Vermont orchards are generally at green tip bud stage for the coolest locations in the state to tight cluster in warmer locations. Apple scab continues to be the primary pest management consideration of concern. I recommend maintaining a protectant fungicide and, given the off and on wetting of the last few days that has likely resulted in an extended infection period for most orchards, a single site fungicide with kickback activity such as those in FRCAC codes 3, 7, 9, or 11 (remember to rotate these chemistries to avoid development of fungicide resistance). Weather for spraying conditions has been all over the place this week with high winds on many days. It seems the best time for extended low wind conditions appears to be Wednesday night through Thursday morning. We are expecting, fairly substantial rainfall on Friday, which should result in the next major infection period.

As we approach bloom, it is important to consider the potential for the development of fire blight. I recommend having one application of streptomycin on hand as we head inro the bloom period. Streptomycin is always best used in conjunction with a degree day based fire blight model. Strep is extremely effective against blossom light infections when applied within 24 hours of infection and where bacteria has not developed resistance to it (and I have not yet seen evidence of strep resistant bacteria in Vermont.) There are other measures that may be taken to reduce reliance on streptomycin or increase its efficacy. Some biological control materials, (e.g., Lifegard, Actigard, Regalia) are labeled as an act as systemic acquired resistance promoters. These materials act like a sort of vaccine that prompts the tree’s immune system to fight off fungal and bacterial infections after application. While the data do not show complete efficacy against devastating diseases like fire blight, recent work (1, 2) done in New York State by Kerik Cox and Anna Wallis shows that they have potential to control blossom and shoot light at levels between a non-treated control and a streptomycin application. Where you may have had fire blight problems in the past, the use of one of these materials prior to bloom (as in this week) may help to reduce disease incident if infection occurs. Unless you are under constraints as an organic grower, I still recommend using streptomycin if the models call for it in your orchard. However, for growers, who have faced substantial fireplace problems in the past, the use of these materials may be affective in helping to get the disease under control in this in future season. The evidence is also good for the efficacy of low-rate(3 oz/acre) prohexadione-calcium (e.g., Apogee, Kudos) applied at pink bud stage followed by four biweekly applications at 2 oz/acre in reducing shoot blight symptoms.

Now is the time to get pheromone baited traps up for monitoring lepidopteran (moth) pests. The one that we monitor for most closely and which most likely drives management decisions is codling moth. Pheromone baited traps should be hung one per acre block and should be located 50 feet or more from each other to reduce the attractive effects from one trap to another. Pheromone capsules are specific to the type of moth that you were trying to catch, so each trap should include only one capsule for only one particular moth. For codling moth, we hang traps prior to bloom and check them daily, especially during warm weather, and record the date of first moth capture. I posted a video to our YouTube channel of me assembling and hanging a CM trap yesterday. That date can be used in the NEWA degree day model to time spray application toward freshly laid eggs or hatching larva. It is this precision of timing and maximizing efficiency of pest control materials that allows growers to use relatively expensive, highly selective (not harmful to most beneficial insects), and worker safe materials in a cost-effective manner. This year at the UVM orchard we are using pheromone traps for codling moth, obliquebanded leafroller, dogwood borer, and oriental fruit moth.

Growers should also be checking European apple sawfly traps that were hung last week and making counts of trapped insects. In some years, EAS may require treatment prior to bloom. We try to avoid the use of any insecticides at this point in the year because wild pollinator populations are increasing and we want to reduce the likelihood of residues that wild and managed honeybee pollinators are exposed to when visiting flowers during bloom. High levels of sawfly could cause substantial fruit damage, especially when bloom, when we are prohibited from using any insecticides, is extended. In the unlikely event that a pre-Bloom insecticide is used, I recommend, a relatively short-lived material such as a pyrethroid, and do not at all recommend the use of neonicotinoid material which have a high likelihood of having toxic residues in pollen and nectar that are collected by pollinators during bloom.

It’s time to really think about getting your nitrogen and other fertilizers on as the trees will be rapidly developing tissues in the coming weeks. If you are using granular fertilizers, I recommend split applications and applying half pre-bloom and the other half in early to mid-June, being sure to complete all nitrogen applications before the end of June to reduce likelihood of winter injury in the following season. If you have not yet it is a good idea to apply boron and zinc foliar fertilizers to strengthen developing blossoms prior to bloom.

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.

