Save the dates: Educational opportunities for the winter season

I have two ‘save the dates’ to get on your calendars for the 2025 winter meeting season:

  1. The Vermont Tree Fruit Growers Association / UVM Fruit Program 129th Annual meeting will be held at the American Legion in Middlebury, VT on Friday, February 21.
  2. The New England Extension Fruit Consortium will again offer a series of online webinars in February and March. Topics will include: Basic Orchard Weed ID and Management; Bitter Rot and Sunburn Management; Apple Scab- What Happened in 2024?!; Common Retail Marketing Mistakes (and how to not make them); and Tree Fruit Cold Hardiness Updates. The NEFC team is working hard to get speakers lined up and will be coordinating credits for the sessions that qualify. More details coming soon! Registration details may be found at: https://ag.umass.edu/fruit/news-events/northeast-extension-fruit-consortium

Have a happy holiday season and I look forward to seeing everyone soon,

Terry

__

Terence Bradshaw (he/him)
Associate Professor, Specialty Crops

Chair, Dept of Agriculture, Landscape, and Environment
(formerly Plant and Soil Science)
College of Agriculture and Life Sciences

University of Vermont
117/210 – Jeffords Hall | 63 Carrigan Dr
Burlington, VT 05405

(802) 922-2591 | tbradsha
https://go.uvm.edu/pssbradshaw

UVM Fruit Website | UVM Fruit Blog
Horticulture Research and Education Center
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Cornell ENY Soil Health and Mycorrhizal Fungi Meeting August 15

While this meeting is based around apples, the concepts apply just as much to vineyards, so I am sharing to both lists. -TB

Eastern NY Orchard Soil Health and

Beneficial Fungi Workshop

Northern Orchards Walker Farm

688 River Rd, Peru NY 12972

August 15, 2024 3-5pm

(Rain date: August 16 if needed)

The soils that we grow our trees in play a critical role in the success of our orchard’s productivity. Mycorrhizal fungi provide many benefits to the soils, though it is still unclear to what extent inoculating our soils with commercial blends of these fungi may have on the growth of trees during orchard establishment.

Join members of CCE ENYCHP, the Cornell Soil Health Program, and CCE Harvest NY for a field meeting on the basics of soil health, building climate resilient orchard soils, and an update on the current project status of our SARE grant on the potential benefits of inoculating orchards with mycorrhizal products.

This meeting is intended for farmworkers, young and beginning orchardists, and experienced orchard managers wanting to learn about the basics of soil health and mycorrhizal fungi within the orchard.

Agenda

3:00 PM – Welcome and Introductions

3:10 PM – The Basics of Orchard Soil Health with Dr. Debbie Aller

3:50 PM – Planning for Climate Resiliency In Orchard Soils with Dr. Kitty O’Neil

4:20 PM – The Basics of Soil Mycorrhizae in New York Apple Orchards with Mike Basedow

5:00 PM – Meeting Concludes

Cost: Free!

Registration: https://bit.ly/eny-soilhealth-beneficialfungi-2024

For more information, please contact Mike Basedow at mrb254 or 518-410-6823

__

Terence Bradshaw (he/him)
Associate Professor, Specialty Crops
Interim Chair

Dept of Agriculture, Landscape, and Environment
(formerly Plant and Soil Science)
College of Agriculture and Life Science

University of Vermont
117/210 – Jeffords Hall | 63 Carrigan Dr
Burlington, VT 05405

(802) 922-2591 | tbradsha
https://go.uvm.edu/pssbradshaw

UVM Fruit Website | UVM Fruit Blog
Horticulture Research and Education Center
Message me on Teams

UVM’s Our Common Ground Values:
Respect | Integrity | Innovation | Openness | Justice | Responsibility

UVM is subject to the Vermont Public Records Act and communications to and from this email address, including attachments, are subject to disclosure unless exempted under the Act or otherwise applicable law.

Midsummer orchard / vineyard management

I hope everyone is doing okay after the already wet season and this past week’s damaging rain event. Unfortunately, these events are too common, such that UVM Extension has a resource page ready to go: https://www.uvm.edu/extension/disaster-resources. I know that orchards and vineyards are generally on higher ground and thus likely saw less damage than the vegetable farms and hay/corn fields near the rivers, but if anyone needs anything, please reach out to me.

