June 13, 2025

By Becky Wiepz and Dan Kielar

Station Updates

Chemical thinning applications ongoing in apples.

UW Madison/Extension Updates

Historic Growing Degree Day Comparison

Date 6/12	2021	2022	2023	2024	2025	20-year avg.
Base 50	540	371	499.5	514.5	403.5	450

GDD₅₀ has fallen behind the 20-year average by about 3-5 days.

Recent Weather at Peninsular Ag Research Station

Date	Max Temp(℉)	Min Temp(℉)	Max Wind Gust(mph)	Daily Rain Total(in)
6/6	73.6	52.5	13.9	0.0
6/7	73.2	54.9	11.6	0.0
6/8	66.7	53.6	20.6	1.17
6/9	64.0	53.6	18.3	0.04
6/10	66.2	54.1	17.9	0.0
6/11	80.4	52.7	15.7	0.0
6/12	65.8	52.3	15.0	0.01

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

Apples

Growth Stage: Initial Fruit Set
Seasonal Update: Plant Growth regulators are most effective for cropload management when fruitlets are small. Applications should be done soon.

Pest	Southern Door	Central Door	Northern Door	Notes
Tarnished Plant Bug	Present	Present	Present	Flight continues
Spotted Tentiform Leafminer	Present	Present	Present	Flight continues
Codling Moth	Adults Caught	Adults Caught	Adults Caught	Flight continues *see caption below
Oriental Fruit Moth	Adults Caught	Adults Caught	No Catch	Flight Continues

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	Increased risk with increased leaf surface and rain. Check Apple Scab models on NEWA to time spray applications.
Fire Blight	Low Risk	Low Risk	Low Risk	End of bloom significantly decreases infection potential.

Cherries

Growth Stage: Past Shuck Split
Seasonal Update: Fungicide should be applied before rain events as new leaves continue to expand. Once fruit is out of the shuck, insecticide should be applied for Plum Curculio.

Pest	Southern Door	Central Door	Northern Door	Notes
Plum Curculio	No Scarring	No Scarring	No Scarring	Fruit is not at risk of PC damage until after shuck split
Spotted Wing Drosophila			1 Adult Caught	Egg laying cannot occur until fruit is vulnerable. Check fruit progression using the model from Wisconet.

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

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 12-13
Seasonal Update: Pre-Bloom fungicide should be applied soon, as appropriate for your cultivar. Shoots should be thinned to ~2 per spur while shoots are still short.

Pest	Southern Door	Central Door	Northern Door	Notes
Flea Beetles	Low risk	Low risk	Low risk	Spring damage on swelling buds is the only feeding that poses economic risk.

Disease	Station	Notes
Grape Phomopsis	None observed
Phylloxera	None observed	monitor plants for galls on leaf undersides

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