Fusarium glume spot of wheat: A newly recorded mite-associated disease in South Africa

Fusarium poae was frequently isolated from necrotic lesions on wheat glumes in South Africa. Glume infections were usually associated with the mycophageous mite Siteroptes avenae. Microscopic examination of S. avenae feeding on F. poae cultures revealed the presence of two elongated sporothecae containing microconidia of the fungus. Spray inoculation of adult wheat plants with a suspension of F. poae microconidia produced water-soaked lesions on leaves and black chaff-like symptoms and necrotic awns. When the suspension was injected through the ,glumes into florets, or when F. poae-fed mites were transferred to the glumes of uninfected plants, symptoms typical of those observed in the field were reproduced. A close association appears to exist between S. avenae and F. poae and evidence suggests that both the mite and fungus are responsible for causing Fusarium glume spot of wheat in South Africa.