Plant quarantine significance of dwarf bunt of wheat to China

Abstract

The adaptability of Tilletia controversa was studied in particular relation to China, where wheat is cultivated under various climatic conditions. Teliospore germination is closely influenced by temperature, light and soil humidity. Establishment of T. controversa depends on: (1) persistent low temperature (0–10°C) within the surface layer of the soil, in combination with adequate soil moisture; (2) presence of seedlings of susceptible wheat cultivars, especially in the early stage of tillering before or during overwintering. The climatic conditions of various wheat‐growing areas in China were compared with the results obtained in this study, and areas of prevalent damage and of marginal damage were predicted. It was concluded that T. controversa presents a considerable hazard to China if it accidentally enters.

Use of geographic information systems and satellite data for assessing climatic risk of establishment of plant pathogens

“…Johnsson (1992) suggested that both low temperatures during autumn and persistent snow cover during winter were associated with high incidence of dwarf bunt. Cloud cover may contribute to infection of dwarf bunt during winter (Zhang et al 1995).…”

“…where N C [0, 1] represents monthly frequency of clouds with visible optical depths > 6 and where f is a correction factor. Zhang et al (1995) reported that in China about 5% of wheat was infected by dwarf bunt under cloud cover conditions, whereas Hoffmann (1982) reported that about 60% of susceptible cultivars were infected under persistent snow cover. In the present study, the value of f was assumed to be 0.08 at first.…”