Plasmopara helianthi Novot. is the causal agent of downy mildew of sunflower (Helianthus annuus L.). In Italy the first sporadic attacks were reported from Umbria in 1970 and, since 1973, the disease became economically important with infection rates of up to 90% recorded during 1970-78. P.helianthi has not represented a serious problem since the 1980's due to the introduction of resistant varieties and the use of systemic fungicides as seed dressing. Recently, in sunflower crops a low percentage of sistemically infected plants and some other ones with an unusual symptomatology (light stunting, no chlorosis nor sporulation on leaves) were observed. Although hyphae and haustoria of P.helianthi were observed in tissues of atypical downy mildew plants it is difficult to give an explanation for this symptomatology because it was not possible to reproduce these symptoms in artificial inoculations.

Downy mildew of sunflower: a new unusual aspect of symptomatology

TOSI, Laura;ZAZZERINI, Antonio;
1997

Abstract

Plasmopara helianthi Novot. is the causal agent of downy mildew of sunflower (Helianthus annuus L.). In Italy the first sporadic attacks were reported from Umbria in 1970 and, since 1973, the disease became economically important with infection rates of up to 90% recorded during 1970-78. P.helianthi has not represented a serious problem since the 1980's due to the introduction of resistant varieties and the use of systemic fungicides as seed dressing. Recently, in sunflower crops a low percentage of sistemically infected plants and some other ones with an unusual symptomatology (light stunting, no chlorosis nor sporulation on leaves) were observed. Although hyphae and haustoria of P.helianthi were observed in tissues of atypical downy mildew plants it is difficult to give an explanation for this symptomatology because it was not possible to reproduce these symptoms in artificial inoculations.
1997
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/925443
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