Corn Disease Risk Maps

For period of Aug 6 – Sept 5, Date of Issue: August 7, 2022 
DEKALB® corn field at late season
Delaro Complete
CLICK ON DISEASE FOR RISK FORECAST
One-Month Weather Outlook​

Temperatures next week will be normal or cooler, but then move higher in the following week, and remain above normal during the following two weeks.  Normal to above normal rainfall amounts are predicted for the Ohio River Valley, but below normal precipitation is expected elsewhere.   

​Northern Leaf Blight Risk Summary ​

The risk level of northern leaf blight is decreasing, but remains moderate for much of the Corn Belt.    

​Next two-week risk interpretation  ​

During the next two weeks conditions are moderately favorable for NCLB across the Midwest.  In at-risk areas scout susceptible hybrids, especially in fields with a history of this disease in prior years.  Consider spraying an effective fungicide if disease symptoms are found on the ear leaf or higher.

ONE-MONTH RISK MAP
One-Month Weather Outlook

Temperatures next week will be normal or cooler, but then move higher in the following week, and remain above normal during the succeeding two weeks.  Normal to above normal rainfall amounts are predicted for the Ohio River Valley, but below normal precipitation is expected elsewhere.        

Gray Leaf Spot Risk Summary

The risk of gray leaf spot continues to increase, especially east of the Mississippi River.

Next 2-week risk interpretation 

During the next two weeks conditions are favorable for the development of gray leaf spot for much of the Corn Belt.  Most of the southeast section of the forecast map is at high risk.  Consider spraying a fungicide if lesions are observed above the ear leaf and the corn has not reached growth stage R5.  

Gray Leaf Spot - On Leaf
ONE-MONTH RISK MAP
One-Month Weather Outlook

Temperatures next week will be normal or cooler, but then move higher in the following week, and remain above normal during the following two weeks.  Normal to above normal rainfall amounts are predicted for the Ohio River Valley, but below normal precipitation is expected elsewhere.   

Southern Rust Risk Summary

Southern corn rust has remained limited to the southwest portion of the forecast region.         

Next 2-week risk interpretation 

Over the next two weeks conditions remain favorable or moderately favorable for tar spot in most of the areas where tar spot was observed in prior seasons.  Scout fields in at-risk areas and consider spraying an effective fungicide if symptoms are observed.  Irrigated fields are at higher risk.  

An example of Southern Rust on corn leaves.
ONE-MONTH RISK MAP
One-Month Weather Outlook

For the next two weeks and continuing through the next 30 days temperatures are expected to be above normal for the entire region.  Less-than-normal precipitation will fall west of the Mississippi River with normal amounts to the east and increasing toward the coast.  

Corn Tar Spot Risk Summary

The risk is moderate to high for most of the areas that have experienced tar spot in previous seasons.         

Next two-week risk interpretation 

Over the next two weeks conditions remain favorable or moderately favorable for tar spot in most of the areas where tar spot was observed in prior seasons.  Scout fields in at-risk areas and consider spraying an effective fungicide if symptoms are observed.  No midwestern hybrids have been observed to be fully tolerant to the disease.  Irrigated fields are at higher risk.         

Tar spot of corn
ONE-MONTH RISK MAP
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