Given the similar state of affairs in orchards and vineyards- dealing with wetness (and disease), occasional insect management, weed management, and canopy management, I am combining apple and grape bulletins. For both crops, consider maintaining fungicide coverage in light of all the water we have been inundated with. For apples, that means keeping coverage on for fruit rots, grapes should be protected against downy and powdery mildews and botrytis before bunches close up. Insects of not should be apple maggot and codling moth in apples and grape berry moth in vineyards.

Midsummer is the time for plant tissue testing in apples and grapes. Apple leaf samples are usually collected between July 15 – Aug. 15. Grape petiole samples may be collected at bloom or veraison, and comparisons between years or blocks should be based on the same time of collection. Veraison samples are a couple of weeks out for most vineyards. Samples should be collected separately for each cultivar or block. For apples, collect 50 leaves from the middle of this years’ terminal growth- not too old nor too young- from throughout the block and the tree canopy. In each vineyard sample, a random collection of 75-100 petioles should be collected from throughout the planting. Petioles should be collected from the most recent fully expanded leaf on the shoot, not across from the fruit cluster as is collected for a bloom sample. Just remove the whole leaf and snip the petiole (the leaf ‘stem’) off with your pruners.

Gently wash each sample in water with a drop of dish detergent, then rinse fully and place in an open-top paper bag to dry. The best analytical lab for grape petiole analysis that will provide recommendation for next year’s nutrient inputs is Dairy One, which is associated with the Cornell Nutrient Analysis Laboratory. Video- Taking a Foliar Sample: Vineyards and Orchards Taking a Foliar Sample: Vineyards and Orchards (University of Minnesota)

The UVM Agriculture and Environmental Testing Lab can provide analysis, but at this time their output does not generate fertility recommendations. The following are potential options of labs for analysis. It is recommended that you contact the lab for instructions and costs before samples are sent. Plus, it is important to confirm that they will send recommendations along with the analysis.

  1. Dairy One: https://dairyone.com/services/forage-laboratory-services/plant-tissue-analysis/
  2. University of Maine Analytical Lab: http://anlab.umesci.maine.edu/
  3. Waypoint analytical: https://www.waypointanalytical.com/Agricultural

Stay safe out there and as always please reach out if you need anything.

Terry

__

Terence Bradshaw (he/him)
Associate Professor, Specialty Crops
Interim Chair

Dept of Agriculture, Landscape, and Environment
(formerly Plant and Soil Science)
College of Agriculture and Life Science

University of Vermont
117/210 – Jeffords Hall | 63 Carrigan Dr
Burlington, VT 05405

(802) 922-2591 | tbradsha
https://go.uvm.edu/pssbradshaw

UVM Fruit Website | UVM Fruit Blog
Horticulture Research and Education Center
Message me on Teams

UVM’s Our Common Ground Values:
Respect | Integrity | Innovation | Openness | Justice | Responsibility

UVM is subject to the Vermont Public Records Act and communications to and from this email address, including attachments, are subject to disclosure unless exempted under the Act or otherwise applicable law.

H.706 Neonicotinoid bill and impacts on Vermont apple and grape producers

Since the Vermont House of Representatives and Senate voted to override the Governor’s veto of H.706, An act relating to banning the use of neonicotinoid pesticides, I have received a number of questions about the bill’s impact on fruit growers. The answer is, not much.

The main focus of this bill is the phasing out of neonicotinoid seed treatments on corn and soy seeds. Neonicotinoid seed treatments are a class of pesticides that are applied to manage insect pests that feed on germinating crop seeds. Nearly all non-organic corn and soy seeds planted in Vermont, and in the U.S overall, are treated with these insecticides. The bill was passed in response to concerns that the seed coatings may either show up in insecticide residue in pollen and nectar of treated plants or nearby plants that took up the insecticide from surrounding soil or water runoff. Other routes for insecticide exposure into the environment include runoff of insecticide into waterways surrounding treated fields and dust generated during planting. This prohibited use, which goes in effect in 2029, will not directly affect fruit growers.

