By Terence Bradshaw

Many growers, especially of pick-your-own or retail-sold fruit, are starting to think about wrapping up the pest management season for 2017. Before doing so, it is important to consider late-season insect and disease pests that could affect the crop going into harvest.

Apple maggot numbers ticked up in a lot of orchards last week so most sites that have a problem with that pest have reached the threshold for treatment. AM is relatively easy to manage and there are many materials labeled for doing so- Assail is probably the most commonly-used one, as well as Delegate or Altacor (good if you also have problems with lepidopteran pests), or Avaunt. Pyrethroids are also quite effective against this pest, but they are harsh on beneficial predatory mite species and thus their use after pink bud stage can cause flareups of mites and other secondary pests. Imidan is another old-guard material in the organophosphate class, but its use has been substantially restricted, and as a whole, we are encouraging growers to move past it. Organic growers can use a trapout strategy which would need to have been in place already to be effective; in lieu of that, carefully-timed application of spinosad (Entrust) or pyganic may be effective, although the latter breaks down very quickly in sunlight and thus cannot be counted on for any residual control.

We remain between generations for codling moth in most orchards. It would be best to keep an eye on NEWA for timing the management of the second generation. Application of a material effective against hatching eggs and young instar larvae is best applied at 250 degree days after moths begin flight, which is right about now. That would put us at about the first week of August to treat in warmer production areas of Vermont.

Mites are mostly a non-concern around the state except in certain problem areas, especially where pyrethroid insecticides are used to manage other pests. Scouting is the best way to determine need for treatment at this stage, and should be performed regularly and using the Cornell sequential mite sampling guidelines (here, page 15) as a reference.

Summer diseases-sooty blotch/flyspeck, late-season apple scab (if you didn’t control it in the spring), and rots (particularly black rot in Honeycrisp) are of particular concern, given the wet weather that has continued this season. Maintaining fungicides on a 14-20 day schedule should be the minimum.

Calcium will be important to maintain fruit quality and to reduce bitter pit; it should be in every tank that you’re spraying, especially for large-fruit cultivars.

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

July 9, 2017

As we move into midsummer, the busy hive of early season pest management is largely behind us, and we just need to keep a few things in mind. On the disease front, sooty blotch and flyspeck have the potential to be a big problem this year, so fungicide coverage should be maintained against those diseases. Use the NEWA model to guide applications, and know that two inches of rain are needed to remove previous spray coverage. These are purely cosmetic diseases (but in bad years the cosmetics are well-beyond consumer acceptance) , so fruit that is definitely destined for cider does not need management for them. Fruit rots may be an issue, especially if some hot weather rolls in. Keep a close eye especially on Honeycrisp, that cultivar may need a specific black rot treatment. I hope scab is under decent management, but where it snuck through, I’m afraid you’re still in the 7-10 day fungicide mode until after terminal shoot buds set. Continue to keep an eye out for fire blight strikes and cut out immediately.

As for insects, apple maggot (AM) is the main one we’re keeping an eye on. If you are planning to use them, red sticky spheres should have been deployed by now to monitor populations and flight to determine the need to treat. One Addison county orchard has already reached treatment threshold, and I expect others to need treatment in the next couple of weeks. But AM isn’t a problem in every orchard, so prophylactic spraying isn’t ideal. Codling moth (CM) has begun its second flight in most orchards, and eggs will be laid and will be hatching in coming weeks, there is no need to manage now. Mites may be a problem in some orchards, I have seen one block which was over threshold for two-spotted spider mites and required treatment already.

All sprays at this time of year, especially on Honeycrisp and Cortland, should include calcium in them, and applications of Ca may actually drive the spray schedule on those cultivars. Otherwise, keep mowing to improve air movement and reduce disease pressure in the orchard, walk those rows regularly (since you aren’t driving them as much with a sprayer), and keep note of the now incidental pests that are thankfully less common but easily missed, compared to those we all know are in our orchards in spring through fruit set.

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.