University of Vermont

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.

This is a big week ahead. Many orchards are at tight cluster bud stage, and with the warm and eventually hot weather coming up, bud stages are going to move fast. Anything you want to do prebloom should be done this week. That means foliar nutrient– zinc, boron, and nitrogen should be applied to improve bud and blossom viability. Oil may be applied for mite management, too, up to 1% up until tight cluster-early pink. But I would not mix oil with nutrients nor captan/sulfur. Nutrients are more important now.

With bloom and hot weather approaching, the biggest disease consideration – no scab is expected for the week with the dry weather, but apply a fungicide before expected wetting periods- is fire blight. This has the potential to be a big infection period.

Let’s look at the conditions required for infection:

1. Open blossoms.

2. Wetting. This doesn’t have to be a rain, a heavy dew or spray application could be enough to cause infection.

3. Heat during and after the wetting event. Later this week ‘they’ are predicting temperatures in the 80s with chance of thundershowers.

4. Build-up of sufficient population of the pathogen to trigger infection. This is known as the Epiphytic Infection Potential (EIP) and requires a) an overwintering or introduced pathogen source and b) heat prior to the infection that allows for that bacteria to multiply. NEWA models suggest that EIP sufficient for infection could be reaches statewide by Thursday.

Follow the NEWA model daily to best assess fire blight risk for your site.

I recommend that all growers with high-risk blocks (young trees of susceptible varieties, sites with a history of FB infection in the past couple of years) be ready to apply streptomycin to all blooming blocks.. Remember, a treated blossom is a treated blossom, so if an infection event extends more than 48 hours (you have 24 hours protection before and after the application time), you only need to re-treat if more blooms have opened.

For organic growers, streptomycin is no longer allowed by NOP standards. Some materials that may be effective include lime sulfur, which burns flower tissues so will only help a blossom that is already pollinated; low-rate copper materials like Cueva and Badge, which may russet fruit; and biologicals like Double Nickel or Serenade. None of those are as effective as streptomycin but each may be better than not treating at all in an infection situation.

I do want to mention another material that may provide some other protection. Apogee is a plant growth regulator that is applied around 1-3” shoot growth (i.e., now) that helps to shorten internodes and reduce the need for summer pruning. It also causes a thickening of cell walls that contributes to reduced shoot blight infection. For young, trellised trees where you may not want to stunt vegetative growth, some reduction in shoot blight has been found using ½ rates. The rate calculation for Apogee is fairly complicated and based on relative need for vigor control and tree row volume. Please see the label for more information.

Your best bet is to be ready to get a strep treatment on this week if you have any concern about this disease. For a good reader on fire blight, see: https://ag.umass.edu/sites/ag.umass.edu/files/fact-sheets/pdf/a4fruitnotesspring2015fireblight.pdf

This is the week to get your codling moth traps up. Traps should be hung at pink and checked daily until first catch is seen. That capture date will be the biofix you use when calculating degree days for subsequent management actions.

Finally, if you have irrigation, this is the week to make sure it’s running.

Stay cool.

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.

First, our colleague UMASS plant pathologist Dr. Elsa Petit is hosting a Zoom meeting for grape growers next Thursday, May 12, 2022, at 12pm. Click here to register. This 30-minute meeting should serve as a great introduction to Elsa and as an informal kickoff to the 2022 season.

At the UVM Catamount Educational Farms vineyard, buds were well-swollen on most varieties this week. Warm, and downright hot later next week, weather should trigger bud break in the days to come. I discovered while assessing the vineyard phenology that one small section of the vineyard had evaded my students’ shears, so we quickly wrapped up pruning that handful of vines, which is always challenging when the buds are so swollen and prone to breaking off.

1Marechal Foch ready to start the season. May 5, 2022.

Despite the dry weather ahead, it will get wet sometime and growers should be ready to manage diseases in the vineyard. We typically recommend fungicides starting around 5” shoot growth, but growers that have had more intense disease pressure may want to start earlier. That could come pretty soon if the warm weather pattern we’re heading into holds. There’s also supply chain issues that may delay availability of some materials. So whether you need mancozeb and captan or copper and sulfur, plan on ordering materials you expect you’ll need ASAP.

Continuing the tradition of the Cornell Grape IPM program, Dr. Katie Gold has again published a recap of season-long disease management considerations that should be required reading for all growers. It is heavy on conventional / non-organic recommendations, but there are recommendations and research results presented from her lab’s assessment of organically-approved biopesticides. Growers should also 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.

My graduate student, Bethany Pelletier, and I will be conducting a trial this season evaluating biopesticides and traditional organic materials (e.g., copper, sulfur) for disease management in cold-climate grape cultivars. Stay tuned for information from that work as the season progresses.

Finally, if you haven’t signed up for VitiNord, the premier cold-climate grape and wine conference which will be held this December in Burlington, please consider doing so. This is a big deal for the state’s and region’s wine industry, and the knowledge and networking shared will be huge.

