Thank you for following along this season! This will be the final report for the 2025 growing season.At the West Madison research station, weather over the past two weeks (September 11-24) has remained mild, with the average high temperature of 78.3℉, average low temperature of 60.4℉ and a total of 0.98 inches of precipitation (NEWA: Verona). Growers can reference the Midwest Fruit Pest Management guide for further information on pest management best practices, including recommended chemical best practices. 

Grapes

Phenology 

At the West Madison Agricultural Research Station (WMARS) in Madison, WI, all table and wine grapes have been harvested as of September 24, 2025. The Peninsular Agricultural Research Station just wrapped up table grape harvest as of September 23, 2025.

Growing Degree Day (GDD) Accumulations

Below displays the GDD accumulations from April 1 through September 24 for the current and last two seasons. This data is collected using the NEWA website. You can visit their “About degree days” page to learn more about the concept of degree days as well as the formulas utilized for calculations.

Growing degree day (GDD) accumulation as of September 24 (April 1 start date; base 50°F BE*) at the WMARS and PARS.

Location	2025	2024	2023
Verona WMARS	2645	2717	2764
Sturgeon Bay PARS	2048	2180	2142

*BE = Baskerville-Emin calculation method

Maturity Testing – Titratable Acidity and Brix

Below displays brix and acidity testing results for both table and wine grapes at WMARS between August 6 and September 24. Harvest dates include:

• August 27: Reliance, Somerset Seedless, and MN1369
• September 2: Mars and MN1325
• September 4: Brianna
• September 8: Marquette
• September 22: Petite Pearl
• September 24: La Crescent and Frontenac

Pests and other considerations

• Black rot and fruit rot symptoms continue to be reported in vineyards around WI. Review this 2022 article by Dr. Leslie Holland on Fruit and Cluster Rots for more information on black rot and fruit rot management around harvest.
• Downy mildew may impact grape quality at harvest. Read more about signs/symptoms and management in this 2024 WI Fruit News article on late-season downy mildew.
• Grape growers dealing with uneven ripening may reference this 2024 WI Fruit News article: Understanding and Addressing Uneven Ripening in Grapes.
• Continue monitoring Spotted wing drosophila traps through harvest.
• Wasps: Review this Wisconsin Fruit News article from 2020 for more information on wasp monitoring and management: September 3, 2020 Scouting Report.
• Sanitation: Remove and destroy (chop/compost) fallen or rotting fruit ~weekly to prevent any internally developing larvae from reaching maturity, and to limit the spread of disease.
• Reminder: Always read and follow directions on the label and keep in mind pre-harvest intervals (PHI) as we move through harvest!

Apples

Phenology

In southern Wisconsin, common varieties like Honeycrisp, Cortland, Gala and Crimson Crisp are currently being picked. At the Peninsular Ag. Research Station, harvest is underway, peaking this week. This has been a generally a heavy fruiting season for many apple growers in Wisconsin.

Growing Degree Day (GDD) Accumulations
We are tracking growing degree days (DD 43 °F BE) from January 1 to monitor bud development in apples. This data is collected using the NEWA website. You can visit their “About degree days” page to learn more about the concept of degree days as well as the formulas utilized for calculations. Growing degree day (GDD) accumulation in 2023, 2024 and 2025 as of September 24 (January 1 start date; base 43°F BE*).

Location	2025	2024	2023
Verona WMARS	3781	3919	3833
Sturgeon Bay PARS	3035	3268	3144
Gays Mills	3784	3855	3844
Eau Claire	3480	3489	3630
Fond Du Lac	3457	3781	3766
Racine	3659	4090	3721

*BE = Baskerville-Emin calculation method

Other considerations:

• Continue to keep an eye on degree-day accumulation for codling moth based on trap biofix in your area through harvest.
• Apple maggot will emerge through September. Growers should continue using red sphere traps to monitor fall population levels through harvest.
• Brown marmorated stink bug has been observed at West Madison.
• Check out the WI DATCP Orchard Insect Pest Bulletin for more information on current insect trap captures across the state.
• Sooty blotch and flyspeck continues to be observed in Southern WI. Continue monitoring NEWA models and scout susceptible varieties.
• Sun scald and southwest injury to trunks and branches has been observed across many orchards and vineyards this summer, likely due to wide variations in winter temperatures that may lead to cracking.
• Fruit sunburn and bird injury has been observed across many fruit crops in southern WI. Consider removing this fruit while out picking to prevent other pests attracted to the volatiles released from impacting fruit.
• Sanitation: Remove and destroy (chop/compost) fallen or rotting fruit ~weekly to prevent any internally developing larvae from reaching maturity, and to limit the spread of disease.
• Reminder: Always read and follow directions on the label and keep in mind pre-harvest intervals (PHI) as we move through harvest!

That’s all for this season, thanks for following along. Best wishes to all WI fruit growers through the rest of harvest and the winter season!

This article was posted in Apples, Disease, Grapes, Insects and tagged Amaya Atucha, Apples, Courtney Meeks, disease, gdd, Grape Acidity, Grape Brix, Grapes, growing degree day accumulations, Growing Degree Days, insects, Josie Dillon, Leslie Holland, pests, phenology, Wisconsin Fruit Crop Scouting Report.