Survey of fusarium species infecting winter wheat in England, Wales and Scotland, 1989 and 1990

Abstract

* In 1988 the International Commission on the Taxonomy of Fungi renamed Fusarium nivale, Microdochium (perfect stage = Monographella nivalis).

Fusarium* species infecting winter wheat were surveyed in fields from the Agricultural Development and Advisory Service (ADAS) Regions and Scotland at growth stages (GS) 31 and 73 in 1989 and 1990 and in grain samples taken from the same fields at harvest. Assessments of stem-base diseases at GS 31 were based on definitions and photographs of 9 symptoms of disease in 1989 and 10 in 1990. F. nivale was the most prevalent of the Fusarium species isolated from the stem base at both GS 31 and 73. F. culmorum and F. avenaceum were also apparent on the stem base, the former increasing in incidence at GS 31 in 1990. These two species increased in prevalence at the later growth stage. F. poae was the most prevalent species on the ears. In vitro sensitivity tests using a range of fungicides on isolates obtained at GS 31 showed high levels of sensitivity to prochloraz and varying levels of sensitivity of F. nivale to benomyl.

F. culmorum was the predominant species in grain samples from England and Wales in 1989 and as prevalent as F. poae in 1990. F. nivale was also relatively common in grain samples particularly in Scotland. However, overall levels of both fusarium and blackpoint (Alternaria alternata) in grain were generally low. One grain sample from Scotland contained a fusarium toxin and a second contained a toxin derived from Alternaria. Trichothecenes were detected in 25% of the wheat grain samples from England and Wales and zearalenone in one. Of the Fusarium species tested isolates of F. poae produced the most toxic of the mycotoxins.

The possible influence of environmental factors on the incidence and severity of Fusarium species, the level of mycotoxin production, and the implications of control measures on stem base disease interactions and crop establishment are discussed.