Current Wisconsin weather and climate conditions

• Summertime warmth remained over the state last week, with temps that were 12°F or more above normal. Multiple days topped 80°F statewide, with some in the SW topping 80°F on all days last week.
• Rainfall totals were relatively low last week, with most receiving less than a half inch. Totals were highest in the west-central region, while some in the SW have received less than 1” since early September.

Impact

• Topsoil moisture at most Wisconet research farm stations were near or below last week’s levels due to lower rainfall totals for most. Satellite-based soil moisture products indicate increasing dryness statewide, closer to normal in the west.
• The state is no longer drought-free with the addition of D1 in the NW and far S, along with a >30% increase in D0 coverage.
• NASS crop progress reports are unavailable this week due to the federal government shutdown.

Outlook for Wisconsin weather and climate

• The best chances for precip over the next 7 days is in the northwest, with multiple chances for rain into early next week.
• Climate probabilities for mid-to-late October indicate a slight lean towards above normal temps (40-50% chance), with precip leaning above normal in the west.
• The outlooks for the month of October (updated 9/30) indicate a strong likelihood (60-70% chance) for above normal temps. Precip is uncertain.

Agronomic considerations

• Field Work and Conditions
  • The lack of rainfall has been challenging for cover crop establishment.
  • After crop harvest is an ideal time to take soil samples and plan ahead for next year’s crop nutrient needs.
  • Use the WI Frost Freeze Decision Page as overnight temperatures are dropping.
• 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.
  • Fall is a great time to have manure samples analyzed for nutrient content before spreading. Here is a list of Wisconsin certified labs.
  • As you conduct fall spreading, keeping field records is important to estimate nutrient credits for next year’s crop and avoid over-application.  A2809 can provide guidance on these nutrient estimates.   
• Pest Management ​ 
  • Southern Rust has been reported across the state. Heavy disease pressure can cause premature dry down, reduced kernel weight, and lower yield potential.
  • In order to prevent weed seed spread from field to field, combine cleaning is essential for reducing seed travel between fields. There have also been many combine fires this year. Keeping combines clean will help minimize risk. ​
• Forage Management ​ 
  • Silo gas has been present around a variety of silage storage structures this year. Be aware of the dangers of silo gas and stay away from recently filled structures, particularly when the weather is calm with no wind.
  • Use the alfalfa cutting tool if you plan to make a final cut in October to manage for stand persistence.
  • Begin sampling and estimating moisture as silage matures. Read corn silage harvest management considerations.
  • 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 as well as read regional reports.
  • Consider planting a cover crop after silage. This will aid in reducing soil erosion going into winter.
  • Avoid immediately grazing frost-damaged sorghum as the risk of prussic acid toxicity is high.
• Small Grains​ 
  • The window to plant winter wheat is here (September 20-October 10). Review planting and management guidelines as well as Top 9 suggestions for 2025 establishment.
• Specialty crops- Fruit​
  • General
    • Fall Sanitation: Clean up weeds around trees and vines, mow aisles to allow for better light penetration to aid in decomposition of leaf/plant material.
    • Fall Sanitation: After leaf drop, chop, compost, remove or burn (where permitted) fallen leaf and plant material to to limit potential for disease inoculum and any overwintering pests.
    • 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.
    • Brown marmorated stink bug has been observed at West Madison. Keep an eye out for large populations. Hosts include apple, cherry, peach, pear, raspberry, and cranberry.
    • Reminder: Always read and follow directions on the label and keep in mind pre-harvest intervals (PHI) as we move through harvest!
  • 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).
  • Grapes​
    • Table and wine grape harvest is completed at West Madison Ag. Research Station and the Peninsular Ag. Research Station. Check out the September 24 WI Fruit Crop Scouting Report for the most recent update on grape maturity testing.
    • Grape growers dealing with uneven ripening may reference this 2024 WI Fruit News article: Understanding and Addressing Uneven Ripening in Grapes.
• Specialty Crops- Vegetables​
  • General
    •  As crops finish up for the season, there is still time to establish a winter rye cover crop across the state. Rye has many potential benefits including prevention of erosion and holding nutrients in the soil, but keep in mind that cover crop benefits are strongly related to biomass. Knowing the planting window for your county can help you predict the amount of biomass and thus the likely cover crop benefits. If you are planting towards the end of the window, it is recommended to increase seeding rate to achieve more biomass. More management suggestions can be found here.
    • Pest management for next year’s crops starts this fall as many insects and diseases overwinter on crop residue. Residue management (either removing or tilling in residue) can help reduce next year’s pest and disease pressure. Pests include asparagus beetles, crucifer flea beetles, imported cabbage worms, squash bugs, onion maggots and more. Diseases include angular leaf spot, early blight, stemphylium leaf blight, brassica alternaria, and phytophthora blight of cucurbits. Additional info can be found here.
  • Pests
    • If you are noticing distorted & stunted leaves or russeting on your high tunnel peppers, you might have broad mites or cyclamen mites. These mites also feed on a wide range of flowers including dahlias and snapdragons. They can be difficult to control as they hide in developing buds and the distorted leaves. Management options include releasing predatory mites if pest populations are not too high and chemical controls.   
    • Be on the lookout for cabbage aphids and green peach aphids in fall brassicas & greens. They can be difficult to see so look for yellowing & wilting leaves, deformed heads, & drops of honeydew aka aphid poop which is a thick, sticky liquid. Their populations can explode quickly in the fall as reproduction rates actually increase in cool temps (50-68°F).
    • The risk of damage from western flower thrips remains high across northern WI and along lake Michigan. Thrips can be difficult to control as a result of their small size and their tendency to hide. However, there are many tactics that can be combined for better management. Options include promoting more beneficial insects such as minute pirate bugs, using reflective mulch, and chemical control. More details on control options can be found here.
  • Diseases​
    • Brassica alternaria was recently identified in Dane County. Leaf spots are grey or black in color and have concentric rings as they enlarge. Spores can be spread by rain, wind, and insects like flea beetles. Although due to their larger size, spores cannot travel as far on the wind as downy or powdery mildew spores. If your brassicas are infected, be sure to remove or till in the infected plant tissue to reduce overwintering sites in your field. Other management options include planting resistant varieties, removing alternative hosts such as shepherd’s purse and field mustard, and fungicides. 
    • While powdery mildew will not infect the fruit of pumpkins, the stems can be infected resulting in shriveled and weak stems for Halloween pumpkins. It is recommended to cut the stems even if the pumpkins are not fully mature as they will ripen off the vine. Additionally, if vines die back from powdery mildew, the fruit can be susceptible to sunscald so be sure to monitor your crop in the field.
    • This year’s moisture stress combined with high temperatures can increase the risk of potato tuber diseases during this time of year. Test dig potatoes to look for pink eye, enlarged lenticels, and other physiological conditions. If you notice any of these abnormalities, make sure you are carefully monitoring for disease in storage. Diseases to be monitoring for include pink rot, late blight, pythium leak, and bacterial soft rot. More information on symptoms and management options can be found here.

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