Fruit Crop Pest Report- May 21, 2019

2019 Fruit Pest Update

May 21, 2019

2019 – 2020 Midwest Fruit Pest Management Guide

Even with temperatures in the low 40s, there was an apple scab infection period at all the weather stations in Door and Kewaunee counties this weekend. There was an average of 50 hours of leaf wetness recorded. Symptoms from any infections that may have occurred would be apparent in about 7-10 days.

Due to the cool temperatures, nothing has progressed much from last week. Apples at the station are still at tight cluster in most blocks and apple scab sprays should be ongoing on a 7-10 day schedule for susceptible varieties (see disease section below).

Cherries have progressed a bit and are approaching open cluster. There is a bit of green fruitworm feeding on the buds at the station, but no action is needed. Grapes are finally moving a bit and bud scales are opening. .

Below is a degree day comparison of the last five years. We are at about half the degree day accumulations from average. Based on MSU enviroweather models, we are about 7-14 days behind normal growing degree days base 50 (see map to the right).

Date 5/13	2015	2016	2017	2018	2019	5 yr avg
Base 50	151	124	105	154	63	120

INSECT & DISEASE CONTROL

APPLE

Disease Pressure – Apple scab spray programs should be ongoing to protect apple scab susceptible varieties (e.g. McIntosh and Cortland), as the 1/2 inch green through first cover time period is the most critical time for primary scab infections to occur. Keep these varieties covered with fungicide treatments through the end of primary scab season; typically mid to end of June in Northeast WI. Applications of copper can still be made to reduce fire blight inoculum. These copper sprays will also provided protection from apple scab infection.

Insect Pressure – Green fruit worm adults continue to fly and lay eggs. Scout for presence of their hatching larva as well as overwintering oblique-banded leafroller larva starting at the ½ inch green stage of development through petal fall.

So far, no plum curculio adults have been caught. Codling moth traps were placed in orchards county-wide last week.

CHERRY

Disease Pressure – Little to worry about because of plant stage. Fungicide applications targeting cherry leaf spot will need to begin after bract leaves begin to unfold, so probably not for another few weeks.

Insect Pressure – Green fruit worm adults continue to fly and lay eggs. Once significant leaf tissue begins to develop, scout for presence of their hatching larva as well as overwintering oblique-banded leafroller larva

Spotted wing drosophila traps were placed in select orchards last week; traps will be placed county wide this week.

GRAPE

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

Disease Pressure – Little to worry about because of plant stage

Insect Pressure – I found a tiny bit of flea beetle damage on buds at the research station. As buds begin to swell, keep an eye out for grape flea beetle damage (see WI Fruit News article in Issue 2 at the link below).