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 6/302021202220232024202520-year avg.
    Base 50813684.5770.5799.5702.5730
    GDD50 continues to stay 3-5 days behind the 20-year average.

    Recent Weather at Peninsular Ag Research Station

    DateMax Temp(℉)Min Temp(℉)Max Wind Gust(mph)Daily Rain Total(in)
    6/2473.958.514.50.08
    6/2568.956.313.90.15
    6/2665.156.716.11.10
    6/2781.559.932.90.02
    6/2874.361.013.40.0
    6/2978.461.917.21.06
    6/3083.762.412.80.01
    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.

    PestSouthern DoorCentral DoorNorthern DoorNotes
    Tarnished Plant BugPresentPresentPresentLight pressure continues
    Codling MothAdults CaughtAdults CaughtAdults CaughtFlight continues
    *see caption below
    Oriental Fruit MothAdults CaughtAdults CaughtAdults CaughtFlight Continues
    Plum CurculioMay be complete
    Peach Tree BorerFirst 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.
    DiseaseSouthern DoorCentral DoorNorthern DoorNotes
    Apple ScabHigh RiskHigh RiskHigh RiskPrimary spore dispersal is nearly done. Check Apple Scab models
    on NEWA to time spray applications.
    Fire BlightLow RiskLow RiskLow RiskOrchards should be monitored for shoot
    blight and strikes should be removed promptly,
    cutting 12-18 inches past the end of the canker.
    Powdery MildewSome Strikes NotedMore 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.

    PestSouthern DoorCentral DoorNorthern DoorNotes
    Spotted Wing DrosophilaHigh trap countsHigh trap countsHigh Trap CountsEgg laying cannot occur until fruit is
    vulnerable. Fruit throughout the county is at moderate to high risk.
    Cherry Fruit FlyNo CatchNo CatchNo CatchTraps were placed last week, so far no adults present.
    DiseaseSouthern DoorCentral DoorNorthern DoorNotes
    Cherry Leaf SpotHigh RiskHigh RiskHigh RiskRisk 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.

    PestSouthern DoorCentral DoorNorthern DoorNotes
    Japanese BeetlesNone Caught at this time
    DiseaseStationNotes
    Grape Phomopsissmall amounts observedEarly season fungal control is critical at this time
    to prevent diseases like Phomopsis from spreading
    to economically damaging levels.
    PhylloxeraNone observedmonitor plants for galls
    on leaf undersides

    Additional Resources