OCCURRENCE AND CONTROL OF YELLOW SPOT OF WHEAT IN NORTHEASTERN AUSTRALIA

Explanations were sought for the increased severity of yellow spot of wheat (Pyrenophora tritici-repentis) in the north-eastern wheat growing areas of Australia. A close association between the severity of yellow spot and stubble management practices was found in a field experiment. There was less disease in plots where stubble had been burned (0.83 lesions per leaf) or burned and cultivated (0.62) than in plots which were mechanically cultivated (2.43) or untreated (11.75). In another study severe yellow spot developed as early as in the second wheat crop in a rotation. Differences in susceptibility to the disease were found among 11 wheat cultivars and lines. Vigorous development of the pathogen occurred on cereal rye and triticale while the fungus was isolated from small lesions on barley and four common grasses. Avoidance of planting wheat into infected wheat stubble, either by crop rotation or removal of surface stubble by incorporation or burning, should provide effective control of the disease in most situations. © 1979 ASEG.