Efficacy of non-conventional fungicides for the suppression of dollar spot disease caused by Clarireedia jacksonii

Abstract

The potential for non-conventional fungicides to suppress dollar spot disease, caused by Clarireedia jacksonii, was investigated. Treatments were selected from reports in the literature, as well as from the Ontario Government Class 11 lowrisk pesticide list. Treatments found to be efficacious in both preliminary lab and field trials, including ferrous sulfate heptahydrate (FSH) (21% Fe), paraaminobenzoic acid (PABA) (100%) and Affirm WDG (11.3% polyoxin-D zinc salt), were compared across 10 cultivars of Agrostis stolonifera. Significant differences in cultivar response were observed with 1x FSH (250 g/100 m2) applications. On average, 1x FSH and 5x FSH suppressed dollar spot disease by 74 to 78% and 95 to 99% respectively. However, a significant darkening was observed with increasing rates of FSH, which led to phytotoxicity and scarring, especially during hotter periods.