Orchard pest management, late July

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.

Midsummer orchard management

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.

Midsummer vineyard management

By Terence Bradshaw

July 9, 2017

Now that the July 4 holiday is past us, it’s time to really think about getting quality into those grapes on the vines. That doesn’t mean that the work that has gone into the 2017 crop hasn’t yet affected quality: the pruning, shoot adjustment, pest management, and other activities that are needed to keep a vineyard in good shape. But the next two months may be the most important in terms of developing high-quality fruit in this (so far) challenging year.

Pest management should continue to focus primarily on disease management. It has been a difficult year so far with all of the rain, and the frequency of it, to maintain fungicide coverage but I have been seeing mostly clean fruit and foliage in vineyards which have maintained an appropriate spray schedule of 4-5 well-selected and –timed fungicides since prebloom. At this point, phomopsis is pretty much done, and black rot will soon be winding down. Powdery and downy mildews (PM?DM) should be the main focus for disease management, as well as botrytis a few weeks down the road. If this wet weather continues, I would recommend a specific botrytis material such as Flint, Rovral, Vangard, Endura, or Pristine before bunch closure (the point where berries size up to the point where spray material cannot penetrate the cluster to protect fruit from infection). As always, check your Pest Management guide (New York & Pennsylvania or New England guides) and the label, rotate fungicide classes to reduce resistance likelihood, and follow all safety precautions when spraying. Organic disease management spray options include copper (DM, a little PM), sulfur (PM), stylet oil (PM, do not spray before or after a sulfur spray), and possibly some of the biologicals but I don’t know enough about them in regards to their performance against these late-season diseases.

Later this week would be a good time to scout clusters for grape berry moth (GBM) webbing which could suggest a need to treat for that insect pest. The threshold for treating this generation is 6% of clusters showing damage, which appears as small bits of webbing in between berries up inside the cluster. GBM is the primary insect pest of established vineyards in Vermont, and if it is the only pest insect need to manage, then some very specific materials with low potential for non-target effects may be used, including lepidopteran-specific materials like Bt, Intrepid, Delegate, or Altacor (the latter has some activity against Japanese beetle). Bt (DiPel and others) and Entrust would be effective materials against GBM for organic growers- the former affects only lepidoptera, while the latter would have some activity against Japanese beetle and some other insects as well.

None of this spray talk makes any sense if good cultural management isn’t practiced, and right now that means getting canopies in shape to best expose fruit to the sun for ripening and to control tangled shoot growth. Regardless of the training system used, this is an important tie to position canes. Most Vermont vineyards use a high wire systems, in which case shoots should be separated from one another and directed downward with some leaf pulling around clusters to put them in 50-100% sunlight. If using a low wire VSP or fan system, canes should be trained upward and, again, leaves pulled around clusters to expose them to sunlight. This is also a good time to remove laterals, non-fruitful canes, and any small clusters that are lagging behind the rest of the crop. This practice will arguably have the greatest effect on improving grape ripeness (assuming you have diseases relatively well-managed) of any you perform this year. It will also greatly improve the effectiveness of any spray materials that you do apply, at they can better penetrate the canopy and the canopy can dry better after wetting, which reduces disease pressure as well.

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.