Fusarium SPECIES ISOLATED FROM WHEAT SAMPLES CONTAINING TOMBSTONE (SCAB) KERNELS FROM ONTARIO, MANITOBA, AND SASKATCHEWAN

Abstract

The Fusarium spp. associated with samples of wheat seed containing tombstone kernels were identified for 454 samples collected in 1986 and 1987, representing six wheat classes from three provinces. The results indicate that the frequencies and distribution of the 13 species isolated were influenced by geographic location, growing conditions and wheat class. In 1986 and 1987, F. graminearum infected the most seeds and samples of Ontario-grown wheats. It was also the most frequently recovered species from Manitoba wheats in 1986, but was absent from the Saskatchewan wheats. In 1987, F. avenaceum was isolated from the greatest percentage of seeds from Manitoba and Saskatchewan. The greatest percentage of Manitoba samples in 1986 and 1987 were infected by F. sporotrichioides whereas F. acuminatum infected the most Saskatchewan samples. Only F. graminearum infected more than 7% of the seeds of any sample of Canada Western Red Spring, Canada Prairie Spring, Canada Eastern White Winter, Canada Eastern Red Winter, or Canada Eastern Red Spring class of wheat (to a maximum of 52%), whereas five species (F. acuminatum, F. avenaceum, F. equiseti, F. poae, and F. sporotrichioides) exceeded that level in one or more samples of the Canada Western Amber Durum class. The other seven Fusarium spp. (F. compactum, F. crookwellense, F. culmorum, F. proliferatum, F. oxysporum, F. pallidoroseum, and F. subglutinans) combined accounted for <5% of isolates. Overall, the lowest frequency of Fusarium spp. was found in the Canada Western Red Spring class of wheats, and the highest in the Canada Western Amber Durum class.Key words: Fusarium, wheat, disease, graminearum, avenaceum, scab