In vitro fungicide sensitivity of root rot disease causal agent <i>Phialocephala bamuru</i> isolated in New Jersey from hard fescue

Abstract Fungal pathogen Phialochephala bamuru that causes fairway patch on warm‐season turfgrasses in Australia is recently observed to cause severe root rot disease in New Jersey on cool‐season turfgrass hard fescue ( Festuca brevipila ). Symptoms begin as small tan colored patches but can develop into irregular ring‐like blighted turf upward of 3 m in diameter. Little is known on the control of this disease, with a few reports on the ineffectiveness of single and multiple active ingredient products in the field. To better identify the effective fungicides in controlling P. bamuru , 39 fungicides were evaluated in vitro for suppressing the growth of P. bamuru . Fungicides were added to a 10% potato dextrose agar media, and a P. bamuru mycelium plug was placed in the center of each plate for hyphal radial growth to be measured. Variable growth of P. bamuru was observed, indicating different fungicide sensitivities. Twelve fungicides belonging to five chemical families completely inhibited P. bamuru growth. Ten of these fungicides were then evaluated for the disease control efficacy in the field. This study showed effective P. bamuru inhibition by selective synthetic fungicides in vitro, but field efficacy remained unclear and requires further research.