season that will rapidly be here. Besides getting up-to-speed on regulations and requirements, we should be cleaning, testing, and calibrating our sprayers; checking and ordering inventory; finishing up pruning; performing orchard and vineyard sanitation by shredding leaf litter and brush; and getting set up with a weather station and monitoring program for your farm so that you can make informed and wise decisions rather than rely on gut instinct in the season ahead.

Here’s to a good spring and great growing season overall.