Current Wisconsin weather and climate conditions

• A rainy end to the month of June brought 2-4” of rain across most of northern and western WI, bringing 30-day totals up to 110-150+% of average. Totals were lower to the south and east, where 30-day totals were slightly below average.
• Late June conditions were very warm and muggy in WI, with temps in the south 4-6°F above normal. Accumulated GDD’s since May 1st are now running ahead of normal pace across most of the state.

Impact

• Abnormally wet soil moisture conditions are common across the west and north where rainfall totals were higher last week. Wisconet research farm stations show jumps in 4” soil moisture at most sites.
• The area of the state in D0 (abnormal dryness) decreased from last week, while D1 drought remains unchanged in the far south.
• Corn and soybean development are running at a pace near to the 5-year normal for both crops, with blooming underway in soybeans. Crop condition for corn, soybeans, and wheat showed no change to minimal change from last week (Source: NASS).

Outlook for Wisconsin weather and climate

• Next week will bring more rain chances, with higher chances in the west-central and northwest counties.
• Mid-July climate probabilities are showing a lean towards above normal temperatures and near normal precip across almost all of WI.
  • Be aware of a moderate to major level of heat risk on the 4th of July and the holiday weekend in general.
• The outlook for July indicates a lean towards warmer than normal with precip uncertainty (outlook updated on 6/30).

