June 18th, 2026 Weather Outlook

Key Points

Recent Conditions

• Temperatures were 3-6°F above normal across most of the state, with the eastern and northern counties being the most above normal. Growing degree day accumulation (since May 1 and May 15) is running ahead of normal pace. 
• Precipitation totals were highest in southern and central counties last week (2-4”), totals that were 175-300% of normal. Most received at least a half inch of rain. 

Impact

• Most Wisconet research farm stations gained moisture in the top 4 inches of soil due to rainfall totals of 1-3” of rain last week for most. 
• Satellite-based soil moisture estimates indicate widespread improvements in soil moisture, with most of the state estimated to have near-normal soil moisture in the top 1 meter. 
• Recent rainfall has helped to reduce drought coverage in the state. D1 coverage dropped by 10% compared to last week’s report. 
• Emergence is nearing completion (>90%) for both corn and soybeans. With adequate soil moisture for most Wisconsin fields, row crops in the state are primarily in good to excellent condition. 

Outlook

• Rain is most likely in the southern tier of counties over the next week, with multiple rain chances statewide. 
• The outlook for the June-July transition indicates near-normal temperatures and above-normal precipitation for most of the state. 
• The outlook for July does not offer any strong indications for temperature and precipitation deviations currently. 
• Late summer through early fall (July-Sept) may be cooler-than-normal in southern and central counties (33-40% odds), with precipitation leaning towards below normal for most of the state. 

Agronomic, Fruit and Vegetable Considerations

Field Conditions

•  June is the time for pre-sidedress nitrate soil sampling. See guidelines for PSNT sampling.
• Thunderstorms have brought hail to areas of the state. Read more about hail damage and crop impacts here.  

Forage Management

• First crop alfalfa harvest is nearing completion in Northern WI. Consider using a PEAQ (Predictive Equations for Alfalfa Quality) stick to estimate relative feed value as you decide when to make each cut. 

Pest Management

• Scout fields to note what weed species are emerging or have escaped herbicide application.  
• Early planted soybeans are reaching reproductive stages. Revisit POST herbicide labels for timing considerations. Glufosinate must be applied before the R1 stage and Enlist One can be applied through the R1 stage.  
• Look for true armyworm larvae in corn (especially around V5), grass pasture, and small grains.  
• Western bean cutworm trapping has begun for the season. Check DATCP trap catches.  
• Scout emerging corn until V5 for signs of cutworm feeding.  
• Continue scouting for alfalfa weevil larva, mostly in the northern half of WI. Weevil larvae have the greatest impact (quality and yield) on first and second alfalfa cuts.  
• SlugNet is trapping again in 2026! Review weekly trap catches across the state. Observe fields (especially fields with reduced tillage and cover crops) for any signs of slug damage.  
• Continue to scout corn and soybean fields for disease. While disease in these crops has been of low concern so far, recent precipitation could change conditions to be more favorable.  

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. 

Small Grains

• Scout small grains for signs of disease. This includes powdery mildew and stripe rust, especially in susceptible varieties. Use the Crop Risk Tool and Fusarium Risk Tool for risk assessment for Fusarium Head Blight. FHB risk has increased.  
• Staging small grain growth is important for fungicide timing as diseases are emerging. Winter wheat in the southern half of the stat is past the window to spray fungicide. Those in the central and northern parts of the state may still have an opportunity, if warranted. Review growth stages here.  

Fruit Considerations- General

• Wisconsin fruit growers can reference the bi-weekly Wisconsin Fruit News for the most recent, in-depth updates on fruit production, including disease and insect management. 
• 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). Check out your nearest weather station: NEWA Weather Station Network (Cornell). 
• Grape growers may reference Dr. Amaya Atucha’s most recent article on petiole sampling in cold hardy grapes. 
• Wisconsin fruit growers can reference the Midwest Fruit Pest Management Guide for a list of registered products and recommended best practices. View the MFPMG Online. 

