2019 Fruit Pest Update
June 10, 2019
Apples are primarily at petal fall and cherries are at shuck split. Grapes are around 4-5” shoots.
Below is a degree day comparison of the last five years. We are still about a week behind average.
|Date 6/10||2015||2016||2017||2018||2019||5 yr avg|
INSECT & DISEASE CONTROL
Disease Pressure – Apple scab infection periods continue to occur at all the stations. We are at about 95% ascospore maturity and 70% ascospore discharge. Primary apple scab season will end when spores are 100% discharged. Apple scab spray programs should be ongoing to protect apple scab susceptible varieties through the end of primary scab season. So far there haven’t been any apple scab lesions detected in sprayed orchards.
Apples are susceptible to fire blight if blossoms are open and temperatures are over 60F. Any wetting (rain, fog or dew) can then trigger an infection. Protectant applications of a bactericide should be made every 4-5 days during the bloom period.
Insect Pressure – Do NOT use insecticides during bloom that harm pollinators. A light spotted tentiform leafminer is continuing, but no other insects were caught last week (coding moth, plum curculio, green fruitworm, or obliqubanded leafroller). Plum curculio levels are increasing around the state, so they will likely be caught any day around here. Continue to scout for green fruitworm and obliquebanded leafroller damage through petal fall as there has been some light blossom feeding being observed.
At full and post bloom, consider crop load and use flower and fruit thinners as needed. There has been substantial information about precision thinning tools in the Wisconsin Fruit News which can be found here: https://fruit.wisc.edu/crop-management-newsletters/
Disease Pressure – – Cherry leaf spot has been detected in some blocks. If wet weather continues, it will be important keep a tight spray coverage window and use full cover sprays at full rates to keep the disease under control. Note: Do not use Bravo fungicides if fruit is past shuck split.
Insect Pressure – So far there haven’t been any plum curculio adults or spotted wing drosophila flies caught in traps. Spotted wing drosophila was caught in Michigan and Minnesota over the past week, but fruit are not susceptible to damage at this point. Continue to scout for green fruitworm and obliquebanded leafroller damage through petal fall.
Michigan State University recently published an article, “Low spray programs for tart cherry.” Just make sure to check that any product you use is registered for Wisconsin.
Mark your calendar for July 18, 3-5pm, for the 2019 Vineyard Walk at the Peninsular Ag Research Station!
There are reports from around the state of significant winter injury on grapes. Evaluate your vineyard for winter injury since that will have implications on canopy and cropload management this season.
Disease Pressure – Fungicide applications can begin around 4” – 6”growth
Insect Pressure – Buds that haven’t burst could still be susceptible to grape flea beetle damage. Numbers at the Peninsular Station were very low.
Wisconsin Fruit News: New issue this week
WFN-Vol. 4, Issue 5 (June 7, 2019)
- Strawberry angular leaf spot
- Grape downy mildew
- Chlorpyrifos update
- Apple thinning update
- Door County Report
WFN-Vol 4, Issue 4 (May 24, 2019)
- Risks and benefits of reducing herbicide rates
- Winter damaged blueberries
- Eastern berry thrips
- Bitter pit management
- Door County Report
- NEWA new weather monitoring partnership
- Malusim app released
- Insect diagnostic lab update
- Controlling mites in berries
- Impact of rain on fungicides
- Blossom thinning
Links to individual Enviro-Weather stations: