Current Wisconsin weather and climate conditions

• The majority of WI received less than an inch of precip last week, with higher totals in the west. The last 2 weeks in the state have been relatively dry, with most of the state receiving less than 70% of normal precip for mid-to-late August.
• Fall-like weather has been in place over the last several days, with lows dipping into the 40s on several nights and average temps running below normal statewide. Conditions have been near normal across most of WI over the past 30 days.

Impact

• After a relatively dry week, soil moisture is estimated to be near normal for most of the state, with dryness increasing in the far NW. Wisconet research farm stations show decreases in 4” soil moisture from last week at most sites.
• Drought remains non-existent in the state, with a minimal increase in D0 coverage (western Douglas County).
• Corn and soybean progress are running slightly behind normal pace, with alfalfa cutting running several days ahead of normal. Crop condition reports indicate 83-84% of corn and soybeans are rated good to excellent (NASS).

Outlook for Wisconsin weather and climate

• Precip for the next 7 days is most likely in the north, with some chances for overnight lows to get into the 30’s (NWS tool).
• Climate probabilities for mid-September show a lean towards above-normal temperatures for all of WI (40-50% chance).
• The outlooks for the month of September (updated 8/31) are uncertain for temps and precip with equal chances.

Agronomic considerations

• Field Work and Conditions
  • Avoid trafficking fields in moist conditions to prevent compaction.
  • As fall air sets in, check your local Frost Freeze Decision Support Page.
• 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 ​ 
  • Check moth trap catches in your region with the DATCP Pest Survey. Sign up for insect pest alerts specific to your region.
  • Scout for soybean aphid and soybean gall midge (SGM not presently in Wisconsin; however, the pest has been located in nearby states).
  • Monitor for corn earworm through mid-September. 
  • Southern Rust has been reported across the state. Heavy disease pressure can cause premature dry down, reduced kernel weight, and lower yield potential.  
  • Fall armyworm egg-laying may be occurring in late-planted corn fields. Also be vigilant of activity in alfalfa fields. Pay attention to trap catches through mid-September. 
• Forage Management ​ 
  • Use the alfalfa cutting tool to plan remaining alfalfa harvests for stand persistence.
  • Consider in-field management strategies to reduce mycotoxins in silage. Begin sampling and estimating moisture as silage matures. Read corn silage harvest management considerations.
  • Silage chopping has begun in the southern region of the state. Foliar disease presence can make silage harvest timing critical. Read these considerations for managing disease at chopping.
  • Explore the new Corn Silage Dry Down Monitoring Tool to see what samples are measuring at in your region.
• Small Grains​ 
  • The window to plant winter wheat is approaching (September 20-October 10). Review planting and management guidelines as well as Top 9 suggestions for 2025 establishment.
  • Consider planting a cover crop after small grain harvest. Review Cover Crops 101 for a list of viable species and seeding recommendations. Cover crops can also be an opportunity for grazing.
• Specialty crops- Fruit​
  • General
    • Reminder: Always read and follow directions on the label and keep in mind pre-harvest intervals (PHI) as we move through harvest!
    • Growers who experienced heavy rainfall and flooding in the past month should review best practices for identifying and preventing root rots: Rainfall and root rots in commercial fruit operations (University of Connecticut)
    • 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 can cause trunk and branch damage.
    • Fruit sunburn has been observed across many fruit crops in southern WI. Consider removing this fruit to prevent other pests attracted to the volatiles (scent).
    • Sanitation: remove and destroy (chop/compost) fallen fruit ~weekly to prevent any internally developing larvae from reaching maturity, and to limit the spread of disease.
    • 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.
  • Apples​
    • 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).
    • Sooty blotch and flyspeck continues to be observed in Southern WI, pushed along by warm, humid conditions. Continue monitoring NEWA models.
    • Apple growers should continue monitoring pheromone traps and degree-day (base 50℉) accumulation for Codling moth.
    • Apple maggot pressure is variable across the state. Growers should continue to use red sphere traps to monitor populations.