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.

Orchards are at or around the tight cluster bud stage in 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 higfh 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 UVM Catamount Farm orchards, we were at late silver tip bud stage last Monday, April 18, when I applied a copper spray. Bud stage tracking is a critical IPM and general management tool to help track orchard activities that correlate to tree phenology. My observations that support these comments are often made from a single site at 200 feet elevation in South Burlington, or from one of the 2-3 trees at the edge of my yard at 1500 feet in Calais.

To better inform these notes, please consider reporting your bud stages. It’s really simple to bookmark this link on your phone and tap in the bud stage as you go about your orchard business: https://go.uvm.edu/22applebudstage

When I left the farm Friday, I noticed Zestar, an early-developing cultivar, were approaching the half-inch green stage, but the bulk of varieties were at a solid green tip. This is the time we start to really think about apple scab management, after that first copper application which is really more targeted at fire blight. Conventional wisdom has always said to maintain full protective fungicide coverage from green tip until all ascospores, the inoculum on last-year’s leaves on the orchard floor that cause primary infections, is expended around 900 degree days (base 32°F) from the green tip date. That’s one example of why knowing the dates of bud stage development allows us to fine-tune our pest management programs.

NEWA is the expert system of web-connected weather stations that we use in much of the northeast to help with IPM implementation. Every grower should have a nearby station or consider getting one. The data is as accurate as the weather is from your site to wherever the station is located. If you are interested in getting a station, please reach out to me. They run about $1500-2000, and last five years with minimal maintenance, maybe 7-10 years with some parts replacements. So for $200-300 per year, you can accurately implement IPM on your farm in a way you couldn’t without this critical information. The UVM Fruit Program covers the NEWA network subscription for the whole state. NEWA is a product of the New York State IPM Program, and is run by our colleagues at Cornell University.

After selecting a station from the dropdown list, various tools can be selected at the bottom of the page. If you set up a free account (you don’t need a station to do so), you can select a favorite station and preferred models that will show up at the bottom of the page. NEWA supports many crops besides just apples, so you may want to narrow down to the important ones to make it easier to check. Clicking on ‘Apple Scab’ brings us to a new page. Enter your green tip date- NEWA will guess based on accumulated degree days, but for our site, that was about six days early based on my observations. That will generate two tables- Ascospore Maturity Summary and Infection Events Summary. The first one predicts (that’s important- these are based on models and not observations in the field, but the models were developed based on extensive prior observations) the maturity of the spores that develop on overwintering leaves, from 0-100%. As spores mature and are wetted, they release and may cause infection if conditions are appropriate.

In ‘old IPM’, we would cover the orchard with prophylactic fungicides to prevent infection from the moment there was susceptible tissue, green tip, until a few weeks after petal fall, for a total of 8-10 or more sprays. Fast forward to ‘new IPM’ (skipping over a brief period in the 1990s when fungicides that had activity to be used after infection were used to arrest infection after it occurred but which also led to substantial fungicide resistance in the population of the scab fungus) where we can use the NEWA tools to fine-tune our apple scab programs.

I still recommend prophylactic coverage with protective fungicides- sulfur for organic growers; mancozeb early season or captan after bloom for non-organic growers, but tailored to your disease and orchard conditions to apply them with intentionality, rather than spray on a 7-day schedule. We also still have fungicide tools that have that retroactive activity of managing disease after infection occurred, but we want to minimize the potential for resistance development, so do not use them alone in that ‘backward only’ use. This allows multiple tools and conditions to be considered when developing our IPM tactics. For example, at our site, NEWA predicts 2-5% ascospore maturity, with some spore discharge later this week and likely conditions for infection (extended wetting). While best done by conducting a thorough assessment of disease in the fall, I feel comfortable in our orchard with not being covered for this relatively minimal disease event. However, in an orchard that had any substantial scab, and it takes very little to be substantial, 2-5% of a large overwintering scab population can cause substantial headaches moving forward.

This is a good thing, as I also discovered Friday that my spray tractor has a flat tire, and my spare spray tractor has a frozen clutch plate, which happens when it sits in winter and I wasn’t able to free up before I left. Our tire service company is short-staffed and can’t get to it repair until early this week, and my retired-since January staff mechanic won’t be popping inn to show me the trick to free the clutch until tomorrow morning. That highlights a key component of IPM- readiness to take action should a condition that requires treatment be found. I am lucky that, under my assessment of the IPM situation based on NEWA, that I have a week or so to get things in order, but it’s critical at this time of year to make sure your equipment and personnel are in top shape to get the job done. Using risk management tools like NEWA to make nuanced decisions means living a bit on the edge- being ready to hop on the sprayer at short notice, and constant checking of the actual orchard situation though scouting and the modeled environment through daily NEWA checks.