There are other prohibited uses of neonicotinoids in the bill. The first is a blanket ban on application of them during bloom. This piece of the legislation is a bit superfluous to the fruit industry. Under Vermont pesticide rules, pesticide applicators must notify beekeepers within 48 hours of all pesticides applied during bloom, and virtually all insecticides labels include a prohibition on applying them to flowering crops or even when flowering weeds are present. In separate surveys, apple growers have indicated that they follow this rule fastidiously- in a 2017 survey of Vermont apple growers, 100% reported not spraying insecticides before or during bloom and 82% reported not using pesticides rated highly toxic to bees on their farms; and in a 2023 survey, growers rated themselves an average of 8.5/10 for their efforts toward protecting bees and other pollinators on their farms. I have long advocated in my Extension recommendations for growers to not spray any insecticides during bloom, and in almost all cases, I have recommended not spraying insecticides prior to bloom. The industry has followed those recommendations to a tee.

Other prohibitions in the bill include a ban on outdoor uses of neonicotinoids to soybeans or cereal crops (e.g., foliar application to corn and soy after crop emergence); outdoor applications to certain vegetable crops; and applications to ornamental plants. Apples, which are not uncommonly sprayed with one or two applications of foliar-applied neonicotinoids per year, were spared by omission. I testified in the Senate agriculture committee in April about how the industry uses neonicotinoids and other insecticides and included information from grower reports of pollinator health in Vermont orchards. If the legislation has its intended effect of improving pollinator health, Vermont orchards should see more diverse and abundant pollinator populations in the future. That said, apple growers are already reporting strong wild pollinator populations on our farms, and a majority of farms are relying on wild pollinators for the critical pollination services we need to support our crops. We’re doing something right.

Grapes are a bit of a different story in a couple of ways. First, grapes are wind pollinated and thus are not dependent on insect-mediated pollination. That means that pollinator populations are lower in vineyards overall, except on blooming groundcovers. Second, insect management is a relatively minor component of Integrated Pest Management in Vermont vineyards, where disease management is the main concern. Grape berry moth is the main concern in many vineyards, and it is both not present at damaging levels on many farms and also easily manageable with ‘soft’ insecticides (e.g., Altacor, Intrepid, Delegate, Dipel, and other Bt products) with minimal impact on pollinators or other beneficial insects. Many Vermont vineyard never apply an insecticide in their annual IPM program.

I served as the Chair of the Vermont Pollinator Committee in 2016-0217 and have stayed abreast of all legislation and rulemaking around pollinators and pesticides in general since and even before then. As long as we continue to be the good stewards of the land that we have been, we should be good as far as this legislation is concerned. For all of us, and especially tree fruit growers, we walk a fine line of supporting wild and managed pollinators on our farms while also protecting our crops from insect and other pest damage that can quickly ruin a crop. I am glad that in 2024 we operate on a mature, advanced IPM system that balances these well. Keep up the good work.

Thanks,

Terry

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.

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. University of Vermont Extension, Burlington, Vermont. 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.

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.

Reminder: Monarch tractor demonstration tomorrow, June 20 (Shelburne only)

Representatives from Monarch Electric Tractor Company will be in Vermont on June 20 (tomorrow) to demonstrate their driver-optional MKV electric tractor at Shelburne Vineyard, 6308 Shelburne Road,

Shelburne, VT. Due to the expected heat conditions, we will be cancelling the afternoon demonstration that was to be held in Underhill. Please register to attend (for free) at:

Shelburne Vineyard 10am Vineyard Demo:

https://www.monarchtractor.com/shelburne-vt-demo

NRCS may offset the cost of electric tractors through their EQIP program, contact your local office if interested.

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.

Vermont Apple IPM- Summer pest management

Sorry about the delay in getting this out, graduating a kiddo from high school is more of an event than I’d planned. Anyway, there are a few orchard items I want to touch on. First and probably foremost, the heat we are expecting this coming week could provide substantial stress to trees, not to mention farmers and farm workers. Plan ahead and take care of yourselves. If you have irrigation, is should absolutely be running this week. Even with drip irrigation, well-watered trees will have cooler canopies due to increased transpiration and evaporation from leaves. High temperatures combined with many pesticides can lead to phytotoxicity ranging from minor leaf burn to fruit finish damage to tree defoliation- I’ve done them all. Pay attention to any warning on labels and do not spray during the heat wave. I’d say Sunday is your last day to apply anything this week before it gets too hot.