Agronomic considerations

• Field Work and Conditions
  • Avoid trafficking fields in moist conditions to prevent compaction. ​
  • See these considerations for early season corn management. ​
  • Crop growth rebounded this week with warm temperatures and a gain of GDD this past weekend. ​
  • Corn is reaching the growth stage appropriate for taking presidedress soil nitrate tests (PSNT).
• Manure Applications
  • Reminder of Wisconsin’s NR 151 Runoff Rules with the timing of manure spreading and current runoff levels. Check DATCP Runoff Risk Advisory Forecast.
• Pest Management ​ 
  • Scout fields to note which weed species are emerging and/or which species escaped herbicide application.​
  • As corn and soybean crops grow, note growth stages to time future applications and sampling. ​
  • While slug issues have not been as severe this year, UW is monitoring populations weekly across the state with SlugNet. Slug pressure will decrease with increasing temperatures and crop maturity. ​
  • Check moth trap catches in your region with the DATCP Pest Survey. Sign up for insect pest alerts specific to your region. ​
  • Routine scouting in corn to watch for: true armyworm, stalk borer, and European corn borer. ​
  • Alfalfa weevil populations are coming to an end. Potato leafhopper numbers are increasing; keep an eye on populations the next several weeks. ​
  • Use the VDIFN model to see risk in your region for several economically important pests. ​
  • Scout for tar spot as it has been reported in 5 states close to Wisconsin. Have a plan in place to deal with tar spot if it becomes an issue.
  • Be vigilant for white mold in soybean as plants begin to flower and see risk forecast here.
• Forage Management ​ 
  • Alfalfa stands are at or nearing second harvest in Southern Wisconsin. Scout for potato leafhopper.
  • Consider annual forage options depending on your situation and forage goals.
• Small Grains​ 
  • Fusarium Head Blight risk is high with recent weather conditions; however, much of the wheat is past appropriate growth stage to apply a fungicide. Consider spraying fungicide, especially to susceptible varieties if your wheat has yet to reach Feekes 10.5.1. Scab alerts and risk forecast can be found here.
• Specialty crops- Fruit​
  • General
    • Wisconsin fruit growers can reference the Midwest Fruit Pest Management Guide (MFPMG) for a list of registered products and recommended best practices. View the MFPMG Online or order a hard copy here: MFPMG Hard Copy.
    • Make sure newly planted fruit crops are getting enough water in this heat. Without irrigation, growth can stall during establishment. Irrigation frequency depends on soil type—sandy soils need water daily or every two days, while heavier soils like silt or clay can be watered less often by applying several days’ worth of water at once.
  • Apples​
    • Apple growers should continue monitoring degree-day (base 50℉) accumulation for Codling moth. Second generation larvae will typically emerge at ~1250 degree-days (base 50℉) from the biofix date. Ensure to refresh traps/lures and continue monitoring weekly.​
    • Apple maggot was captured in southern WI. Growers can use red sphere traps to monitor populations and establish a biofix date.
    • Apple and grape growers can reference the NEWA weather station network to monitor for disease infection periods in their area. Check out your nearest weather station: NEWA Weather Station Network (Cornell).
    • Woolly apple aphid has been observed in southern WI. Check for white “cottony” appearing tufts where leaf petioles meet branches.
    • Check out the WI DATCP Orchard Insect Pest Bulletin for more information on current insect trap captures across the state.
  • Grapes​
    • Overview of grape insect/mite monitoring and management: Grape Insects and Mite Pests, 2024 Field Season (Cornell, 2024).
    • Downy mildew foliar symptoms (“oil-stains”) have been observed in West Madison. Scout for pale-yellow lesions on the tops of leaves and white downy growth on the underside of leaves.
    • Apple and grape growers can reference the NEWA weather station network to monitor for disease infection periods in their area. Check out your nearest weather station: NEWA Weather Station Network (Cornell).
• Specialty Crops- Vegetables​
  • Pests​
    • Squash vine borer moth activity is now high in central WI and northern WI can expect to see high levels of activity in the next week. Monitor for these orange and black moths that are active during the day. If you use insecticides, the timing of treatment is key. Treatment must occur when larva are hatching but before they enter stems where they are well protected. More information on organic control methods can be found here.
    • Squash bug eggs are being laid on developing squash and pumpkin plants. Early detection is key! Regularly scout stems and the underside of leaves and depending on your scale either crush egg clusters or if chemical control in necessary, make sure to target the young nymphs that are most susceptible to chemical control. Visit the commercial vegetable production guide for control options. Organic options can be found here. 
    • Scout for cabbage loopers, diamondback moths, and imported cabbage worms as risk is now high across most of the state. ​
    • Continue monitoring for aster leafhoppers which transmit aster yellows to a wide variety of crops. The best way to control aster yellows is by controlling the leafhoppers. Use the aster yellows index (page 19) in the Commercial Vegetable Production guide to help determine when to spray. You can also sign up for text alerts from Michigan State University on infectivity rates from their trapping network. Reports out of Michigan indicate elevated infectivity levels so far this year.
    • Continue monitoring for potato leafhopper, a pest of snap beans and potatoes, either with sweep nets or visually inspecting the underside of leaves.
  • Diseases​
    • The recent hot and wet weather are prime conditions for many diseases to develop.
    • Black rot of brassicas prefers temps over 77°F and high humidity. The bacteria is easily spread by water and enters the leave either through natural openings along the leaf edge or through injuries caused by insects or equipment.​
    • Early detection of alternaria leaf blight of cucurbits will help you control this disease before major damage occurs. Symptoms start as small, water-soaked lesions that can develop concentric rings. The fungus can survive on plant debris for up to two years so be sure to remove and destroy any infected plant tissue at the end of the season.​
    • Alternaria leaf blight can sometimes be confused with anthracnose and angular leaf spot which thrive in similar conditions. Angular leaf spot can be distinguished by angular lesions often confined by veins and the whitish liquid that forms on the underside of leaves when wet and forms a crust when dry. The most distinguishing symptom of Anthracnose is the dark, sunken lesions on fruit that have salmon-colored spores under damp conditions.​
    • Early blight risk is high in southern and central WI and moderate in the north. Early blight infects tomatoes, potatoes, eggplants, and peppers. Prevention is key and includes limiting periods of leaf wetness (when possible!) and increasing air flow through pruning. One way to distinguish this from other diseases is the larger lesions will have concentric rings like a bullseye.
    • Another disease of peppers and tomatoes that likes hot and humid conditions is bacterial spot. Both fruits and leaves can be affected. To prevent the spread of disease, only work in these crops when leaves are dry and sanitize pruners often.
    • Downy mildew has now been confirmed on cucumbers in 4 Michigan counties.

If you would like to obtain a PowerPoint copy of this report, please email rue.genger@wisc.edu.