University of Vermont

Happy (official) summer. We’re still in peak diseas management mode on Vermont vieyards, but things are starting to shift a bit. Phomopsis management should be done, but black rot is still a concern as fruit won’t develop resistance to that disease for a couple more weeks. More importantly, ‘the mildews’ (downy and powdery) are a concern. For powedery mildew, which only requires high humidity to cause infection, sulfur, Regalia, and stylet oil are options for organic vineyards; those and the strobilurin (FRAC class 11), DMI (3), SDHI (7), and AP (9) are options for non-organic vineyards. Downy mildew is in another whole biological class of diseases, and organic options for management include the copper materials, Serenade Max, and various potassium bicarbonates; non-organic producers may use a strobilurin, phosphite product, captan, or Revus. The New England Small Fruit Management Guide summarizes these options in a pretty easily-digestible table.

I am deep in the midst of teaching two summer courses now, including my Cold Climate Viticulture course. Tuesday I gave the students a tour of the UVM vineyard, which I hadn’t walked in a good week or so, and was taken aback by the amount of Phomopsis and black rot I saw on some vines. Closer examination revealed that the diseases were restricted to the bottom 2-4 leaves on the shoots. This generally indicates that there was an issue with application when those leaves were sprayed, as I checked my spray records against the NEWA grape disease models and I was pretty well-covered. Last year we installed a new exclusion netting system that we left up on the wires, which my tractor with spray cab won’t fit under. So, we pretty quickly set up an old sprayer for use on one of our other tractors, and while spraying that first time, I was tweaking many aspects of the operation while making my spray– travel speed, fan speed, nozzle orientation, etc. I also noticed that one nozzle had some grit in it and likely wasn’t getting material on like I should have. Lesson learned: calibrate your sprayer and check coverage before you start the season.

We also noticed that my vines were a little yellow, and pretty much begging for some nitrogen. This is a good time to get a last, light dose of nitrogen on your vines before putting it away for the summer so vines can adequately shut down before winter. This is also a great time to apply potassium and magnesium as your soil and petiole tests call for them.

Any time now the bases of shoots will start to lignify and we can start shoot positioning in earnest. Vermont summers are short and relatively cool, and developing and ripening fruit clusters need as much sun as you can give them. That starts with getting the clusters exposed by combing shoots down on high-wire trained vines so fruit are exposed and leaves are more or less under the fruit zone. Low-wire or vertical shoot positioned vines need their shoots directed up and away from developing fruit, again to minimize shading. Make sure shoots aren’t breaking off as you work with them, and if they are, wait a bit to do this. We’ll post more information on this shortly.

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.

Happy summer:

Apple scab should be pretty much done by now, but be sure to look carefully to ensure that you haven’t had any slip through, as it was certainly windy during a couple of the infection periods this season. If you find no scab in a thorough evaluation of the orchard, that disease is done for this year. Sooty blotch and fly speck (SBFS)would be next on the management agenda, and typically require 270 hours of accumulated wetness starting at 10 days from petal fall. For reference, accumulated wetness in Shoreham (according to NEWA) is about 125, with similar values for other Vermont orchards. Keep an eye on this and apply an appropriate material ahead of any rains as we near the threshold. Honeycrisp growers in particular should also plan on applying a material with efficacy against black rot, which that cultivar is uniquely susceptible to. Common summer fungicides targeted against these diseases include captan in combination with Topsin, a strobilurin (Flint / Sovran), or a DMI (Pristine, Inspire, etc); organic growers may consider Regalia, sulfur, or Serenade, but I am not really sure of theis efficacy. I will say that in 12+ years of managing an organic orchard with a primarily sulfur-based program, I saw almost no SBFS, but plenty of black rot on Honeycrisp especially. Take that as you will.

We’re in a calm spot between insects, but it is time to hang you apple maggot fly (AMF) traps. These are some of the easiest pests to manage using an IPM strategy, so there’s really no excuse. The idea is to assess the population in the orchard before applying prophylactic sprays. By using red sticky traps, you can time treatments for best effectiveness, and maybe even skip treatments if the populations are low enough. Traps are red plastic balls that you coat with Tanglefoot adhesive. Kits including traps and adhesive are available from Gemplers and Great Lakes IPM.

