July 1, 2025

By Becky Wiepz and Dan Kielar

Alert! High Spotted Wing Drosophila trap counts and confirmed presence in sweet cherry fruit

Station Updates

We are beyond the effective window for chemical thinners in apples. After fruit surpass 20mm, hand thinning is the only effective tool for cropload management.
Cherries continue to ripen and are now moderately vulnerable to SWD throughout the county.
Station staff are currently working on wildlife abatement in all perennial crops.

UW Madison/Extension Updates

Historic Growing Degree Day Comparison

Date 6/30	2021	2022	2023	2024	2025	20-year avg.
Base 50	813	684.5	770.5	799.5	702.5	730

GDD₅₀ continues to stay 3-5 days behind the 20-year average.

Recent Weather at Peninsular Ag Research Station

Date	Max Temp(℉)	Min Temp(℉)	Max Wind Gust(mph)	Daily Rain Total(in)
6/24	73.9	58.5	14.5	0.08
6/25	68.9	56.3	13.9	0.15
6/26	65.1	56.7	16.1	1.10
6/27	81.5	59.9	32.9	0.02
6/28	74.3	61.0	13.4	0.0
6/29	78.4	61.9	17.2	1.06
6/30	83.7	62.4	12.8	0.01

Upcoming forecast may result in infection periods for fungal and bacterial pathogens due to predicted rain events and warm temperatures.
If you’d like to see weather data for your area, visit https://wisconet.wisc.edu/

Apples

Growth Stage: Fruitlets above 20mm
Seasonal Update: To encourage return bloom next year, low level NAA applications should be applied 5-6 weeks after full bloom and again 7-10 days later.

Pest	Southern Door	Central Door	Northern Door	Notes
Tarnished Plant Bug	Present	Present	Present	Light pressure continues
Codling Moth	Adults Caught	Adults Caught	Adults Caught	Flight continues *see caption below
Oriental Fruit Moth	Adults Caught	Adults Caught	Adults Caught	Flight Continues
Plum Curculio				May be complete
Peach Tree Borer			First Catch

Biofix for codling moth is the first sustained catch, so is achieved in blocks that have catches more than one week in a row. For more information visit this article or the NEWA Codling Moth Model.

Disease	Southern Door	Central Door	Northern Door	Notes
Apple Scab	High Risk	High Risk	High Risk	Primary spore dispersal is nearly done. Check Apple Scab models on NEWA to time spray applications.
Fire Blight	Low Risk	Low Risk	Low Risk	Orchards should be monitored for shoot blight and strikes should be removed promptly, cutting 12-18 inches past the end of the canker.
Powdery Mildew			Some Strikes Noted	More pressure with hot and humid weather in the forecast.

Cherries

Growth Stage: Fruit is beginning to color
Seasonal Update: Fungicide should be applied before rain events as new leaves continue to expand. To check the rainfastness of your insecticide, visit this article from MSU and check your products accordingly.

Pest	Southern Door	Central Door	Northern Door	Notes
Spotted Wing Drosophila	High trap counts	High trap counts	High Trap Counts	Egg laying cannot occur until fruit is vulnerable. Fruit throughout the county is at moderate to high risk.
Cherry Fruit Fly	No Catch	No Catch	No Catch	Traps were placed last week, so far no adults present.

Disease	Southern Door	Central Door	Northern Door	Notes
Cherry Leaf Spot	High Risk	High Risk	High Risk	Risk increases with leaf area expansion and rain events
Powdery Mildew

Visit the Wisconet Pest & Disease Models page to check Cherry Leaf Spot for a weather station near you.

GRAPES

Growth Stage: E-L Growth Stage 27,
Seasonal Update: Fungicides should be applied before berry touch to protect your fruit through harvest.

Pest	Southern Door	Central Door	Northern Door	Notes
Japanese Beetles				None Caught at this time

Disease	Station	Notes
Grape Phomopsis	small amounts observed	Early season fungal control is critical at this time to prevent diseases like Phomopsis from spreading to economically damaging levels.
Phylloxera	None observed	monitor plants for galls on leaf undersides

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