Incidence and Distribution of Charcoal Rot of Sunflower Caused by Macrophomina phaseolina in Spain. R. M. Jiménez-Díaz, Professor, Departamento de Patología Vegetal, Escuela Técnica Superior de Ingenieros Agronomos, Universidad de Córdoba, Córdoba, Spain. M. A. Blanco-López, Adjunct Professor, Departamento de Patología Vegetal, Escuela Técnica Superior de Ingenieros Agronomos, Universidad de Córdoba, Córdoba, Spain; and W. E. Sackston, Professor, Department of Plant Science, Macdonald Campus of McGill University, Ste. Anne de Bellevue, Quebec H9X 1C0, Canada. Plant Dis. 67:1033-1036. Accepted for publication 11 May 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1033.

Charcoal rot of sunflower caused by Macrophomina phaseolina occurred throughout the main areas of sunflower cultivation of Spain in 1976, 1977, and 1978. Disease incidence varied widely among regions and years of sampling; it was most prevalent where low rainfall and high temperature coincided with flowering time. Highest incidence was observed in 1976; the disease was present in 76 of 163 fields and 25% or more of the plants were affected in 25 fields. Symptoms were most conspicuous from late flowering to early ripening. They included a dark brown to black discoloration at the stem base, small and distorted heads with a zone of aborted flowers, and premature ripening.