Occurrence of Fusarium Species in Symptom-free and Overwintered Cornstalks in Northwestern Minnesota. Carol E. Windels, Assistant Professor, Northwest Experiment Station, University of Minnesota, Crookston 56716. Thor Kommedahl, Ward C. Stienstra, and Patricia M. Burnes. Professor, Professor, and Assistant Scientist, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Dis. 72:990-993. Accepted for publication 1 July 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0990.

Incidence of stalk rot in 50 cornfields sampled in early October 1985 and 1986 averaged 1 and 2%, respectively. However, six Fusarium species were isolated from cornstalks without stalk rot symptoms. F. subglutinans predominated and colonized 30% of stalks in 1985 and 86% in 1986; F. graminearum colonized 20 and 37% for the 2 yr; F. proliferatum, 5 and 13%; F. avenaceum, 3% both years; F. culmorum, 1 and 3%; and F. moniliforme, 1 and 2%. F. graminearum was isolated from 26% of corn debris collected from 14 fields in 2 yr, F. avenaceum from 12%, and F. culmorum from 4%. Incidence of stalk rot (or infected stalks) in fields containing carryover stalk debris was the same as that in fields where debris was absent. Isolates of F. graminearum were in group 2 in that perithecia were produced by 99–100% of the isolates from cornstalks and 1-yr-old stalk debris.

Keyword(s): Gibberella zeae, Zea mays.