The recent warm weather has advanced apple bud stages significantly — we are at the half-inch green stage at UVM HREC and continued warm weather should keep things moving. I recorded a video at the orchard yesterday showing the bud development at the farm and discussing the need for disease management this week. Thankfully, there is no cold weather in the ten-day forecast, but there looks to be a pretty good rain / wetting event starting intermittently on Thursday but really getting going Friday afternoon and through Saturday. Wind conditions look decent to good in the next few days, so growers should consider getting a protectant fungicide on as soon as reasonably possible. For inland and upland sires that have slower bud development and may still be at green or even silver tip, this may be a good time to put on your copper, for orchards in warmer sites, a more typical protectant is in order. If you can’t get in until after a few showers have already started wetting things, an early-season application of a material with some postinfection activity may help prevent infection from developing. We are planning to treat the UVM orchard Friday morning with a combination of mancozeb and Vangard, the latter of which works better in relatively cooler weather and is not effective against fruit scab, and is therefore best used prebloom. Vangard has a FRAC code

of 9, which places it in the Anilino-Pyrimidine class of fungicides. These are not much used at other times in the season, and thus are easily rotated with other chemistries (i.e., materials with a different FRAC number) as we make our way through scab season. The New England Tree Fruit Management Guide includes a good list of recommendations for reducing the development of fungicide resistance in your orchard:

• Use a sanitation program to reduce inoculum.

• Use a multi-site fungicide in every spray – FRAC groups M3 and M4 – captan, mancozeb or metiram.

• Change site-specific fungicides – FRAC groups 3, 7, 9 and 11.

• Use at least three active ingredients from three different FRAC groups over primary scab season.

• If possible, do not use any one class of single-site fungicide more than twice in a season. For many fungicides, labels limit applications to no more than 4 per season.

• Whenever possible fungicides should be applied preventatively, before infection periods. Labels may suggest post-infection uses, but these should be used only as a last resort.

• Apply the maximum label rate of single-site fungicides.

• Pre-mix fungicides containing two single-site ingredients – Merivon, Luna Sensation and Luna Tranquility – should still be mixed with a multi-site fungicide.

• Each ingredient in a pre-mix fungicide counts as an application. For example, Luna Sensation with both fluopyram (FRAC group 7) and trifloxystrobin (FRAC group 11) would count as an application of a Group 7 and an application of a Group 11.

For growers who manage tarnished plant bug in their orchards, white sticky traps should be up in your orchard now. We posted a video last year showing trap setup and placement. The next traps to go up should be European apple sawfly, using those same white traps hung at head height just a bit before pink bud stage. A basic apple scouting guide can be found here. It’s a large format 11×17 pdf file, but also prints fine on 8.5×11 paper.

Now (half-inch green through pink bud stage) is a good time to think about applying a foliar nutrient tonic to help developing buds as bloom approaches. A combination of nitrogen, boron, and zinc is recommended and will help improve fruit set.

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.

Join the University of Vermont Extension and Vermont Tree Fruit Grower’s Association at these hands-on field meetings at Yates Family Orchard in Monkton on May 8th and Wellwood Orchard in Springfield on May 9th from 4:30-6 p.m. We will discuss commercial tree fruit management practices, value added products, marketing, pest and disease updates, pollinators, and funding opportunities and challenges. This event is free and geared to commercial growers and people that work with them. Please see attached for more information. Light snacks will be provided.

Each meeting has been approved for 1 VT Pesticide recertification training credit for categories 1A, 1, 2, 3, 4, 5, and 6.

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.

2025-spring-tree-fruit-twilight-meeting (003).pdf

I am trying out some 21st-century technology this week. First, I dictated my message while on my commute (with light editing), so the ‘writing’ style and length may be a bit different than folks are used to. Second, I recorded an update from the UVM orchard and placed on our YouTube channel. I intend to get one of those out on a fairly regular basis. Feedback is always welcome.-TB

Green tip bud stage was reached on McIntosh apples at the UVM Horticulture Research and Education Center in South Burlington today. This means that the active management season for apples has begun at our farm and likely has on many other farms around the area. Most farms in lower elevation warmer sites will see green tip by the end of the week; many upland sites may see it a bit after that. This stage is important because it signifies that there is susceptible tissue that can be affected by apple scab fungus. The fungus that causes apple scab and the apple tree co-evolved such that their early season lifecycles are very much in sync. The degree day model that we use to predict ascospore maturity and release starts at green tip on McIntosh and continues for roughly 900 degree days (base 32°F) after that. After this amount of accumulation has been reached, assuming normal conditions in the northeast regarding rainfall and humidity, we can assume that the overwintering inoculum for the apple scab disease has matured and will be released in rainfalls that occur during that period.

