By Terence Bradshaw

Things are a bit quiet in the orchards right now. Primary scab season is done, and there is little of it in commercial orchards where dry conditions and easy spray windows have allowed for decent disease management conditions. Fire blight- a minor annoyance in some orchards and absent in most, but keep an eye out for an errant strike here and there. Sooty blotch and flyspeck- these diseases require an accumulated 270 hours of leaf wetness to incubate between infection (e.g., a wetting event post-bloom in which you had no fungicide protection going in) and disease symptoms. We’re only halfway there, even if you had no fungicide coverage after bloom. That does mean, however, that summer fungicide protection may be needed in the next couple of weeks to manage these cosmetic diseases as well as the worse fruit rots (black, white, and bitter). See the New England Tree Fruit Management Guide for recommended materials, but generally, strobilurins, SDHIs, captan, and topsin are among those recommended. For organic growers, an application of a low-dose copper like Cueva or Badge may reduce fruit rots based on some preliminary work I did a few years ago, but watch your rates and don’t spray under slow drying conditions as fruit finish (russeting and lenticel blackening) may suffer. Maintaining trees via pruning, training, and appropriate rootstock/scion combinations to begin with can help to keep the canopy open to facilitate drying and reduce disease substantially.

Insects are relatively quiet. Mites (not an insect, but close enough for this sake) are nearly non-existent, even in a few of the hot spots I’ve seen over the years. Codling moth (CM) flight and egg hatch is still happening, and the timing for managing hatching larvae is now, either for your first or second spray for this generation. We’ve been trapping CM in every orchard we’re in this year, and while there’s no set threshold for when to spray, the general rule of thumb is that 5 or so moths per week in a pheromone trap is a light population, and more than ten indicates a larger problem. Where orchards are on the latter end of that spectrum, I recommend a second application during the first generation. Dr. Art Agnello at Cornell is recommending IRAC Group 28 (containing a diamide; i.e., Altacor, Exirel, Minecto Pro, Voliam Flexi or Voliam Xpress/Besiege) or Group 5 (spinetoram or spinosad) insecticides as the best options. For resistance management, it is best to use one IRAC class for the first generation, even if in two successive sprays, then switch to another class for the second generation.

Obliquebanded leaf roller still need some time to develop; I would plan to manage them along with apple maggot fly (AMF) or second-generation CM. Speaking of AMF, now is the time to hang red sticky traps in the orchard to monitor their populations. Baited traps placed four per block at the outside rows (to catch in-migrating flies) and checked regularly would indicate a population that needs management when a cumulative total of five flies is caught; unbaited traps are less effective at catching flies so an average of one fly caught per trap would indicate a need for treatment. We typically hit threshold at the UVM orchard in mid-July, but flies will start emerging from their pupae in the soil any day now. That also highlights an important management practice for this pest- removal or chopping (via flail mower) of dropped fruit to prevent pupation. Traps can be found at Gemplers and Great Lakes IPM.

On another note, for anyone looking for stimulating discussion this week, I’ll be part of a public panel with a number of my colleagues discussing Farming Practices and Ideologies this Tuesday at the UVM Davis Center. Information can be found at: https://www.facebook.com/events/187470125292645/. There is no fee for admission and we expect a lively discussion amongst the panel and the audience, so I encourage the Vermont orchard community to participate and weigh in. I’ll include specific information on the panel in another posting.

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, a USDA NIFA E-IPM

Grant, and USDA Risk Management Agency Funds.

By Terence Bradshaw

I’m not sure if everyone reads all the way to the bottom of my postings, or if things are going fine in Vermont orchards. If you recall, I was away working with apple growers and aspiring cider makers in Lebanon May 26-June 10, and was mostly unreachable. That I heard very little from growers suggests that either things are pretty quiet or I’m not needed. I’ll assume the former. I’ll also plan on presenting a trip report at the winter VT Tree Fruit Growers Association meeting, There are quite a few lessons we can learn from where the Lebanese apple industry id now, compared to our own situation now and especially over the past several decades. Stay tuned.

This week I’ve been getting caught up at the farm, in class, and with some upcoming research reports. Orchards are generally looking good. Primary apple scab is done, and if you missed infection periods, you’ll see lesions now. If you have scab in the orchard, keep covered with captan (sulfur if organic) and watch for lesions to burn out during hot/dry periods. It’s been dry and looks to stay that way (mostly) outside of rain expected on Monday. The next diseases to think about, assuming you have scab under control, are the summer tots and sooty blotch/flyspeck. Those all need substantially more moisture than we have had or are expecting, so sit tight. You can hold off on the fungicides for a while.

Monday I saw one single fire blight strike. That is important for two reasons. First, it confirms the predictions in Maryblyt that infections from the infection periods that may have occurred around May 25. Second, this strike was found in a Crimson Gold tree in our organic block. We do not use antibiotics in that block, and have suffered from substantial infections in most years. That we found one strike, and none on our most sensitive cultivar, tells me that that infection period was indeed relatively weak. Keep an eye out for strikes in your orchards and prune out when you see them, but I’d say we’re generally done worrying about fire blight for 2018.

Insects are another matter of course. Plum curculio (PC) are largely done in most orchards except inland/upland cooler sites- keep an eye on developing fruitlets for fresh damage and treat if needed. Perimeter sprays should be sufficient there. Codling moths (CM) are active and the eggs from the first flights are hatching. If you have had issues with this pest in your orchard, we’re in a good window to manage them. A broad-spectrum material could manage both CM and PC, but if you’re only concerned about the former, consider using one of the softer, lepidopteran specific materials like granulosis virus (e.g., Cyd-X) or an insect growth regulator (e.g., Rimon, Esteem, Intrepid) which are much safer on beneficial insects. Esteem is also effective against San Jose scale which are susceptible now if you’ve had a problem with those insects recently.

Obliquebanded leafrollers are just starting to fly now, there are a couple of weeks before we need to worry about them. As the weather turns hot and dry (trust me, it’s coming), keep an eye out for mites. Ideally, newer ‘soft’ IPM programs will help to maintain mite predator populations such that pest mites don’t require treatment beyond spring oil application.

Horticulturally, think about getting on any last nitrogen fertilizers before it gets too late and risks reducing cold hardiness. Where needed, magnesium and potassium may be ground-applied. Make sure to keep training new trees. As for thinning, the window to chemically thin has mostly closed. That said, if you still have too many fruit set, rescue thinning with Ethephon is an option that may be used cautiously.

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, a USDA NIFA E-IPM

Grant, and USDA Risk Management Agency Funds.