Traps should be hung at least four per 10-acre block, preferably at the orchard perimeter and especially near sources of the insect, like wild or unmanaged apples. Placement in the tree should be about head-height, and surrounding foliage should be trimmed away- this trap is largely visual, and you should be able to see it from 10-20 yards away. The traps may be baited with an apple essence lure that improves their attractiveness dramatically. For monitoring to time sprays, unbaited traps that catch one fly per block (as an average of all the traps in the block) would warrant treatment; the lure makes them much more attractive such that you can wait until an average of five flies per trap are caught before treating. For most growers, the main insecticide used against AMF is Assail, Imidan also works but it has a long reentry interval and tends to leave visible residue on fruit. For organic growers, Surround works well, but its use in midsummer may increase European red mites, and it can be hard to remove at harvest; spinosad (Entrust) works pretty well too. First AMF treatment is still a few weeks off, most likely.

Think about including calcium in all of your foliar sprays until harvest, and on Honeycrisp and other large-fruited varieties, you may want to make some specific trips just to get more Ca on.

Forwarding from Ollie Cultara at VT Agency of Agriculture, Food, and Markets- TB

Dear Vermont produce grower,

The Vermont Agency of Agriculture, Food & Markets seeks your input on improving outreach from the Vermont Produce Program (Agency of Agriculture produce safety program). Please complete this survey to share your opinions about the program and how we can better communicate with growers and consumers.

We are launching a statewide marketing campaign in July promoting local produce. The campaign ads will celebrate Vermont-grown fruits and vegetables and highlight farm food safety practices. Your responses to the survey will help us promote local produce and Vermont growers’ commitment to quality and safe growing practices.

The anonymous survey should take 5-10 minutes to complete. Take the survey here by July 1.

Thank you for your time during this busy season! Please be in touch if you have any questions.

Best,

Ollie Cultrara (they/them)

Produce Program Outreach & Education Coordinator

Vermont Agency of Agriculture, Food & Markets | 94 Harvest Lane, Williston, VT 05495

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A good question came up today regarding my recent recommendation on codling moth management: “Saw your note on Codling Moth and was wondering if Assail or Leverage or Belay would work as well as what you listed (Intrepid, Altacor, Belt, Rimon)?”

It’s helpful to have someone read your words back to you. The materials I mentioned are all pretty targeted, if not specific to, lepidopteran pests, and are all effective against codling moth. My unspoken statement was that if you are only targeting CM and want to use a ‘softer’ material, these fit the bill. But certainly, if you still have fresh curculio activity, or just have another material ready to go in the shed, a more broad-spectrum pesticide is fine to use. Assail, Delegate, Imidan, Voliam Flexi, and Danitol are other materials rated at high efficacy against CM in the New England Tree Fruit Management Guide. By all means, use them. Managing CM in high-pressure orchards is pretty critical now.

Take care. I’ll be out tomorrow morning with a tank of Intrepid and Calcium at the crack of dawn tomorrow morning. Were I in the commercial business, I might consider one last fungicide before calling it good for apple scab, but it’s important to get the fire blight I’ve seen out of the orchard and the 4-hour REI on Intrepid is pretty key to getting that done.

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 apologize for this overdue communication. Some grapes at the UVM Vineyard in South Burlington were starting bloom yesterday, and we are in peak disease management season. I’ll keep this brief:

1. Pretty much every major disease is likely active now, including black rot, Phomopsis, powdery and downy mildew, and anthracnose. Vines should be protected with the best materials in your toolbox. For non-organic growers, that means mancozeb or captan plus a DMI (FRAC code 3, e.g., Rally, Vintage, Inspire super) or strobilurin (FRAC code 11, e.g., Flint, Sovran, etc) material. Rotate those FRAC codes and do not use materials with the same code more than twice in a row.
2. For organic growers, this is the window to be using whatever copper material you choose.
3. Keep fungicide coverage on at 7-14 day intervals, shorter as there is more rain.
4. Keep an eye out for grape tumid gallmaker to be popping up. If these have been a problem in your vineyard, Movento or Assail are your best materials. I don’t know any organic option, so you’ll need to remove them by hand.
5. Shoot thinning is still critical now, the sooner it’s done, the more resources you will leave for the remaining shoots. Shoots have not lignified enough to do any combing.
6. If you suspect any nutrient deficiencies, this is a good time to collect petiole samples for analysis. I prefer the veraison timing, but bloom sampling allows for correction this season if somethings comes up particularly low. Details on petiole sampling can be found here.

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.

