Genetic Analysis of Dodine

HERE has been a small amount of published information on the genetics of the heterothallic ascomycete causing root and fruit rot of cucurbits. In these publications the fungus has been referred to as Hypomyces solani f. cucurbitae. However, according to DINGLEY (1961), this organism belong to the species Nectria haenzatococca and should be called N . haematococca var. cucurbitae. Genetic knowledge available includes inheritance of mating type, of male and female sterility, of perithecial and ascospore color, and of resistance to some aromatic hydrocarbon fungitoxicants (HANSEN and SNYDER 1946; EL-ANI 1954a; GEORGOPOULOS 1963b). In an earlier communication (KAPPAS and GEORGOPOULOS 1968) we reported on the genetic basis of resistance to n-dodecylguanidine acetate in the cucurbit pathogen. This compound, commonly known as dodine, cyprex, or melprex, has been in use for many years as a successful agricultural fungicide. Its mechanism of action has been studied mainly by BROWN and SISLER (1960), SOMERS and PRING (1966), and BARTZ and MITCHELL (1970a, 1970b). Recently, resistance to dodine has become a matter of much practical concern in New York State (SZKOLNIK and GILPATRICK 1969) where the fungicide is no longer effective against lapple scab (Venturia inaequalis) . Details on the genetic control of dodine resistance in N . haematococca var. cucurbitae will be presented in this paper.