Heat stress on trees not only contributes to general tree decline, but also predisposes fruit to certain rots. I have visited some orchards and haven’t seen any apple scab, so most can step back from regular sprays for that disease. However, protection should still be applied to reduce fruit rots. Captan is the standard summer fungicide for its efficacy against the cosmetic diseases sooty blotch and flyspeck as well as against fruit rots, and is more effective when mixed with topsin, a strobilurin fungicide (FRAC code 11, e.g., Flint, Sovran, Merivon, Prostine, etc.), or a phosphite fungicide (e.g. Rampart, OxyPhos, Prophyt, etc.). Summer fungicides should be applied every 10-20 days depending on rain, and I find that most well-managed orchards that market direct to consumer and don’t store fruit for long with trees pruned and grass mowed to allow for good airflow can get by with 2-3 post-scab summer fungicides. That’s a lot of qualifiers, but it works for us and for many other farms. Farms that will store fruit or process on a packing line and thus have greater likelihood of disease development in storage and / or lower tolerance for cosmetic diseases may need to cover more, and would do best to follow the NEWA SBFS model.

Insect pests of note right now include the tail end of codling moth egg hatch and increasing obliquebanded leafroller activity , so a second application against them would be warranted in orchards that have a history of damage (most, by now) or trap capture over ~5 codling moths per week. A lepidopteran-specific material like Delegate, Intrepid, Altacor, Belt, Exirel (DON’T mix that one with captan) would best target those pests. Plum curculio should be done ovipositing in most all orchards. Now is the time to get started coating apple maggot fly traps to be hung shortly. 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. We will also be distributing some traps, but will need to do so on our (limited) drives as they don’t ship well when the adhesive has been applied.

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 (Gemplers, GL IPM) 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. Remember to rotate your insecticide chemistries to avoid resistance development in pest populations. Resistance isn’t a huge issue with apple maggot fly that has one generation per year, but codling moth and other lepidopteran pests are still about and subjecting successive generations of them to the same class of materials can induce resistance. 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.

I have seen one pretty bad case of European red mites already, and hot, dry weather is also conducive to mite flare-ups. A weekly or, if the numbers indicate, bi-weekly scouting will help to indicate if there are high enough mite numbers to consider treatment. Information on monitoring: https://netreefruit.org/apples/insects/mites. Mites should be treated based on the following thresholds: in June, 1-2 mites per leaf; July, 5 mites per leaf; in August, trees are more tolerant of feeding so treatment should only be applied if there are over 7.5 mites per leaf.

It’s time to wrap up any ground-applied nitrogen fertilizers, but potassium and magnesium fertilizers can be applied any time in summer. It’s also a good idea to start your regular foliar calcium sprays, especially on bitter pit-prone cultivars like Honeycrisp and Cortland.

That’s all for now. Stay cool out there this week- it’s a good time to do fieldwork ‘farmer’s hours’ in early morning (or ‘hobby farmer’s hours’ in the evening).

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.

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. University of Vermont Extension, Burlington, Vermont. 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.

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.

Monarch tractor demonstration June 20

Representatives from Monarch Electric Tractor Company will be in Vermont on June 20 to demonstrate their driver-optional MKV electric tractor in Shelburne and Underhill. Please register to attend (for free) at:

Shelburne Vineyard 10am Vineyard Demo:

https://www.monarchtractor.com/shelburne-vt-demo

Chamberlin Farms Vegetable / Field Crops 4pm Demo:

https://www.monarchtractor.com/underhill-vt-demo

This should be pretty exciting to see in-action.

V tWhere 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.

Weed Management Field Meetings in NY June 20 and 21

Passing this on from Mike Basedow at Cornell Cooperative Extension. -TB

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Weed Management Field Meetings

June 20: Hudson Valley

Mead’s Orchard

15 Scism Rd, Tivoli NY 12583

9am – 11:30am

Join us on the morning of June 20th as we hear from Cornell University weed management specialists Dr. Lynn Sosnoskie and Dr. Yu Jiang regarding their research updates, as well as ENYCHP’s Mike Basedow for updates on his herbicide trials, and NYSIPM’s Bryan Brown on site-selection and other non-herbicide options.

Identifying the differences between weed species and key differences between annuals and perennials that factor into management will also be covered.

DEC Credits have been applied for for this meeting.

Cost: Free!

Registration: https://bit.ly/3UDBcze

June 21: Champlain Valley

Northern Orchard Walker Block

688 River Road, Peru NY 12972

June 21, 2024 9am – 11:30am

Join the ENYCHP on the morning of June 21st as we hear from Dr. Lynn Sosnoskie and Dr. Yu Jiang about their recent research looking at autonomous orchard crop management and weeding technologies.