    • Check out the WI DATCP Orchard Insect Pest Bulletin for more information on current insect trap captures across the state.
  • Grapes​
    • Table grape harvest has begun, with wine grapes soon to follow at West Madison Ag. Research Station. Check out last weeks WI Fruit Crop Scouting Report for updates on grape maturity testing.
    • Black rot and fruit rot symptoms have been 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.
    • Overview of grape insect/mite monitoring and management: Grape Insects and Mite Pests, 2024 Field Season (Cornell, 2024).
  • Berries
    • Grape and berry growers monitoring spotted wing drosophila should continue checking and refreshing traps weekly through harvest.
• Specialty Crops- Vegetables​
  • Pests
    • The recent dry weather means that the risk of damage from western flower thrips is high across much of the state. Thrips can be difficult to control as of result of their small size and their tendency to hide. Control options can be found here.
    • While the peak of the second generation of adult Colorado potato beetles is occurring in central and northern WI, larva populations are decreasing. Remember that the impact of insecticides on adults is minimal. Detailed management info can be found here.
    • The second generation of European corn borer adults are very active across central and northern WI. Scout for egg masses in beans, eggplant, peppers, potato, and sweet corn. Economic thresholds and management options for these crops can be found here.
    • The cooler weather has slowed the flight of corn earworm moths. However, the large number of trap catches through late August means that sweet corn growers should continue to monitor late planted corn with green silks. Sweet corn is vulnerable from row-tassel to 100% silk. Insecticides must be present on vulnerable silks when eggs hatch. Organic control options can be found here, and conventional insecticide options can be found in the commercial vegetable production guide.
    • The second generation of adult crucifer flea beetles are active in northern WI.  Yellow sticky cards can be used to help determine their population. Treatment is recommended when 10-20% of a stand shows damage. Populations can be spotty across a field so spot treatment can be very effective.
  • Diseases​
    • Southern corn rust has been positively identified in over 20 counties in WI. Symptoms include raised bumps called pustules that will stain your hand if rubbed off. These pustules are often on the upper leaf surface. Southern rust can be confused with several other conditions. This resource from the Crop Protection Network can help with id.
    • Angular leaf spot has been commonly diagnosed on cucurbits in recent weeks. Symptoms may be confused with downy mildew as lesions are angular and bound by leaf veins. A few ways to help distinguish them is that angular leaf spot often starts as small water soaked lesions on the underside of leaves, the lesions will turn white and papery as they age, and under humid conditions milky colored ooze may form on the spots. While the recent dry weather will help reduce the spread of this disease, the bacteria can survive on plant debris for up to two years. Either remove and destroy or till in infected plant tissue at the end of the season.
    • Phytophthora crown and fruit rot can infect a large range of fruiting crops including cucurbits and solanaceous crops (tomato, pepper, eggplant). Crown rot will cause the entire plant to collapse and die in a short period of time. Vines will turn brown and appear water soaked before collapsing. Symptoms on fruit often appear on the underside of fruit where it is in contact with the ground, but they can also start around the stem if the infection is systemic. Lesions appear water soaked & under humid conditions, sporangia may form that are similar in appearance to yeast. Water management is one of the best cultural controls for this disease. Other management options can be found here.
    • Anthracnose of cucurbits can infect all above ground plant tissue. Symptoms vary based on which cucurbit is infected. On melons and cucumber lesions are brown, irregularly shaped, and often have a yellow halo. On watermelons, the lesions are darker and smaller. Stem infections on melon will often secrete a red colored gum. Fruit lesions are black and sunken and salmon-colored spores will form during high humidity. Winter squash and pumpkins are not often infected.  
    • The first symptoms of brassica alternaria are pin sized black specks on the leaves or stem. As the lesions expand, they will form concentric rings and black, sooty spores form during periods of high humidity. Sources of inoculum include infected plant debris and brassica weeds. It is spread by wind, rain, and insects like flea beetles.

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