Ozone effects on fungal leaf diseases of wheat in relation to epidemiology. 1. Necrotrophic pathogens
1992
Tiedemann, A. v. (Goettingen Univ. (Germany). Inst. fuer Pflanzenpathologie und Pflanzenschutz)
Wheat plants at growth stages tillering, stem elongation, ear emergence and anthesis were exposed to 80, 160, 240 mig m(-3) ozone for 5 days (7 h per day) and to charcoal-filtered air. Post-exposure inoculation with Septoria nodorum or Bipolaris sorokiniana revealed a faster growth of lesions on ozonated leaves. However, whereas maximum size of Septoria lesions was measured on leaves exposed to the highest concentration of O3, Bipolaris lesions developed best at 160 mig m(-3) and were significantly reduced at 240 mig m(-3) O3. These predisposing effects were largely independent of the four growth stages tested. The latent period of S. nodorum was inversely related to the lesion growth and particularly shortened by ozone at growth stages (GS) 37 and 55. The latent period of B. sorokiniana was most strongly shortened at GS 65 (anthesis). It is concluded that both diseases may be enhanced by ozone throughout the main growing season of wheat and that in particular S. nodorum epidemics may be accelerated by shortened latent periods at decisive stages of the early season
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