Under older conditions, growers were encouraged to maintain protective fungicide coverage from green tip through the end of ascospore release which commonly occurred around early to mid-June. However, a number of things have changed. The ability to closely monitor ascospore development and infection conditions using models such as those in the NEWA system allows us to better time our fungicide applications and reduce unnecessary, prophylactic treatments. We also have seen the bacterial disease fire blight increase in incidence in New England in the past 20 years. Fire blight can be considered essentially ubiquitous in the environment at this point, although it does not always reach infective potential many orchards. One of the key management techniques targeted toward fire blight is a delayed dormant application of a copper-based fungicide, which helps to reduce inoculum on the surface of plant tissues. This treatment, while technically still a chemical, is a relatively weak apple scab fungicide. However, the typically lower levels of mature ascospores, low amount of susceptible tissue exposed in the early season, and relatively cool temperatures experienced in early spring have typically lead growers to utilize this first fire blight management spray as their initial apple scab fungicide. If scab was relatively well-managed in your orchard last year, an application of a copper fungicide at full label rates should be sufficient to manage the disease for the next 7-10 days as long as it is applied before one quarter inch of green tissue is showing when looking at fruit buds from the side. That means there should be no leaves exposed from the emerging buds. Application of copper too late in the bud development can cause significant fruit russeting that can reduce the market value of your crop. This is an ideal week to treat orchard in the warmer production areas in the states with copper.

I have recently observed high levels of mites or scale insects in many orchards and how much of this due to reduction in the use of dormant or delayed dormant oil applications. While treating your trees with copper fungicide, it would be a good idea to include horticultural oil at a rate of 2% by solution (2 gallons in 100 gallons of actual spray material applied to the trees). Oil should be applied with very thorough coverage; I recommend 100 gallons of water per acre to fully saturate the trees. Oil works by physically smothering eggs and developing overwintering scale insects and therefore must thoroughly cover them to have affect. Oil should not be applied to orchards within 48 hours before or after a freeze event. Again, weather this week is conducive to oil application for most of the stakes, as we are not seeing significant risk of frost or freeze for the rest of the week.

Things tend to be pretty quiet on the insect front in this early season. Some growers may choose to hang white sticky cards at knee height in their orchard at about four traps per 10 acre block to monitor for tarnished plant bug. However, the vast majority of orchards in Vermont sell their fruit as pick-your-own or direct farmstand sales, and in my opinion TPB damage is insignificant and strictly cosmetic that should not need management for those that sell through those direct markets. For other farms that sell to wholesale markets, TPB can significantly reduce fruit quality that could lead to rejected fruit, so it may be managed on those farms. I recommend hanging TPB traps after the application of any copper fungicides in order to reduce the amount of spray that could make it difficult to read traps or make them less attractive to the insect. Pre-Bloom insecticide application for TBP may be warranted if there are more than three bugs per trap trapped in any given week. In order to reduce the likelihood of residues toxic to pollinators in apple pollen, I do not recommend the use of neonicotinoid insecticides (IRAC group 4A) prior to bloom. That leaves pyrethroid insecticides as the primary class that is typically used to manage TPB and other pre-bloom insects.

This is the perfect time to be preparing your soil and planting trees. When trees are planted in spring, growth in the first year is significantly better if planted during cool weather when roots are allowed to get established in soil before there is significant leaf and shoot development and therefore water and nutrient demand from the top of the tree. Ideally, apple trees should be planted by May 15, and certainly by the middle of June. For all new trees, whether on dwarf or semidwarf rootstock, irrigation should be immediately applied even if only only as a good thorough soaking from the water tank.

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.

I think burying my call for folks interested in receiving traps for orchard monitoring at the bottom of my first email last week left it unseen, so I’m resending on its own.

Scouting season is almost here in Vermont orchards. We have some funds available to distribute traps to growers around the state to help track pest incidence and better guide our recommendations to growers. If you are interested in contributing to the scouting program, fill out this interest form at here: https://forms.office.com/r/7QRfXfHqsd

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.

Good morning:

The growing season just keeps getting closer, I am calling today as the start of silver tip in McIntosh trees at the UVM Horticulture Research and Education Center. That means that the need for regular pest management is right on our doorstep.

For decades, the UMASS Fruit IPM program published the ‘March Message’ under the direction of the late Dr. Ron Prokopy. Since Dr. Jaime Piñero returned to the program in 2019, he has revived that old tradition. The Message contains a succinct and science-based summary of research, recommendations, and considerations to help growers navigate the year to come. It’s an excellent resource and I highly recommend reading it here: 33rd Annual March Message. Big thanks to the UMASS Extension Fruit Program for their work on this and allowing it to be distributed.

-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.