Current Wisconsin weather and climate conditions

• Summertime warmth remained over the state last week, with average highs in the 70s to 80s. A large portion of WI was 4-8°F above normal.
• Rainfall was sparse over the last week, with most of the week’s rain falling the early hours of 9/23. 7-day totals were largely less than 0.1”.

Impact

• Topsoil moisture at most Wisconet research farm stations were below last week’s levels due to little-to-no rainfall. The latest NASS report indicates a 3-4% increase in the percentage of agricultural soils that are dry to very dry.
• Wisconsin remains drought free, but abnormal dryness (D0) expanded to now cover >35% of the state (north, SW).
• Corn and soybean crops are near maturity or at maturity in most WI fields, with conditions remaining good to excellent for most (NASS). Soybean and corn harvest have begun, with corn silage harvest at two-thirds complete. Winter wheat is beginning to emerge as the fourth cutting of alfalfa is nearing completion.

Outlook for Wisconsin weather and climate

• The best chances for precip over the next 7 days in the south/southwest, and lowest in the northwest.
• Climate probabilities for mid-October indicate an increased likelihood (50-60% chance) to be warmer than normal, with a lean towards above normal precipitation.
• 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
  • Corn and soybean grain harvest has begun, driven by dry 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.
• 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 if you plan to make a final cut in October to manage 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 officially completed at West Madison Research Station, harvesting Petite Pearl, La Crescent and Frontenac this week. 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.
    • 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 information 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​
    • 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.
    • 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 if disease pressure is high.
    • Cercospora can also cause losses during mechanical harvest of table beet. While we have received little rain in recent weeks, the dewy mornings provide favorable conditions for this disease. Management options include control of alternative weed hosts (lambsquarters and pigweed), fungicides, and minimizing leaf wetness with overhead irrigation.

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