We will then visit three of Mike’s active herbicide research plots to see firsthand the level of control the trial treatments are providing during the critical weed free period.

2.50 DEC Credits are available for this meeting in categories 22, 1A, and 10.

Cost: Free!

Registration: http://bit.ly/3JZwarZ

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UVM Apple IPM: Fruit set, insect activity picking up

Now that we’re past petal fall and many have had a chance to assess the effects of any thinning sprays applied last week, it’s worth assessing the situation as we head into summer. I have not made many orchard visits yet this year but have seen a few, most of my observations are from our own UVM orchard in Sout Burlington. Fruit set and thinning are all over the map for us, but overall we have a bit more fruit than I like, and we’ll be pitting on a middle0rate 6-BA (Maxcel) application tomorrow before things warm up for the weekend. Other growers are reporting good thinning with some need for retreatment, and at least one has feared overthinning. Remember that as fruit get larger than 15 mm diameter they will be unresponsive to most thinners, so our window is closing. For those lucky enough to have peaches, now is the time to thin those, too. This is usually a manual job, but there is a new thinner, Accede, but it is rather late for it to be effective. Remember to refer to the New England Tree Fruit Management Guide for thinning and other spray recommendations.

Insect activity has been pretty low but picking up. Anyone trapping codling moth should have recorded your first date of capture, this sets your biofix for when to start accumulating degree days to time sprays for the first generation. In South Burlington, we caught our first moth on May 17, and from then until today we have recorded 229 degree days (DD, base 50°F) using the NEWA calculator. Eggs are just starting to hatch, and optimum timing for treatment with most materials is around 250 accumulated DD. We’ll be adding Delegate to tomorrow’s spray mix to catch those hatching larvae, as we expect to hit that threshold by Saturday. Plum curculio are still active for 308 DD after petal fall (which I am calling 5/21 for us), so I am adding a second Avaunt treatment to that spray tank tomorrow. I did see some fresh damage in border trees yesterday. The choice of two different relatively expensive insecticides is to cover the spread of pests that are active right now, and to get ahead of populations before they breed and subsequernt generations proliferate. Based on Dr. Jaime Piñero’s efficacy summaries, Avaunt is excellent against plum curculio but moderately effective against other insects, and Delegate is an excellent material for lepidopteran pests. We have not used organophosphates at the UVM orchard for many years, so do not use Imidan which could cover all of the insects of concern. Verdepryn or Voliam could be good choices, but I don’t have them in the spray shed.

Apple scab should be done in most orchards but we don’t know until we’ve done a thorough assessment after primary ascospore release is finished and any infections have had time to develop. I saw no scab yesterday, but we will be including captan as coverage for any potemtially developing infections and to provide protection against summer diseases and rots before we back off into our summer schedule.

If you’re applying nitrogen fertilizers, you have just a couple more weeks to get your last applications on before we start to compromise winter hardiness.

All for now, 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.

VT Apple IPM: Petal fall edition

Video from the orchard this week: https://youtu.be/P1K7XWlg35M

Champlain Valley and other warm site orchards are approaching full petal fall, so there are a lot of decisions to make in the days ahead. Hopefully everyone with any hint of risk for fire blight treated sometime late last week or over the weekend, orchards in bloom may consider treating given this heat spell that’s about to pop up. Everyone also needs to keep an eye out for blossom blight symptoms, and for the shoot blight that will follow. Growers can apply prohexdione calcium (UMASS factsheet, Apogee label, or Kudos label, 6-12 ounces per 100 gallons dilute**) any time now to reduce shoot blight incidence. The plant growth regulator does not affect the bacteria that causes fire blight, it only reduces susceptibility of shoots to infection by thickening cell walls. Treatments will reduce shoot elongation and thicken cell walls for about 2-4 weeks post-application, so retreatment may be necessary every 1-4 weeks until terminal bud set.

In light of the heat that we’re experiencing in the next couple of days, if you can avoid spraying anything (streptomycin excepted) when the weather is >85°, that’s a good thing. Then again, don’t ignore the very real threat of the following pests that need to be protected against.

