Current Wisconsin weather and climate conditions

• Summertime warmth remained over the state last week, with multiple days in the 80’s. A large portion of WI was 8-10°F above normal as some locations had days that approached 90°F.
• Multiple days of measurable rainfall last week brought an inch or more of precipitation across most of WI. Totals ranged from less than 0.5” in the south and NW; to over 3” in pockets in the central, west-central, and far north counties.

Impact

• Topsoil moisture at most Wisconet research farm stations were at or above levels from last week due to rainfall. The latest NASS report  indicates a very minor increase (1%) in the percentage of agricultural soils that are dry to very dry.
• Drought severity and coverage remain relatively unchanged in WI despite the recent dryness.
• Corn and soybean crops are near maturity or at maturity in most WI fields, with conditions remaining good to excellent for most (NASS). Winter wheat is beginning to emerge as the fourth cutting of alfalfa is nearing completion.

Outlook for Wisconsin weather and climate

• Little to no precip is expected over the next 7 days.
• Climate probabilities for early October indicate a strong likelihood (70-80% chance) to be warmer than normal, with a mixed bag for precipitation.
• The outlooks for the month of October (updated 9/18) do not show any strong indications of above or below normal conditions.

Agronomic considerations

• Field Work and Conditions
  • Corn and soybean grain harvest has begun on a limited scale.
• 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 ​ 
  • The DATCP Pest Survey has concluded for the season as pest pressure is winding down.
  • 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.
• 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 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.
  • Consider planting a cover crop after silage. This will aid in reducing soil erosion going into winter.
• 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
    • Reminder: Always read and follow directions on the label and keep in mind pre-harvest intervals (PHI) as we move through harvest!
    • Sun scald and southwest injury to trunks and branches have been observed across many orchards and vineyards this summer, likely due to wide variations in winter temperatures that can cause trunk and branch cracking. Growers may consider flagging trees and branches while harvesting, then return this winter to prune out impacted branches and take a closer look at injury.
    • Fruit sunburn continues to be observed across many fruit crops in southern WI. Consider removing this fruit while out picking 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.
    • WI fruit growers can reference the Midwest Fruit Pest Management Guide (MFPMG) for a list of registered products and recommended best practices. (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.
  • 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).
    • Apple growers should continue monitoring pheromone traps and degree-day (base 50℉) accumulation for Codling moth through harvest.
    • 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 and wine grape harvest is just about wrapped up at West Madison Ag. Research Station. Check out last week’s 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.
    • Grape growers dealing with uneven ripening may reference this 2024 WI Fruit News article: Understanding and Addressing Uneven Ripening in Grapes.
    • Downy mildew may impact grape quality at harvest. Read more about signs/symptoms and management in this 2024 WI Fruit News article on late-season downy mildew
  • Berries
    • Grape and berry growers monitoring spotted wing drosophila should continue checking and refreshing traps weekly through harvest.
• Specialty Crops- Vegetables​
  • General
    • As crops finish up for the season, there is still time to establish winter rye across the state as well as winter wheat and winter barley in southern WI. Use the Midwest Cover Crop Council’s cover crop selector tool to determine the latest planting date for each species in your specific county.
  • Pests
    • Have you struggled with asparagus beetles in the past? Once ferns are completely brown, it is recommended to either chop or mow them and then remove and compost elsewhere when possible. This will prevent the beetles from overwintering in your field.
    • 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 recent dry weather means that the risk of damage from western flower thrips is high. Thrips can be difficult to control as of 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.
    • 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​
    • This year’s moisture stress combined with high temperatures can increase the risk of potato tuber diseases 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.
    • Potato yield and tuber size can be negatively affected by silver scurf and black dot. These diseases can both occur on the same plant and are difficult to distinguish. An important management strategy for both diseases include limiting the amount of time between vine kill and harvesting as tubers are at greater risk the longer they remain in warm, moist soil. Read Dr. Amanda Gevens’ newsletter for more information on the life cycle and management of both diseases.
    • When possible, harvest mature winter squash rather than let it sit in the field. As vines die back, squash bugs will be more attracted to the fruit. The damage caused by their feeding can provide entry points for diseases. Additionally, during rain events, fruits can become infected by the soil dwelling pathogens fusarium and phytophthora.
    • Scout for symptoms of alternaria and cercospora on carrot leaves. These diseases can be difficult to tell apart as both cause brown lesions often surrounded by a yellow halo. One distinguishing factor can be the timing of infection. Cercospora often occurs on young, rapidly growing plants while alternaria often occurs on older plants although can occur on young plants as well. Both can cause yield loss due to petioles breaking off during mechanical harvest is disease pressure is high.
    • Recent conditions with warm days, cool nights, and heavy dew in the morning are right for the formation of alternaria in brassicas. Leaf spots are grey or black in color and have concentric rings as they enlarge. It 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. Management options include planting resistant varieties, removing alternative hosts such as sheperd’s purse and field mustard, and fungicides. 

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