Fruit Considerations- Disease

• Apple scab fruit lesions have been observed in Southern WI, likely pushed along by recent rains. Continue scouting scab susceptible varieties. A reminder that protectants will typically wash off after ~1inch of rain. 
• Strawberry growers may reference the most recent Wisconsin Fruit News article on Strawberry Disease Concerns Following Heavy Rains During Harvest by Dr. Leslie Holland. 

Fruit Considerations- Insects

• Apple growers should continue monitoring degree-day (base 50℉) accumulation for Codling moth. First generation larvae will emerge after ~250 degree-days (base 50℉) have accumulated from the biofix date. Second generation larvae will typically emerge at ~1250 degree-days (base 50℉) from the biofix date. 
• Apple growers should keep track of degree-day (base 50℉) accumulation from petal fall to determine the end of plum curculio movement into the orchard. Plum curculio will typically cease movement into the orchard after ~308 degree-days (base 50℉) have accumulated from the petal fall date. 

Vegetable Considerations- General

• Remove garlic scapes to maximize bulb size. Research has shown that failure to remove garlic scapes can reduce bulb size by as much as 48%. Scapes can be removed as soon as they emerge or if you have a market for scapes, once they are fully coiled. Removing scapes at full coil has a minor impact on yield, research has shown a 9% reduction, but make up for this loss with the demand from consumers. If hand removal is not practical, research has shown that letting the scapes grow longer (30-40cm) and then cutting with a sickle bar mower reduces damage to leaves and minimizes impacts on yield.  
• It is a great time to consider summer cover crops before planting fall crops. Summer cover crop options include buckwheat, cowpea, and sorghum sudangrass. Check out these videos from UW Madison Extension and Iowa State Extension to learn more about what might work on your farm. Purdue also has a great article on this topic.  
• While favorable weather for late blight has occurred since approximately 50% of potato crops have emerged, we still have not reached that point that preventative applications are necessary.  

Vegetable Considerations- Disease

• Cucumber downy mildew spores have been detected in 3 eastern and southeastern counties in Michigan. However, no reports of disease outbreaks have been reported in Michigan or Wisconsin.  
• Recent weather conditions, wet and cool, are favorable for halo blight in green beans. Monitor leaves for symptoms which first appear as water-soaked lesions on the underside of leaves. As the disease progresses, the lesions become red to brown in color and are surrounded by a yellow-green halo. Symptoms resemble downy mildew however they lack the gray sporulation on the underside of leaves. Pods can also become infected, and symptoms are water-soaked lesions. This disease is typically not widespread however, there is a confirmed report in Iowa. Management information and comparison between bacterial disease in green beans can be found here.  
• Monitor brassicas for symptoms of black rot which include yellow blotches that start on leaf margins and spread in a v- shaped pattern into the leaf. Veins will also appear brown or black when held up to a light. One of the best management strategies during the season is avoiding working in fields when foliage is wet.  

