We have a video up on YouTube this week if folks want to see what’s going on in our orchard. -TB

We are settling into summer mode in Vermont orchards. For most of us, the weekly disease management treadmill is behind us, as all overwintering apple scab ascospores have long been released, so as long as we covered our orchards well and have no scab in the orchard, it will not spread for the season and we can check that one off the list. If you do have apple scab, and you should do a thorough scouting to see if you do, then you’ll need to keep a consistent 10-14 day coverage of protectant fungicide to prevent conidial infections from spreading. Some rust and powdery mildew have popped up here and there but are largely under control from sprays applied around the bloom and postbloom window. Diseases to keep an eye on include sooty blotch / flyspeck and the various summer rots; captan does a pretty good job on those and I like to add in a single-site material like a group 3, 7, or 11 in late June or early July if weather has been hot and humid to add some activity against the rots.

Plum curculio ovipositioning should be wrapped or soon wrapping up in all orchards but those I the coolest sites, as that pest is only active for 308 degree days base 50F after petal fall, so no more applications need be made for them. We are well-into scouting and management season—last week I mentioned that we were well-timed for a spray to target codling moth based on our first trap capture on 5/20 (an application was timed for 200 DDb50F after that), and we may make a second application in 10-14 days if trap captures remain at 5 or more moths per week.

We have just started catching obliquebanded leaf roller in baited pheromone traps. Many growers have been asking about other moths in their baited OBLR traps, as there are many other pests that can be attracted to them, particularly redbanded leafroller. We don’t tend to manage specifically for the latter pest, as managing for OBLR typically takes care of RBLR as well and the trapping and degree day model for OBLR is more accurate than for OBLR. For orchards with a history or consistent catches of OBLR, the first spray for managing them may be timed at 350 DDb43F after the first catch (and there’s a NEWA model for that). Finally, on the insect front, you may want to start scouting for mites, especially in historically problematic blocks or if you have backed off prebloom oil applications. Page 14 of this archived section of the 2015 New England Tree Fruit Management Guide has a good description of the protocols for mite sampling.

It’s getting late to be applying nitrogen fertilizers, so plan on wrapping those up soon. It’s not a bad idea to have calcium in every foliar spray this time of year.

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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/alebradshaw

UVM Commercial Horticulture | UVM Fruit Blog
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