Fruit IPM for September 2, 2020

Peach:

Peachtree Borers: The peachtree borer flight has peaked and most of the eggs have been laid and larvae emerged.

Where mating disruption has not been used, then insecticide treatments are usually required. Traditional treatments for this insect have focused on drenching the trunks and crowns with insecticides to kill newly emerged larvae that are still small and near the surface, before they burrow deep into the wood. Scaffold applications for the second generation of lesser peachtree borer (LPTB) can be done at the same time. The insecticide of choice has been various formulations of Lorsban or chlorpyrifos. This has always been a “second best” treatment since the timing (even now) is always late and after most larvae have already emerged. However since there is very little tolerance for Lorsban on the fruit, the label lists only the post-harvest application for borer control. Ideal applications have also required that the material be applied with a handgun in dilute applications so the spray material drenches the trunk and even pools at the bottom of the tree. Since practically nobody does this anymore, the practice has become less effective. Added to this is the fact that the longer one waits after all fruit is off, then the deeper the larvae borrow into the wood and the less effective the application becomes. Cortiva (formerly Dow), which makes Lorsban is stopping the manufacturing of the product at the end of the year due to low sales after the product was banned in California, New York, and the European Union. The product will still be available under the Chlorpyrifos name by Drexel, Adama, Gowan and others. Chlorpyrifos also comes with a bee warning. If you have pure grass middles and good weed control, then you shouldn’t have a problem. However if you have no to poor weed control, then you will have flowering weeds against the trees and bees in the orchard, making any use of chlorpyrifos against the label and therefore illegal. The boxed warning below was extracted from a commercial chlorpyrifos label.

Pollinator Warning on Chlorpyrifos Label:

During the past 6+ years, we have seen a number of growers switch to using mating disruption for lesser and greater peachtree borer control with good results. Some growers may want to consider that given the pending difficulties with our traditional approach, mating disruption merits increased attention.

Apple:

Codling Moth (CM): Trap captures remain above threshold in problem blocks in southern and northern counties, but in most cases are well below treatment levels. Several locations have trap counts that exceed 10-20 moths per trap. Treatments should be continued any time there are close to 5 or more moths per trap. Diamide products (Altacor, Voliam, Besiege, Exirel, Verdepryn), and Delegate are the products of choice. Under high populations, the additional use of the CM/OFM virus, Madex, can be helpful.

Stink Bugs and Apples: Populations are fairly low in most southern locations, but occasional damage is present. The story is different on a number of farms in Hunterdon, Middlesex and Morris Counties. Fully 1/3 of our farm sites in northern counties have economic populations of BMSB as defined by trap counts. In 1 case we found 51 stink bugs per trap this past week. A level of 10 BMSB/trap is considered high, and justifies weekly insecticide applications. If there is fresh injury inside the orchard, and the trap on the border is less than 10, then weekly treatments are still needed. Injury and bugs inside the orchard will always trump trap counts for spray decisions. Traditional wisdom is to apply frequent insecticide covers and supplement with border applications when needed every 7 days. The most effective materials for apples include: Actara, Belay, Danitol, Declare, Endigo, Lambda-Cy, Lannate (short residual), Leverage, Mustang Maxx, Proaxis, Renounce, Tombstone, Voliam Flexi and Warrior II. All of these materials are meant to kill the insects and prevent damage. In a recent article in “Scaffolds” from Cornell, Peter Jentsch referenced his research with several materials including Closer and Venerate. Closer has a 2ee label for BMSB suppression @ 5.75 fl oz/A with a 12 hr REI and a 7 day PHI. Venerate (4 qt/A) has an REI of 4 hr and a 0 day PHI. The materials’ suppressive nature relates to their antifeedant activities as confirmed in the Cornell research. While these materials don’t kill the bugs as would most other effective insecticides, they do discourage feeding and hence the damage. This can be particularly important in blocks of mixed varieties and PYO plantings where you might want materials that can be used with short REI and PHI restrictions. This is a novel approach to limiting BMSB damage. Venerate is a biological insecticide. It’s 2ee label can be found here. Growers in northern counties who have high BMSB populations and mixed variety blocks, may want to consider this option.

Oriental Fruit Moth (OFM): Populations are practically “0” in southern peach orchards and very low in northern peach orchards. However, due to the close dates of picking, insecticide use has stopped. Populations are higher in apple orchards, and a number of orchards have very high populations in northern counties. Remember that this is also an internal worm in apples. If you have high OFM trap counts (in peach or apple), but no to low codling moth pressure, DO NOT put the sprayer away. This last OFM generation can create quite a bit of havoc if not controlled. Also, any mating disruption dispensers that were used in peaches do not control OFM populations that are in apples, unless you used the CM/OFM dispensers in apples.

Grapes:

Spotted Lanternfly (SLF): While adults continue to become more common, several locations in northern counties have seen significant increases. SLF adults will commonly settle on the edge rows nearest a wooded border, which produces the highest populations. Adults can settle anywhere in the vineyard including trunks, all other plant parts, posts and stakes. Populations are expected to peak in late September to early October.

Fruit Flies (SWD and native Drosophilids): Populations of various fruit flies continue to be abundant. We are also starting to see sour rot develop in ripening grapes, often accompanied by fruit fly populations. As the flies lay eggs in the fruit and develop, they exacerbate the increase of sour rot. Therefor growers may wish to treat for both SLF and fruit flies in northern counties, but mainly fruit flies in southern counties. The enclosed list from last week has an added column for insecticide efficacy for those materials that be used for both SLF and fruit flies.

Tree  Fruit Trap Counts – Southern Counties

Tree  Fruit Trap Counts – Northern Counties

Blueberry:

Sharpnosed Leafhopper (SNLH): We are still watching for a significant increase in the adult trap catch, which would indicate the second generation flight. While we saw a slight increase this past week, it is still not enough and too early to think about second generation SNLH treatments.