you must rely on resistant varieties for control. More details are given in Re- 

 port on Plant Diseases No. 106, "Bacterial Blights of Oats," available from the 

 Department of Plant Pathology, 218 Mumford Hall, Urbana, Illinois 61801. 



SOYBEAN SEEDLING DISEASES 



Recent rains and the cool, cloudy weather have kept many fields on the wet side. 

 As a result, we have received many soybean specimens at the Plant Disease Clinic 

 that show signs of Rhizoctonia, Pythium, and Phytophthora root rots. 



Rhizoctonia infection produces sunken, reddish-brown lesions on the main root 

 and stem below the soil line. Circular patches of dead plants, 4 to 10 feet in 

 diameter, may appear anytime from now until mid- July. 



Pythium- infected plants have soft, dark rotted areas that may extend up the stem. 

 These areas become translucent and water-soaked. They often tear away when the 

 plant is pulled from the soil. Infected plants usually appear singly or in small 

 groups, and will probably cause little yield reduction. 



Phytophthora root rot is characterized by dark-brown lesions on the root and stem. 

 These lesions extend as much as 6 inches above the soil line, as opposed to the 

 reddish-brown decay caused by Rhizoctonia. Yellow plants killed by Phytophthora 

 occur in sections or rows in the low areas of a field. 



Planting healthy, high-quality seed in warm, well-drained soil is the only con- 

 trol measure available for Rhizoctonia and Pythium. All varieties are uniformly 

 susceptible. There are many varieties highly resistant or immune to Phytophthora 

 rot. These should be planted in poorly drained soils where there is a history 

 of Phytophthora. Report on Plant Diseases No. 504, "Root and Stem Diseases of 

 Soybeans," contains more details. It is also available from the Department of 

 Plant Pathology. 



READ THE LABEL AND FOLLOW ALL PRECAUTIONS 



This weekly report was prepared as follows: 



INSECTS: H.B. Petty, Steve Moore, Roscoe Rand e 11 , Don Kuhlman, and Tim Cooley , 

 College of Agriculture , University of Illinois at Urbana-Champaign , and the Illi- 

 nois Natural History Survey. 



WEEDS: Ellery Knake and Marshal McG lamer y , 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. 