Vegetable Considerations- Insects

• Squash vine borer risk is high in southern WI and will be increasing in central WI in the next week. Be on the lookout for adults which are day flying moths. Their abdomens are red to orange in color with black spots. Newly emerged females begin looking for hosts to lay eggs shortly after emerging. Floating row cover during peak adult activity can reduce crop risk although it must be removed during flowering. Chemical control options are limited once larvae move into the plant stem. Effective chemical control requires insecticides to be in place before and during egg laying.  
• Stalk borer risk is high in central WI. Starting in late May the larvae migrate from grassy weeds along field edges into susceptible crops which include tomatoes, potatoes, sweet corn, and beans. Larvae feed on leaves or stalk tunnels, causing irregular holes in the newly unfolding leaves. Control options are limited this time of year. If eggs have already hatched, removing alternative weed hosts can increase the amount that migrate into your crop. For chemical treatment to be effective, treatment must occur before larvae have moved into the crop stem. Therefore, it is very difficult to use chemical controls as their presence is not often noticed until they are already inside the stem and have caused damage. 
• Risk from the second generation of western flower thrips (WFT) is now high in southern WI and will be increasing in central WI over the next week. Early detection is key as control can be very difficult. WFT can spread viruses including tomato spotted wilt virus which can infect tomato, pepper, potato, and eggplant. Symptoms typically start at the top of the plant. Dark brown to black areas form on leaves, stems, and fruit. If plants become infected, rogue them out immediately to reduce the chance of spread. WFT management options include weed management inside and outside of high tunnels, reflective mulch, and insecticides. 
• MSU reports on aster leafhoppers indicate that infectivity levels are currently 6% or less with many at 0%. Sign up for text alerts here to get an idea of how infectivity levels are changing throughout the season. Aster leafhoppers spread aster yellows which can cause significant damage to a range of crops including garlic, lettuce, carrots, and parsley. Control of aster yellows depends on control of the aster leafhopper. Management options include floating row covers, planting resistant cultivars, and insecticides. 
• Monitor beans and potatoes for signs of potato leafhopper damage which include veins turning yellow and leaf curling during early stages and later appears as the characteristic “hopper burn” that leads to the yellowing or browning of leaf tips. Damage occurs most rapidly under hot and dry conditions. Management information and action thresholds can be found here.  
• Continue scouting for Colorado potato beetle. Reports from the Vegetable Crop indicate that “in much of southern Wisconsin, larval populations are well into mid- and later stages of larval development, whereas only early larval stages are present in most fields within central Wisconsin.” Larvicide recommendations can be found here. In northern WI, continue scouting for colonizing adults and egg masses. Control options include perimeter and edge applications.  
• Continue to scout for striped cucumber beetles. Adults feed on foliage and fruit and can spread bacterial wilt which can cause severe losses in cucumber and muskmelon. It is important to scout and, when necessary, control beetles early in the season to reduce risk of spreading this disease. Management options include spraying plants with kaolin clay although this will wash off with rain, floating row cover or high tunnel insect exclusion screens, and soil drenches for larvae.  
• Scout for cabbage looper, imported cabbageworm and diamondback moth eggs and larvae. Plants are most susceptible to damage as young transplants and from early heading to harvest so the management threshold is when 10% of plants are affected. More information on treatment thresholds and management options can be found here. It is best to rely on larvae counts rather than damage or frass (droppings) to determine the level of infestation. Resistance to insecticides is a risk with these pests. Rotate modes of action, choose a selective insecticide when possible, and spot treat or band applications rather than broadcasting.  
• The risk of damage from the second generation of seed corn maggots larvae is high in northern WI, and the third generation is now active in southern WI. Injury is caused exclusively by larvae which feeds on the cotyledons and below ground tissue of seedlings. Management is only effective if done in a preventative manner. Once larval damage is detected, there are no control options. Preventative management options can be found here.  
• Cabbage maggot peak egg laying is now occurring in northern WI. Treatment is primarily preventative. When possible, till in cover crops 2 to 3 weeks before planting to reduce attractiveness. If possible, delay planting to avoid peak activity. Plantings after mid-June generally suffer less damage than early plantings. Floating row covers and diatomaceous earth are also good options during peak activity. To monitor activity in your area, use the Vegetable Disease and Insect Forecasting Network.  
• DATCP continues to report black cutworm moth trap catches. Black cutworm larvae feed on newly emerged crops and prefer direct seeded crops over transplants. Many crops are susceptible to damage including beets, carrots, cucumber, leafy greens, sweet corn and squash. Management options include weed management as females prefer to lay eggs in weedy areas and avoiding the use of green manure in areas where cutworms tend to be a problem. For chemical control to be effective, early detection is key. If chemical treatment is necessary, begin treating at the first signs of cutting and repeat every 7 days until 1000 degree days are reached.  

Temperature Trends

Growing Degree Days (Base 50°F)

Crop Progress and Condition