Other orchard activities to think about: clear up any remaining brush and consider a close to the trunks, low to the ground flail mowing to reduce debris and overwintering scab inoculum; hang white sticky traps for tarnished plant bug, if that pest is of concern (pick-your own growers typically don’t need to worry about this cosmetic pest), get traps ready to hang at tight cluster-early pink for European apple sawfly; apply herbicides if you are using them; get irrigation up and running; order fertilizer.

After what felt like a long winter, it seems safe to say that spring is around the corner. I hope everyone’s pruning season is going well, this is the home stretch for sure. I often recommend that growers look for bud damage before commencing final pruning to adjust for buds that may have been killed over the winter. We have not completed our bud assessments at the UVM vineyard yet, and have seen little damage in recent years, given the cold-climate cultivars that we grow. That said, I am a small bit concerned about the low temperatures we observed in late January and February, so I’ll be doing some bud dissections this weekend. Stay tuned.

Pruning and early season sanitation aren’t just horticultural practices, but also form a critical foundation for early disease management on the vineyard. Inoculum for several diseases overwinters on diseased wood, stems/rachises, and mummified berries, and those should all be removed and burned or otherwise destroyed / dumped well away from the vineyard. As the Vermont grape industry is hovering around the 25 year mark, many vines are getting older and you may consider renewing older wood by replacing trunks and cordons where appropriate.

Once dormant pruning is done, it is not a bad idea for vineyards that had Phomopsis or anthracnose or that will be managed organically to receive a dormant application of liquid lime sulfur. I discuss this material in a prior post, and it deserves extended discussion as it is not only very effective in reducing overwintering inoculum, it is also very caustic and among one of the more acutely dangerous pesticides I have ever used. That said, it is very useful and could be a primary tool for the growing field of organic / biodynamic / ’natural’ viticulture.

On that note, expect more material in coming days on these alternative production practices. The UVM Grape program has long promoted an effective, relatively low-input, but certainly ‘conventional’ (I don’t like that word, and prefer to use ‘non-organic’) program for disease and, to a lesser degree, insect management in vineyards. A substantial portion of the Vermont industry, however, is growing grapes under, for lack of a better term, ‘natural’ management programs that take inspiration from organic and biodynamic practices. This is somewhat new practice for me, although I have worked with organic apple systems for over 15 years. The cold-climate grapes that we grow present a unique opportunity to implement such practices, since they are generally more disease-resistant than vinifera and even older French American hybrids. My graduate student, Bethany Pelletier, and I are beginning an intentional focus on supporting this style of production. Expect to see the results of our recent survey in a bit that may help us to define just what ‘natural’ viticulture is, and to hopefully come up with a name and definition we can agree on.

December 4-7

I’d like to end with a plug for growers to register to attend the VitiNord 2022 conference, which will be held in Burlington December 4-7. This is a big deal. VitiNord is the world’s premier grape and wine conference focused specifically on cold climate production. It alternates every three years between Europe and North America, and we are truly honored to be hosting it. Registration is open now, and is discounted at least until the end of the month. Thanks to a grant I procured from the Vermont Agency of Agriculture, members of the Vermont Grape and Wine Council receive a further discount, but those are limited, so plan on booking soon. To join the council, contact them here.

Stay dry,

Terry

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.

Hello everyone:

There are two regulatory issues happening now that apple and grape growers should keep an eye on and consider getting involved in the process.

1. The first is a bill in the Vermont legislature, H.466, which has already passed the house and is in the Senate Natural Resources committee this week. This bill would set up a monitoring and potential licensing program for agricultural users of surface waters for irrigation. As with most such regulations, there is a minimum threshold below which there is an exemption, and in this bill is set at 5,000 gallons per day. For anyone who irrigates, it’s not hard for even a small operation to use that in an hour.

Here is a link to yesterday’s bill walkthrough in the Senate Natural Resources & Energy committee: https://youtu.be/vujZggH6EmY?t=4140.

The walkthrough is about 10 minutes long, from 1:09:00–1:19:35.

It’s next on the cbray) and the Committee Assistant Jude Newman (jnewman) to testify.

2. At the Federal level, comments are open on a rule within the Food Safety Modernization Act that would provide more flexibility for farms to comply with water testing requirements. The new rule would replace required frequent testing (and treating, if necessary) of waters used for irrigation, foliar sprays, and other preharvest uses with a risk-based protocol. While potentially more flexible, this system would also involve growers’ developing and adopting a time consuming and difficult process to evaluate the safety of waters used in crop production. The Vermont Agency of Agriculture, Food, and Markets and Vermont Tre Fruit Growers Association are preparing a comment and are soliciting input from the grower community.

More information on the draft rules can be found at: https://agriculture.vermont.gov/produce-program/fda-announces-proposed-changes-agricultural-water-requirements-produce-farms. As mentioned there, these rules affect farms that are “covered” by the Produce Safety Rule under FSMA. Generally, those are farms with gross sales over $500,000 who sell produce on the wholesale market, although the definition is a little me complicated than that.

If anyone has questions or comments, please let me know and I’ll do my best to answer them or pass on to the appropriate person.

Thanks,

Terry

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