Category [tree fruit; IPM]

June 8, 2021

Sorry- I’m late on getting anything out, so I’ll cover the high points that are important for managing Vermont orchards in the next few days / week:

1. It’s time to get a codling moth spray on for many orchards. CM is best managed by using the NEWA degree-day model. For your site, enter the first pheromone trap capture (Biofix) or, with less certainty, let the model predict emergence (that’s the default). Most materials should be applied between 100 and 200 degree days (base 50°F) from that date. For most orchards, that is now. A lepidopteran-specific material like Intrepid, Altacor, Belt, or Rimon (latter two should have been on a few days ago) is best against this pest.
2. Plum curculio still has some activity left in it for this season in most orchards. If you covered the orchard with a relatively broad-spectrum insecticide at petal fall, border sprays will suffice to keep late-season damage down.
3. Apple scab primary season is done pretty much everywhere. Scout the orchard meticulously for signs of scab, if you have it, keep up a Captan program until things are burned out. Otherwise, fungal diseases are probably good for a little bit.
4. Fire blight- Streptomycin works!! We have tow partial rows at the UVM orchard with many dead trees that I plan to rip out (that’s another story), so I haven’t bothered spraying them this year. They are right in our Fire Blight-riddled cider block, which is 95-98% clean right now, but those Spitzenburgs are toast. Scout your orchard carefully for signs of the disease and plan to prune out ASAP, on a dry day. Except in the case of hail, do not apply streptomycin to an orchard that shows symptoms of the disease.
5. Fertility- If you’re applying nitrogen, start making plans to back off and shut it down soon. This is a great time to apply magnesium, potassium, and other cations if our soil or foliar analyses calls for them.
6. Every spray this time of year should include some calcium. On Honeycrisp, calcium should go on even if another spray material isn’t needed.
7. Keep an eye on thinning. This has been one of the most inconsistent years I have seen in my time with this crop (25 years) and I’m seeing and hearing of fruit densities all over the place. It’s getting late to apply thinners, so while scouting for Fire Blight, keep an eye out for trees that need a little hand thinning.
8. Water, if you can. Many areas of the sate are running dry, and we’re still in the window of maximum cell division that determines fruit size and quality.

All for now,

Terry

Vine growth is really ramping up in Vermont vineyards, which means that the next two months are critical to set the stage for a quality vintage for 2021. I often say that, once established, grapes are weeds, and I’ll stick to that assertion. However, there’s a difference between a plant that can grow profusely and managing it to provide optimal crop quality. It’s our jobs as farmers to manage the vines for our needs- that what makes us different from foragers of the wild grapes that indeed do grow like weeds all around us.

Top of mind right now should be two practices: shoot thinning and disease management. Shoot thinning is critical to channel the vine’s energy into an appropriate number of shoots to maintain vine balance, and to high quality shoots to ensure consistency of ripening. We typically target 4-6 shoots per foot of canopy. So, vines on six-foot spacing should have about 24-36 well-spaced shoots on them, assuming they have filled their space. Adjust that as needed- vigorous vines get more shoots, less vigorous ones fewer. Now, since they haven’t lignified, you can just pop them off with your fingers. Be sure to select the most consistent and healthy shoots to leave behind. On many cultivars, the secondary shoots, which will be behind in development and thus smaller than the primary shoots, may emerge from the same bud at the base of a more desirable shoot- break those off. Remember thought that breaking off shoots is likely to remove the basal buds that could form next year’s shoots, so you only want to break these off that are in a position where you do not want a renewal spur for next year. This is a great time to strip shoots off the trunk from the fruiting zone down to the trunk base, but leave a sucker or two at the bottom as a renewal option in case the trunk freezes out or is otherwise damaged. I explain this process in a video here (15 minutes, pardon the wind noise); my colleague at Cornell, Dr. Justine Vanden Heuvel, describes in more succinctly using Vinifera cultivars in slightly different training system here.

This is a typical time to start thinking about a spray program to manage disease. 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.

As a reminder, a refreshed version of the Initial IPM Strategy for New Cold Climate Winegrape Growers is available at: https://www.uvm.edu/~orchard/fruit/pubs/Factsheets/UVMFRT004_initialIPMStrategy.pdf

Organic growers are in for a bit more work. The standard fungicides, copper and sulfur, have only fair efficacy against this disease at best, and in a couple of weeks when black rot becomes the next disease of concern, those materials will have even less efficacy against that disease. The first line of defense in an organic vineyard is a strict sanitation program. This includes removing all mummies still in the canopy (not dropping on the ground, but actually removing them from the vineyard) as well as any obviously diseased wood. Phomopsis and anthracnose both overwinter largely on infected wood in the canopy, and removing this wood during dormant pruning or now is essential to reducing disease pressure. Stubs left at the ends of spurs should now be removed since you can see where this year’s shoot growth will resume (at the developing shoot)- these stubs will die and may become infected with phomopsis this season (or were last season) .

