By Becky Wiepz and Dan Kielar
Pest and disease development continues to be ahead of schedule for a typical season and Spotted Wing Drosophila pressure is high. Small fruits and cherries are vulnerable once they start to change color and should be protected with insecticide and harvested quickly to limit the chance of infection.
| Date 7/24 | 2020 | 2021 | 2022 | 2023 | 2024 | 20-year avg. |
| Base 50 | 1178.5 | 1238.5 | 1131 | 1194 | 1235.5 | 1190 |
GDD50 continues to be approximately 3-5 days ahead of the 20-year average.
Apples
Sampling for foliar nutrient tests should be done soon after terminal buds are set for the season. Taking 50 leaves from the middle of this years growth soon will yield the most accurate results.
Some growers are experiencing russet on certain varieties. A number of physical and biological factors can cause russet including frost, rain or high humidity, and some pathogens such as powdery mildew. Once present, russet can’t be cured, but plans can be made mitigate contributing factors in future seasons. To learn more about russet, and other apple skin disorders, see this article from Penn State Extension.
Insects
Wooly Apple Aphid (WAA) populations are increasing in orchards with dense canopies. The wet conditions are ideal for WAA development and we will likely see continued pressure from this pest.
Codling Moth populations continues to be very large this year. It appears we’re between flights at the moment. For more information on Codling Moth and it’s life cycle see this article from the UW Fruit Team.
Apple Maggot have emerged and flight has started. Insecticides applications should start in your orchard 7-10 days after flies are caught on yellow sticky boards, or immediately if they are caught on red spheres.
Tarnished Plant Bug and Potato Leaf Hoppers numbers are increasing with the dry weather and heat while Spotted Tentiform Leafminer’s second generation seems to be slowing down.
Disease
Blocks with good initial control are experiencing very low Apple Scab pressure and growers can stretch their applications out to every 10-14 days.
Powdery Mildew pressure continues to be high this year and new strikes should be scouted for regularly. Check the Midwest Fruit Pest Management Guide for chemical efficacy ratings.
Fireblight strikes may still appear in your orchards throughout the season, be sure to prune them out promptly. This article from Leslie Holland has more information on the latest recommendations for removing Fireblight strikes. Remember that Strep is not an effective tool for managing shoot blight.
Summer disease complex (Sooty Blotch and Flyspeck) may need controls to go out soon. Check the NEWA model to monitor pressure in your area. Save shorter PHI products for closer to harvest for managing late season rots.
Cherries
Harvest continues throughout the county!
Leaf samples for tissue testing should be taken soon for the most accurate results.
Insects
Spotted Wing Drosophila continues to be prolific throughout the county. All cherries are at risk and should be protected with full cover sprays on tight windows through harvest. Most insecticides that are effective against SWD are not rain-fast and require reapplication promptly after wetting events.
Cherry Fruit Flies have been caught throughout the county. Most insecticides that are effective against SWD are also effective against CFF but be sure to check the Midwest fruit pest management guide for efficacy ratings.
Disease
Control is going well for Cherry Leaf Spot throughout the county but post harvest sprays should go out within 7-10 days of harvest to ensure leaf retention as long as possible.
Powdery Mildew is still present in many blocks. Little can be done for this season but consider early season sulfur applications next year in blocks with heavy PM pressure. Check the Midwest fruit pest management guide for rate and timing recommendations.
A small amount of American Brown Rot has been detected in scouted blocks.
GRAPES
Grapes on the station are at bunch closure. Fungicides applied now will help protect the vines from bunch rot through harvest.
Insect pressure continues to be high, and the first Japanese Beetles have been detected in the county. Monitor your vineyards to assess activity and plan management.