Host range of Alternaria alternata f.sp sphenocleae causing leaf blight ofSphenoclea zeylanica

Forty-eight plant species in 40 genera representing 20 families were screen ed for susceptibility to Alternaria alternata (Fr.) Keissler f.sp. sphenocl eae, a candidate biological control agent for Sphenoclea zeylanica Gaertner (gooseweed). Gooseweed was the only species susceptible to A. alternata f. sp. sphenocleae when plants were treated with 3.5 x 10(5) conidia/mL (appro ximately 10(7) conidia/m(2)) in the presence or absence of supplemental dew . All inoculated gooseweed plants were killed when subjected to a 14- to 15 -h dew. Lactuca sativa L. (lettuce), Glycine max (L.) Merrill (soybean), Ph aesolus vulgaris L. (common bean), Psophocarpus tetragonolobus (L.) DC. (wi nged bean), Vigna radiate (L.) R. Wilcz. (mung bean), Vigna unguiculata (L. ) Walp. (string bean), Musa sapientum L. (banana), and some Oryza sativa L. (rice) cultivars showed highly resistant reactions. Brassica oleracea L. ( cabbage), Raphanus sativus L. (radish), and Abelmoschus esculentus (L.) Moe nch (okra) showed highly resistant to moderately resistant reactions while Gossypium hirsutum L. (cotton) showed moderately resistant to moderately su sceptible reactions. Symptoms on cotton were restricted to the cotyledons. Sporulation, however, was observed only on detached excised gooseweed leave s, and no sporulation occurred on any of the other plant species evaluated. Gooseweed was the only compatible host plant of A. alternata f.sp. sphenoc leae found in these studies.