August 10, 2026

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By Becky Wiepz and Dan Kielar

Station Updates

• Cherry harvest is complete throughout the county and finished this week.
• Fireblight strikes were observed throughout the county this week. At this time in the season your only management option is to prune out any observed strikes.

UW Madison/Extension Updates

• Managing Bitter Rot and Marssonina Leaf Blotch in Wisconsin Apple Orchards
• Wisconsin Fruit Crop Scouting Report: July 15, 2026
• Getting the Most Out of Summer Hedging in Your Apple Orchard
• 2026 Wisconsin Apple Growers Association Field Day Recap

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Historic Growing Degree Day Comparison

Date 7/28	2022	2023	2024	2025	2026	20-year avg.
Base 50	1206	1275.5	1299	1259.5	1562.5	1499

Recent Weather at Peninsular Ag Research Station

Date	Max Temp(℉)	Min Temp(℉)	Max Wind Gust(mph)	Daily Rain Total(in)
8/2	75	60	16.1	0.0
8/3	78	53	13.9	0.0
8/4	82	64	18.8	0.01
8/5	73	58	9.4	0.08
8/6	76	53	12.3	0.0
8/7	81	63	18.3	0.0
8/8	80	65	15	0.0
8/9	76.3	61	13.4	0.0

Apples

Growth Stage: Terminal buds are setting, particularly in Honeycrisp and early varieties.
Seasonal Update: Foliar sampling for nutrient testing should be done between July 20th and August 7th or whenever terminal buds start to set.

Pest	Presence	Notes
European Red Mite	Present throughout county	Monitor now for build up from the hot and dry weather in July, spray only if needed
Borer species	Present	Currently, American Plum Borer and Lesser Peach Tree Borer are in flight
Codling Moth	Second generation flight is slowing down but some blocks continue to have high trap counts	2nd generation sprays should go out with a follow-up spray 10-14 days later
Apple Maggot	Still only a few have been caught throughout the county	Egg laying will start 7-10 days after first catch
Leaf rollers	Flight continues	Red banded leaf roller continued high numbers are up and oblique banded leaf rollers seem to be decreasing
Spotted Tentiform Leaf Miner	Present	2nd generation currently active
Japanese Beetles	Present and building populations

Disease	Presence	Notes
Apple Scab	Lesions detected throughout door county on leaves and fruit	Primary spore dispersal is complete. If control was good, sprays can be stretched to 10-14 days between applications. If pressure early in the season was high or lesions are evident on fruit continue tighter spray windows.
Fire Blight	New strikes detected throughout the county this week	Orchards should be monitored and strikes should be removed promptly, cutting 12-18 inches past the end of the canker.
Powdery Mildew	Late season active. Strikes detected throughout the county	If present, include a product that specifies control on the label and plan on and early season application of sulfur next year.
Sooty Blotch/Flyspeck/Summer Rots	None detected	Apply preventative sprays before rain events, using NEWA models to determine spray timing.

Cherries

Growth Stage: Harvest complete in most of Central and Southern Door County
Seasonal Update: Terminal buds have set. Foliar sampling for nutrient assessment should be done soo

Pest	Presence	Notes
Spotted Wing Drosophila	Heavy flight continues throughout county	Fruit is vulnerable throughout the county and insecticides should be used to protect fruit through harvest. To prevent insecticide resistance from developing, do NOT spray insecticides after harvest.
Cherry Fruit Fly	Adults Detected throughout county
Borer species	American Plum Borer and Lesser Peachtree Borer adults caught	Targeted sprays should go out 7-10 days after first catch followed by a second application 10-14 days later.
European Red Mites	A few adults present throughout the county. Some blocks have increasing population near threshold.	Monitor population build up and spray only if needed

Disease	Presence	Notes
Cherry Leaf Spot	Yes	Heavier pressure due to recent rain events, but keep track of sprays during harvest to prevent flareups.
Powdery Mildew	Still some active lesions throughout the county.	High temperatures and humidity are increasing the pressure and spread of PM. Check your blocks if you are unsure. If present, include a product that specifies control on the label and plan on and early season application of sulfur next year.

GRAPES

Growth Stage: E-L Growth Stage 29
Seasonal Update: Shoot thinning and leaf removal to increase light exposure on fruit clusters should be done now. Also consider netting early varieties due to high bird pressure.

Pest	Presence	Notes
Leaf Hoppers	Yes
Phylloxera	Some galls observed
Red Banded Leaf Rollers	Yes
Japanese Beetles	Populations are building.	Observed in other cropping systems and off station.

Disease	Presence	Notes
Black Rot	Single Lesions Observed	Early season fungal control is critical to prevent diseases from reaching economically damaging levels.
Powdery Mildew	None Detected	Risk will increase with current heat and humidity. Scout your orchard to determine local pressure.
Downey Mildew	None Detected	Risk will increase with current heat and humidity. Scout your orchard to determine local pressure.

Additional Resources

• Apple Nutrient Sampling
• Financial Decisions for Tart Cherry Crops with Variable Yields
• Take Steps To Ensure That You’re Complying With the EPA Herbicide Strategy To Protect Threatened and Endangered Species