Field Evaluation of Potential New Fungicides for Control of Downy Mildew of Broccoli in 1994 and 1995

Abstract

Downy mildew of broccoli is caused by the plant pathogenic fungus Peronospora parasitica. Cool damp weather with high humidity is highly favorable for sporulation, dissemination of spores, and infection by this pathogen. The severity of disease is affected by the duration of weather conditions favorable for disease development. Potential new fungicides were evaluated for disease control in field trials conducted during 1994 and 1995. Downy mildew did not occur in the 1994 trial. In 1995, disease was moderate and all tested fungicides provided significant disease control compared to no treatment at all. Three new fungicides, Fluazinam, Dimethomorph, and ICIA-5504, show promise as potential new materials for control of downy mildew on broccoli.