Fruit Crop Pest Report- July 1

2019 Fruit Pest Update

July 1, 2019

2019 – 2020 Midwest Fruit Pest Management Guide

Temperatures are finally rising, so things are moving along more quickly. Apples are about 20-30mm in size. Sweet cherries are starting to get a rosy blush, and tarts are still green, but sizing. Grapes are pre-bloom to bloom.

Below is a degree day comparison of the last five years.

Date 7/1	2015	2016	2017	2018	2019	5 yr avg
Base 50	557	658	596	769	488	605

INSECT & DISEASE CONTROL

APPLE

Disease Pressure – Based on the enviroweather RIMpro model, apple scab ascospores are fully matured but there is still a small chance that some are discharging. If we get rain in the coming week, there still is the potential for an apple scab infection period. Scout carefully for apple scab lesions, and if control was good so far, sprays can be stretched to 2-3 week intervals. Apple growers who have scab lesions present in their orchards should continue to apply protectant fungicides on a regular schedule.

Fireblight strikes haven’t been detected, but there is still the potential for infection, especially as temperatures warm or if there is hail or damaging winds. Powdery mildew hasn’t been detected yet, but there is a higher pressure with warmer temps, and dry but humid weather.

Insect Pressure – First generation codling moth are at biofix at most orchards, indicating the beginning of the adult flight. Sprays for codling moth can go out around 100 to 250 degree days base 50, depending on the product used. We have been getting about 15 – 20 GDD per day. Therefore, sprays would begin midweek. A second spray can be used 10-14 days later. Plum curculio still haven’t been caught in traps, but they are active. Spotted tentiform leafminer levels are low, and they are at the sapfeeding stage and cannot be controlled at this time, regardless. There are still a few oblique banded leafrollers adults active. European red mite numbers remain low.

CHERRY

Disease Pressure – – Cherry leaf spot pressure remains very high and it is important to stay on a tight spray schedule. With the increase in temperatures expected, copper products and Syllit should be avoided to avoid phytotoxicity. Do not use Bravo fungicides since fruit is past shuck split. Powdery mildew pressure will also increase as temperatures warm.

Insect Pressure – So far there has been very little insect damage seen in most cherry blocks. There have not been any spotted wing drosophila, plum curculio, or cherry fruit fly caught. There is also very low levels of leaf feeding and even lower levels of fruit feeding observed, so no spray is needed. Cherry fruit fly traps will be placed in orchards this week. Even though there haven’t been plum curculio caught, a protectant insecticide is recommended, since egg-laying could result in larvae be present in fruit at harvest. Make sure to check the preharvest interval of any product you choose. Continue to scout for European red mites, especially in blocks where there has been a lot of use of pyrethroids for SWD control in the past few years.

SWD has not been caught in Door County, but the first one was caught in Wisconsin this past week. See this article for the details: https://fruit.wisc.edu/2019/06/26/first-detection-of-spotted-wing-drosophila-in-wisconsin-for-2019/ Cherries are not susceptible to SWD damage until after straw color begins to develop.

GRAPE

Mark your calendar for July 18, 3-5pm, for the 2019 Vineyard Walk at the Peninsular Ag Research Station!

Disease Pressure – Disease pressure is greatly increasing, especially with the warmer temperatures. Grapes are highly susceptible to diseases during bloom and post bloom, so spray programs should be ongoing. When scouting for diseases, former UW graduate student, Dave Jones, made an excellent photo disease guide per variety that can be found here: https://fruit.wisc.edu/wp-content/uploads/sites/36/2017/04/Photo-guide-diseases-cold-climate-grape.pdf.

Insect Pressure – A few flea beetle larvae and grape plume moth larvae are showing up. Larval damage rarely reaches economic levels.