Fruit IPM for 8/4/2020

Grapes:

Spotted Wing Drosophila (SWD): The spotted wing drosophila is an invasive fruit fly which can infest sound ripe thin-skinned fruit. The SWD female has a saw-like ovipositor which she uses to literally saw through healthy skin and deposit her eggs, which develop into small maggots. At this time of year each generation takes slightly over 1 week to complete. Each female can lay about 300 eggs over her lifetime, and given the time of year it is, we will probably see 3-5 more generations by the time grapes are harvested. Over the past several years we have monitored SWD in vineyards during August through September. A well-known link exists between high populations of native fruit flies and the prevalence of late season sour rot in grapes. What we don’t know is how the prevalence of SWD might be able to aggravate or help increase the late season populations of native fruit flies, or if the total fruit fly complex (native and invasives) is higher because of the presence of SWD.

We have been monitoring SWD populations in blueberries since early May, and are changing our focus to grapes during the latter part of the summer, and after blueberries have been picked. Populations of all fruit flies have built up since May, so as veraison starts, berries start to touch, and sugars start to increase, fruit flies can have more of an impact. Total fruit flies per trap over the last 3 weeks (northern counties) is summarized below, and is already significantly higher that it was in blueberries during June and most of July:

Total fruit flies per trap – In northern county grapes starting late July

Spotted Lanternfly (SLF): SLF nymphs have been found in numerous vineyards since May. After initial treatments, SLF nymphs largely ‘disappeared’, or actually were feeding on wild hosts and maturing from egg masses originally laid in wooded areas and on other non-cultivated plants. Those nymphs are starting to mature, and adults are starting to be seen in scattered areas throughout the state, but especially in northern counties. SLF adults and grapes are not something you want to see together. From now through September, we expect to see increasing levels of adults in vineyards. SLF adults will commonly settle on the edge rows nearest a wooded border. Grapes cannot survive sustained high populations. If you are in an area with established populations (e.g. Hunterdon, Warren and other northern counties), then you may wish to treat when SLF adults first arrive, using a longer residual product with a longer PHI. Researchers at Penn State have suggested that these August treatments might include Actara (14 day PHI), or Brigade/Bifenture (30 day PHI). Insecticides that have shorter PHIs and residual activity should be used later and will need to be reapplied as populations and weather conditions dictate. These include some of the other pyrethroids like Mustang Maxx (1 day PHI), or the neonicotinoid, Scorpion and Venom (1 day PHI).

Disease Management at Bunch Closure: Targets at bunch closure are Botrytis; Foliar Downy Mildew, and rots. Dr. Mizuho Nita at Virginia tech has shared his presentation online for late season disease management.  He also provides a list of Grape fungicides with short PHI’s.

Peach:

Stink Bugs Apples and Peaches: Brown Marmorated Stink Bug (BMSB) has generally reflected low populations. However this is not true for all farms. The higher populations are in northern counties where we have 25 trap locations, with 4 of those showing populations at or exceeding 8 bugs per trap per week. Three of these locations are in Morris County and 1 in Middlesex County. At minimum, growers who have traps with these kinds of levels should be applying weekly border sprays of BMSB effective materials. Our traps are placed on the orchard/woods borders. High numbers on the orchard border will often reflect BMSB inside the orchard. A regular 7 day schedule is required to minimize damage if BMSB is already in the interior of the orchard. Most, but not all of the pyrethroid  and pyrethroid premixes have good activity for BMSB. See the 2020 NJ Tree Fruit Production Guide for a list of effective materials.

Oriental Fruit Moth (OFM): We are at the treatment timing for the third generation, but there is little to no pest pressure in southern counties. In northern counties populations are more evident. See the updated timings below for northern counties:

Scale Insects: Both White Peach Scale and San Jose Scale second generation crawlers are active at this time. White Peach Scale will be active through mid-month and San Jose through August into early September. Growers who have scale problems should not let this insect go, since they can kill scaffold branches and entire trees. Dilute applications of Diazinon, and Esteem are both effective when directed against the crawlers.

Apple:

Codling Moth (CM): Trap captures are very low statewide, but treatments should be completed if there are close to 5 or more moths per trap. Some farms in Hunterdon, Sussex, Morris and Middlesex Counties have over 6-24 males per trap. This represents a problematic population and needs to be controlled. Make sure that your spray penetrates the insides and tops of the trees, since this is where much of the mating and egg laying takes place. 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.

European Red Mite (ERM): European red mite populations have been building over the past week to 10 days. While only a few orchards have significant mite populations, given the heat, populations have been able to increase rapidly. In many cases healthy population of Stethorus punctum, the small black lady beetle, and predaceous mites are present in controlling numbers. When allowed to reproduce, these will turn the tide and reduce the mite populations to below economically damaging levels. As we approach the middle of August, the mite populations have to be very high to justify a treatment. This, combined with the fact that predators are present in many orchards, means the miticides are not needed in these instances.

Rots : Various rots, mostly bitter rot are still appearing in some orchards. Bitter rot infections will continue during wetting periods for the rest of the summer.  The QoIl premixes Merivon and Pristine are good rot materials with Merivon being the better of the two. Luna Sensation and Luna Tranquility are also rated as effective. Alternate with a Captan/Prophyt mix or Captan/Topsin. Topsin has some efficacy for white and black rots but is not effective against bitter rot.

Scouting Calendar Tree Fruit Southern Counties

The following table is intended as an aid for orchard scouting. It should not be used to time pesticide applications. Median dates for pest events and crop phenology are displayed. These dates are compiled from observations made since 1995 in Gloucester County. Events in northern New Jersey should occur 7-10 days later.

 Tree  Fruit Trap Counts – Southern Counties

Tree  Fruit Trap Counts – Northern Counties

Blueberry:

Spotted Wing Drosophila (SWD) : This is the only pest of concern, and only on the latest varieties. The average Elliott field will require only 1-2 more treatments.

Aphids: Aphid populations are down to an average of .24% of terminals infested with a high of 8% last week. Aphid populations are now done for the season, and no further treatments are needed.

Putnam Scale: There is no change since last week. Scale infested fruit remains very low. Crawler traps have been put out, and the second generation should be starting in the near future.

Post-Harvest Treatments: These will need to be targeted specifically for Sharpnosed Leafhopper and Putnam Scale, if needed. These insects generally require different materials at different timings. So there is No Such Thing as a “Clean-Up Spray,” but rather some targeted post-harvest sprays, applied for specific pests when needed. Second generation leafhopper applications should target close to the peak flight of second generation adults, which should start to appear the second half of August. Scale treatments should be applied in fields which had 1^st generation scale problems during early July. Second generation crawlers should start to appear any time now.

By the Numbers – Blueberry Trap Counts: