Analysis of Changes in Area of Cylindrocladium Black Rot in Peanut Fields Utilizing False-Color Infrared Photography. B. W. Perry, Former Graduate Research Assistant (deceased), Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg 24061. G. J. Griffin, and N. L. Powell. Professor, Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg 24061, and Associate Professor of Agronomy, Tidewater Agricultural Experiment Station, Suffolk, VA 23437. Plant Dis. 73:42-45. Accepted for publication 21 July 1988. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0042.

Changes in Cylindrocladium black rot (CBR) area in 31 Virginia peanut fields were assessed over a 6-yr period (1974–1979) with aerial, false-color infrared photography. A general increase in CBR area per field and total number of CBR foci was found for the period, except in 1978. For fields planted in peanuts during 1974, 1976, and 1978, the disease was found to be greatest in 1976, when the mean area of CBR per field was 2,935 m². A decrease in CBR area per field in 1978 (1,835 m²) was believed to result from low temperatures during the winters of 1976–1977 and 1977–1978. For fields planted in peanuts in 1975, 1977, and 1979, the largest areas of CBR per field were found in 1977 (2,734 m²) and 1979 (2,660 m²), even though one or two severe winters intervened. Less CBR area per field in 1975 (2,187 m²) than in later years may have been due in part to a summer drought, which slowed CBR symptom development. Individual fields sometimes showed distinct patterns on CBR area change. Decreases in CBR area in a few fields between 1974 and 1976 or 1977 and 1979 suggest these fields should be investigated as potential disease-suppressive soils. Patterns of new CBR focus development and enlargement in fields were consistent with proposed means of microsclerotial dispersal.

Keyword(s): Cylindrocladium crotalariae, groundnut.