Compatibility of three entomogenous nematodes (Rhabditida) in aqueous solutions of pesticides used in turfgrass maintenance

Aqueous solutions of nine pesticides used in turfgrass maintenance were tested for compatibility with entomogenous nematodes. A range of sensitivity among pesticide-nematode combinations was observed. The fungicides chlorothalonil, benomyl, and pentachloronitrobenzene (PCNB) and the herbicide dicamba were nontoxic to Neoaplectana carpocapsae Weiser (=Steinernema feltiae) (Rhabditida: Steinernematidae), N. bibionis Bovien, and Heterorhabditis sp. "HP-88" (Rhabditida: Heterorhabditidae). The carbamate insecticides carbaryl and bendiocarb were highly toxic to Heterorhabditis sp. "HP-88" but were less toxic to N. carpocapsae. N. bibionis was more highly sensitive to chlorpyrifos than were the other nematode species. Diazinon was significantly toxic only to Heterorhabditis sp. "HP-88" (48 h exposure). The inorganic mercurial fungicide Calo-Clor was highly toxic to all species tested; Heterorhabditis sp. "HP-88" were particularly sensitive. Generally, entomogenous nematode applications appear to be compatible with most of the turfgrass pesticides tested, although previous applications of persistent inorganic fungicides may preclude the use of the nematodes