in many Illinois corn fields. The virulent pathogen- -the fungus that causes southern 

 corn leaf blight- -is already present. Now the weather conditions --frequent rains, high 

 humidity, and warm temperatures- -are right for fungus growth. 



Check susceptible fields frequently for new lesions that may appear on leaves, leaf 

 sheaths, stalks, ears, and husks to determine whether spraying is warranted. So far, 

 few ear infections have been found. Leaf, sheath, and stalk infections are more com- 

 mon in most areas. 



Infections, including some ear infections, appear to be increasing in the parts of 

 southeastern Illinois that received rain earlier- -Gallatin, Richland, White, Wabash, 

 and the surrounding counties. Physoderma brown spot, another corn disease, also ap- 

 pears to be spreading on certain hybrids in that area. This disease has not caused 

 serious economic loss in the past. 



Plant pathologists in Indiana and Iowa report an increase in the number of spores trap- 

 ped during the past two weeks --indicating that spores are beginning to move through the 

 air and may spread infections from field to field. The Indiana pathologists also re- 

 port an increase in the number of lesions appearing on corn plants. There has been 

 only a slight increase in the number of spores caught in spore traps at the Dixon 

 Springs Agricultural Center near Simpson and on the Urbana- Champaign Campus. 



So far, most severe blight infections are limited to localized areas where heavy con- 

 centrations of susceptible T cytoplasm seed were planted, where volunteer corn or dis- 

 eased debris remained in fields, or where farmers shelled or loaded diseased 1970 corn 

 from cribs. 



READ THE LABEL AND FOLLOW ALL PRECAUTIONS 



This weekly report was prepared as follows : 



INSECTS: H.B. Petty, Steve Moore, Roscoe Randell , Don Kuhlman, and Tim Cooley , Col- 

 lege of Agriculture, University of Illinois at U rh ana- Champaign , and the Illinois 

 Natural History Survey. 



WEEDS: Ellery Knake and Marshal McGlamery , Department of Agronomy. 



PLANT DISEASES: M.C. Shurtleff and Ed Burns, Department of Plant Pathology. 



AG COMMUNICATIONS: Ray Noodis . 



The information for this report was gathered by these people, staff members, county 

 Extension advisers, and others, in cooperation the the USDA Agricultural Research 

 Service, Plant Pest Control Branch. 



