Scouting workshop May 16; apple season is well underway

By Terence Bradshaw

At the UVM Horticulture Research and Education Center (HREC), we hit the green tip bud stage on McIntosh today. This means that, even for orchards with relatively low apple scab inoculum that carried over from last year, disease management should commence any time. Today would have been a great time to put a protectant material on ahead of the rains expected tomorrow and through the weekend. For growers who had scab last year and who are at this same or later stage of bud development who did not have a protectant applied on Monday or Tuesday this past week, plan on applying a material with some kick-back action when the rain and winds die down. Scala, and Vangard are natural options at this time, as they work better in cool weather and have relatively little effect on fruit scab so they are less useful later in the season. For those who still use or planned to use it as a spring fungicide, Syllit/Dodine is no longer registered for use in Vermont, although remaining stocks may be used up. For orchards past 1/4” green tip, it is too late to apply copper fungicides at traditional labeled rates for efficacy against apple scab without risking fruit russeting. As always, check the New England Tree Fruit Management Guide for complete recommendations (hard copy guides still available at: http://go.uvm.edu/netfmghc).

On the arthropod front, this is still a good time to apply oil for management of mites, and Esteem may be applied against San Jose (SJS) and other scale insects if they are a problem in your orchard. Notice I did not recommend Lorsban (chlorpyrifos) against SJS and other insects at this time. That’s because chlorpyrifos products are no longer registered for use in Vermont.

This is a great time to start your orchard monitoring program: keep track of phenology on all cultivars are bud emerge and develop, and start hanging traps in the orchard for weekly (at a minimum) monitoring. Insect activity is generally pretty quiet now, but tarnished plant bug will start to move as days warm up. This would be a good week to get traps up for this insect pest. We recommend four white sticky traps per block hung knee high in a visible location, often at the block edges. Traps should be checked at least weekly and treatment for TPB considered if over threshold. Thresholds are variable based on tolerance for cosmetic damage- for apples marketed wholesale, three bugs per trap before tight cluster or five before pink bud would warrant treatment; for retail and pick-your-own orchards, the recommended treatment threshold is five and eight bugs per trap, respectively, for those bud stages. TPB and other insects managed at pink are usually treated with a synthetic pyrethroid material and that is still the recommendation. In order to conserve wild pollinators, we do not recommend use of neonicotinoid insecticides before petal fall.

On the subject of scouting, we will be hosting an Orchard Scouting Field Workshop at the UVM HREC on May 16, 1-4 PM to help growers with implementing scouting programs and to discuss upcoming management strategies.

Good luck out there.

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