CORN DISEASES 



Anthracnose . This is seldom found on corn in Illinois. The disease is caused by the 

 fungus Colletotrichum gvamtnioolum , but development is restricted in this state because 

 infection usually requires extremely humid conditions. A diseased sample came from U. 

 of I. Area Agronomist George McKibben's plots near Glendale, Illinois. There, the 

 disease appeared on normal corn in both zero-till and conventional plots. 



Southern corn leaf blight . SCLB caused by both race and race T of Helminthosporivm 

 maydis has been found in research plots in central and southern Illinois. Race 

 had infected normal corn; race T, the Tms corn. In all cases, only trace-level in- 

 fections were found. Lesions occurred only on the lower two or three leaves. 



The infections, however, confirm for the second year our research showing that race 

 can survive winter conditions, at least in southern Illinois; also, that race T 

 can overwinter as far north as central Illinois. Other research shows that race T 

 has overwintered in corn debris in Pennsylvania and Minnesota. 



Dry weather has generally kept SCLB under control this year, and no major problems 

 are expected at this point. No samples of blight on N-cytoplasm com from farmers' 

 fields have been received to date. 



Physoderma brown spot . During 1971, serious problems on white corn in southeastern 

 Illinois were caused by Physoderma maydis . U. of I . research plots on the Scates 

 and Williams farms near Ridgway now show infections --indicating the probable over- 

 wintering of Physoderma. These infections appear to be slightly worse in minimum- 

 tillage than in plowed plots. Helminthosporium maydis has also survived in this 

 area, and confounds the symptoms; however, dry weather has generally checked the 

 development of brown spot. 



The resistance of 135 hybrids and inbreds to Physoderma is being investigated on 

 the Scates farm. Gallatin County Extension Adviser Earl Lutz and U. of I. Plant 

 Pathologist Ed Burns are working on the chemical control of P. maydis on the 

 Williams farm. 



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 Coo ley , Col- 

 lege of Agriculture , University of Illinois at Urban a- Champaign , and the Illinois 

 Natural History Survey. 



WEEDS: Marshall McGlamery , Department of Agronomy . 



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



AG COMMUNICATIONS: Ray Woodis . 



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

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

 Service, Plant Pest Control Branch. 



