Abstract
Cylindrocladium crotalariae, which causes Cylindrocladium black rot (CBR) of peanut (Arachis hypogaea), can be isolated at a low frequency from nondamaged peanut seed (seed size ≥6.4 × 25.4 mm slotted screen) not treated with a seed protectant fungicide. Peanut seed obtained from peanut fields in Suffolk, VA, and Martin County, NC, where CBR was severe in 1985 were infected at a frequency of 1.5% and 1.4%, respectively. Cylindrocladium crotalariae was isolated at twice the frequency from pieces of seed than from whole seed. However, C. crotalariae was not isolated from seed treated for 2 weeks with a seed protectant (DCNA + captan). The fungus was not isolated from seed devoid of testae or seed embryos, but was isolated from seed testae at a frequency of 0.4%. Discolored seed (≥6.4 × 25.4 mm) were infected at a frequency of 7.9%, but following seed treatment, the isolation frequency dropped to zero. Discolored seed measuring < 6.4 × 25.4 mm were infected with C. crotalariae at a frequency often exceeding 10%.
Author notes
1Cooperative investigation by Agricultural Research Service, U.S. Department of Agriculture, Suffolk, VA 23437, and Virginia Polytechnic Institute and State University, Blacksburg, VA 240461.
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