Removing stubs at end of retained spurs.

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.

Despite the rain we just received, most sites in Vermont are still running very dry. Established vines on most soils should be okay, but consider watering young vines. I’ll discuss soil fertility later this week.

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.

Virtual Honeycrisp Meetup – A three-part series of conversations about Honeycrisp Researchers, extension specialists and grower panelists; New York grower Rod Farrow; Michigan grower Chris Kropf and Washington grower Bruce Allen Join us and bring your experience and questions! Register to each date in the links below. JUNE 3rd CROP LOAD MANAGEMENT Register JUNE 17TH ROOTSTOCKS Register JULY 1ST NUTRIENT MANAGEMENT Register Facilitated by B. Sallato WSU Extension, M. Miranda Sazo Cornell Cooperative Extension, and A. Wallis MSU Extension. Supported by IFTA, USDA-SCRI Root2Fruit project and Good Fruit Grower. For more information visit http://treefruit.wsu.edu/event/virtual-honeycrisp-meetup/2021-06-03/

I want to get this one out quick:

(Cornell) Champlain Valley Virtual 10-12mm Thinning Meeting Today at 1PM

The Champlain Valley 10-12mm meeting will be held today from 1-2PM. At this meeting, Dr. Terence Robinson will discuss his thinning recommendations for the 10-12mm timing. To join, simply click on the link at 1PM. Join Zoom Meeting https://cornell.zoom.us/j/99544274591?pwd=NHZkZU1HK2ZmTDkvc2hCeHhCdW96QT09 Meeting ID: 995 4427 4591 Passcode: 288556 One tap mobile +16468769923,,99544274591# US (New York) +16465189805,,99544274591# US (New York)

On that note, here’s my quick rundown of things to in the orchard:

1. Manage plum curculio. This should be pest # 1 right now, and with hot, humid weather, its activity should be pretty high. PC is active from petal fall but especially at 8-12 mm fruit size, until 308 degree days (base 50°F) after petal fall. There is a model in NEWA, use it.
2. Codling moth is pest #2. If you monitored CM in pheromone traps and recorded first date of capture, use that in the NEWA model, or hand calculate degree days (also base 50°F). Sprays should be timed at 150 DD for ovicidal materials (Rimon, Intrepid, Esteem) or 250-360 DD for most other materials. As usual, use the New England Tree Fruit Management Guide to help guide selection.
3. Start adding calcium to sprays any time now, especially on Honeycrisp.
4. While we’re talking nutrients, trees are in their main flush of growth, so any nitrogen fertilizers you’ll be applying should be going on now.
5. Water! Things are really, really dry out there, and that’s not looking to change any time soon.
6. Because of that, apple scab is on the back burner, mostly. When we get rain, scab will be an issue. When you next spray, make sure you’re staying covered.
7. There are a lot of reports about powdery mildew showing in area, which does not require leaf wetness, only high humidity. For orchards with a history of PM and with susceptible cultivars (Cortland, Gala, Ginger Gold, Idared, Jonathan, Mutsu (Crispin), and Paulared), you may want to include a material with some efficacy against the disease. From the NETFMG: “The most common multi-site fungicides, captan and mancozeb, are ineffective against powdery mildew. DMI fungicides vary in effectiveness. Unfortunately, the DMIs most effective against powdery mildew, Rhyme, Rally, Rubigan and Procure, are least effective against scab, and vice-versa. QoI fungicides, Flint, Flint Extra and Sovran (and pre-mixes with Group 11 ingredients) have good efficacy against powdery mildew. SDHI fungicides, Aprovia, Fontelis and Sercadis (and pre-mixes with Group 7 ingredients) are somewhat less effective, but still provide good control. Low rates of sulfur are effective in low disease pressure environments, such as New England, but the risk of sulfur injury increases as temperatures go over 85°F. In organic production systems, sulfur applied at weekly intervals, and bicarbonate and peroxide-based fungicides applied on 3-5 days intervals are the best options. (TB note: in my 12+ years of growing apples organically using sulfur to manage scab, I never saw PM in orchards managed using that system.)
8. Keep an eye out for fire blight infections. If you find any, cut them out as soon as you do. But, please send me an email, as my colleague Dr. Kerik Cox at Cornell is tracking Erwinia amlovera (the causal bacteria of the disease) strains in the northeast and testing for streptomycin resistance.

Okay, that’s all for now. Who knows a good rain dance??