We are approaching the end of apple scab season, but don’t relax just yet. NEWA is predicting that all spores are mature in warm sites and will all be released with the next decent rain, but the model can lag behind biology. I recommend maintaining coverage for the next couple of weeks. For cooler inland and upland sites, there are likely still spores remaining on the overwintering bank, so stay covered and consider using a kickback material from FRAC class 3,7,9, or 11 if you have any question about residue heading into an infection period which we may see mid-week. As far as materials, everyone should plan on phasing out mancozeb soon, as it it toxic to beneficial predatory mites that do some great biological control or European red mite and two-spotted spider mite, and we’ll soon have to be thinking about its 77-day preharvest interval. Organic growers, I would apply sulfur before and after the rain event, and maybe consider lime sulfur (LS) for the second spray to provide some post-infection control. LS is caustic, nasty stuff, so use it wisely, wear all the appropriate gear, and wash everything down well as it is very corrosive to steel and other materials.

If you’re at total petal fall, then it’s time to start thinking about insect pests, especially plum curculio (PC). PC love this heat and will be ready to oviposit on fruit as they reach 7-10 mm diameter. Organic growers should plan on getting a coating or Surround on trees ASAP, and maintaining that coverage for about 400 degree days (base 50°F) after petal fall (NEWA has a good model for this). This is a longer window of coverage than for non-organic orchard management (308 dd base 50°F), because Surround does not kill the insects and so must be maintained longer until the biological urge to oviposit has completely subsided. For non-organic orchards, effective materials include Imidan, Actara, Avaunt, Voliam, and Agri-Flex. Carbaryl, if used for thinning (see below), will have some efficacy, but probably shouldn’t be your primary material of choice given the weather that is very conducive to PC activity. Thinning rates of carbaryl are about half the insecticide rate, and I would plan on using just that lower rate as a thinner and use a separate material for my insect management. Any of these materials will help to manage the other petal fall insects, including European apple sawfly and the various lepidopterans (obliquebanded leafroller, Oriental fruit moth, codling moth, etc.) that may be emerging at this time.

Thinning. Okay, this is always a tricky one. First, anything applied in the next 40 hours will be highly active because of the heat, so I’d err on lower rates and a lighter touch. A second application may be needed after this weather breaks. Now, I haven’t been in orchards all across the state, but where I have seen bloom from Connecticut valley, Addison county, and our own orchard in South Burlington, it was good to downright heavy. Pollination and fertilization conditions have been good, so I’d expect trees to need a decent thinning this year. The wild card is how much damage orchards may have seen from the April 25 freeze when many trees were at tight cluster bud stage. We are seeing some damage at the UVM orchard, but there are enough good fruit that are starting to set that I am ready to thin moderately aggressively this season. The New England Tree Fruit Management Guide has some good variety-by-variety recommendations, so I recommend starting there. A good, standard petal fall spray of 1 qt/acre of carbaryl and 8 oz/acre Fruitone N or L (I did the TRV adjustment for you) should do the trick for most orchards. As fruit approach 8-10 mm in size and the weather starts to warm up, the 6-BA thinners will be very active, and they are a great choice for small fruited cultivars (Macoun, Gala, Fuji, Empire). For organic orchards, it’s time to start hand thinning. A lime sulfur spray used for scab can help to knock some fruit off, but it’s not labeled specifically for that use.

I think that covers it for now.

**This reference to amount per 100 gallons dilute refers to Tree Row Volume (TRV), which is a somewhat out-of-vogue method for adjusting spray rates to compensate for canopy volume. I describe it some here, but in simple terms, it calls for measuring the tree canopy volume and estimating the number of gallons of water to saturate the canopy to wetness (dilute gallons per acre, DGA). No one sprays at full dilute, that wastes time, money, and water. For a good rule of thumb, large, standard trees 20 feet tall planted at 30 feet x 40 feet spacing had (notice the past tense) about 420 DGA. A more typical ‘large’ semidwarf orchard on M.7 or similar with 12 foot tall trees planted at 12 ft x 18 ft would have 200 DGA. DGA decreases down to around 100 and stays there pretty consistently for tall spindle and similar high density, narrow-canopy systems. BUT, we often do not recommend reducing TRV below 150, maybe 120 if you have excellent coverage and an easily sprayed canopy. And this TRV is only used to determine the rate of material used per acre, not how much water you put in the tank. So. Let’s just say use 200 DGA for semidwarf trees, 150 for trellised trees. Back to the Apogee example, let’s use 8 ounces per 100 DGA for simplicity’s sake, that would be 16 ounces per acre to the big trees, 12 ounces to the smaller high density trees. Then figure out how much to put in the tank based on the amount of water you spray per acre, which is likely 50 (or less?) to 150 gallons.

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