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Disease Detection and Losses

Relationship Between Yield Loss and Severity of Early and Late Leafspot Diseases of Peanut. P. A. Backman, Department of Botany, Plant Pathology, and Microbiology, Alabama Agricultural Experiment Station, Auburn University 36849; M. A. Crawford, Department of Botany, Plant Pathology, and Microbiology, Alabama Agricultural Experiment Station, Auburn University 36849. Phytopathology 74:1101-1103. Accepted for publication 11 May 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1101.

Levels of peanut leafspot caused by either Cercospora arachidicola or Cercosporidium personatum were adjusted by applying fungicides of differing effectiveness. Disease levels 2- 3 wk before harvest were related to dry pod yield. In studies conducted for 4 yr, data indicated that for cultivar Florunner peanuts with a yield potential of about 4,400 kg/ha, yield was reduced by an average of 57 kg/ha for each percent of defoliation. Peanuts could tolerate low levels of infection, but all levels of defoliation resulted in yield loss. No difference in loss-producing potential (yield loss per unit of disease) was observed between C. arachidicola and C. personatum, since similar levels of disease caused similar losses. However, slopes of regression lines did differ significantly when years were compared.