By Becky Wiepz and Dan Kielar
Station Updates
- Bloom is progressing throughout the county with most cherries at or approaching full bloom
- Mulching of orchards and vineyards is in progress on the Station
UW Madison/Extension Updates
- Apple Crop Load Management Starts Now: Tips for Bloom Thinning
- Thinning Decisions and Weather Outlook for Wisconsin Apple Growers
- Wisconsin Orchard Update: Fire Blight Management
- Wisconsin Orchard Update – May 16, 2025: Managing Fire Blight After a Hailstorm During Bloom and Petal Fall
- Notes from the Field: A Growers Perspective – Ben Kraus Chat #3
- Event: Mount Horeb, WI – Organic Orchard Floor Management Field Day – June 11, 2025
- Event: Stillwater, MN – Upper Midwest Honeyberry Academy – July 1, 2025
Historic Growing Degree Day Comparison
| Date 5/21 | 2021 | 2022 | 2023 | 2024 | 2025 | 20-year avg. |
| Base 50 | 212 | 187.5 | 220 | 280.5 | 186 | 204 |
Recent Weather at Peninsular Ag Research Station
| Date | Max Temp(℉) | Min Temp(℉) | Max Wind Gust(mph) | Daily Rain Total(in) |
|---|---|---|---|---|
| 5/15 | 71.2 | 52.2 | 19.5 | 0.61 |
| 5/16 | 68.4 | 52.7 | 28.9 | 0.15 |
| 5/17 | 61.3 | 50.7 | 19.9 | 0.04 |
| 5/18 | 50.7 | 38.3 | 19.5 | 0.0 |
| 5/19 | 50.4 | 37.9 | 17.2 | 0.0 |
| 5/20 | 46.9 | 42.3 | 24.4 | 0.53 |
| 5/21 | 53.1 | 42.1 | 21.0 | 0.15 |
If you’d like to see weather data for your area, visit https://wisconet.wisc.edu/
Apples
Growth Stage: Late Pink to Full Bloom, depending on variety
Seasonal Update: Avoid Insecticide Application when blooms are open to protect pollinators. Prepare for apple thinning: strategies and chemistries.
| Pest | Southern Door | Central Door | Northern Door | Notes |
|---|---|---|---|---|
| Green Fruit Worm | Moths Caught | Moths Caught | Moths Caught | End of Flight |
| Tarnished Plant Bug | Adults Caught | Adults Caught | Adults Caught | |
| Spotted Tentiform Leafminer | Present | Present | Present | Mid-Flight |
| Codling Moth | No Catch | No Catch | No Catch | |
| Blossom Feeders/Lepidoptera | Low Pressure | Low Pressure | Low Pressure | |
| Oriental Fruit Moth | First Catch | No Catch | No Catch | Start of Flight |
| Disease | Southern Door | Central Door | Northern Door | Notes |
|---|---|---|---|---|
| Apple Scab | Medium Risk | Medium Risk | Low 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 | No Risk | Warm temperatures and rain can lead to growth and spread of fireblight bacteria. When blossoms are open, protective sprays should be used. |
Cherries
Growth Stage: Full Bloom
Seasonal Update: Fungicide should be applied before rain events now that bract leaves are open throughout the county.
| Pest | Southern Door | Central Door | Northern Door | Notes |
|---|---|---|---|---|
| Disease | Southern Door | Central Door | Northern Door | Notes |
|---|---|---|---|---|
| Cherry Leaf Spot | Low Risk | Low Risk | Low Risk | Risk increases with leaf area expansion and rain events |
GRAPES
Growth Stage: Budburst; leaf tips visible
Seasonal Update: As shoots expand, scouting and treating for fungal pathogens is critical.
| Pest | Southern Door | Central Door | Northern Door | Notes |
|---|---|---|---|---|
| Flea Beetles | Low risk | Low risk | Low risk | Increasing risk as temperatures climb |
| Disease | Southern Door | Central Door | Northern Door | Notes |
|---|---|---|---|---|