Assessment of Fungicide Performance on Control of Downy Mildew of Broccoli in 1998

Peronospora parasitica is the pathogen responsible for causing downy mildew of broccoli, cabbage and cauliflower. Cool moist environmental conditions favor the development of downy mildew on these crops. Several potential new fungicides were evaluated for control of this disease on broccoli in 1998. The final severity of downy mildew in this trial was moderately high. Significant reduction in disease severity compared to nontreated plants was achieved by application of standard compounds such as Aliette, Bravo, maneb and Trilogy as well as the new fungicides Actigard, an Unknown, Curzate, Quadris, RH-7281, BAS 490, Acrobat and BAS 500. Broccoli yield was significantly increased compared to nontreated plots by treatments with Bravo, Curzate, Acrobat, BAS 500, Quadris, maneb, Actigard, BAS 490, an Unknown, RH-7281 and Aliette. The future registration and subsequent availability of one or more of these new chemistries for broccoli and related crops could help minimize the risk of development of resistance to fungicides used to manage downy mildew.