Waxy bloom on capsules is a major determinant of early infection by gray mold (Amphobotrys ricini (N.F. Buchw.) Hennebert) in castor (Ricinus communis L.)

Gray mold is a major disease of castor caused by the pathogen Amphobotrys ricini. It mainly affects the inflorescence resulting in severe yield losses. Role of qualitative characters of inflorescence (spike) and capsule viz. spike compactness, capsule type, waxy bloom intensity on capsules (visual), capsule spine length, spine texture and spine density in predisposing castor crop to gray mold was investigated. A set of 26 castor lines differing for presence and intensity of bloom was characterized for spike and capsule characters. The lines were screened in vitro (detached spike and capsule techniques) and in vivo by raising the plants in poly house and field conditions for disease reaction. Spearman's rank correlation analysis revealed significant positive correlation (rs = >0.5; p =