Euphytica 29 (1980) 175-176 INHERITANCE OF RESISTANCE TO ANGULAR LEAF SPOT (ISARIOPSIS GRISEOLA SACC.) IN FRENCH BEAN (PHASEOLUS VULGARIS L.) A. K. SINGH and S. S. SAINI Department of Vegetable Crops & Floriculture, Himachal Pradesh Agricultural University, Solan (H.P.) India Received 21 May 1979 INDEX WORDS Phaseolus vulgaris, French bean, Phaseolus coccineus, runner bean, Isariopsis griseola, angular leaf spot, resistance. SUMMARY Angular leaf spot (Isariqsisgriseola SACC.)is a serious disease of French bean in the hills of India and 40 to 70 per cent of the green pods are damaged and rendered unmarketable. Crosses were made between PLB 257, (Phaseolus coccineus L.), a red flowering pole type, resistant to angular leaf spot, and Contender (Phaseolus vulgaris L.), a highly susceptible commercial cultivar. Studies of the F,, F,, and F, progenies indicated that PLB 257, carries a recessive gene imparting resistance to angular leaf spot. 1NTRODUCTlON Angular leaf spot (Z.sariopsisgriseola) is a serious disease of French bean, an important crop grown in the hills in India during the summer months. The infected green pods are disfigured and thus rendered unmarketable. Crop losses due to this disease are often considerable. The French bean (P. vulgaris) cultivars grown in India are susceptible to this disease. Cultivar PLB 257, (P. coccineus), was observed by us to be resistant to angular leaf spot. This study reports on the mode of inheritance of PLB 257’s resistance and the attempts to transfer this resistance to the commercial cultivar Contender, and hence into other French bean varieties. MATERIALS AND METHODS PLB 257 (P. coccineus), a red flowering pole type was used as the resistant source and Contender (P. vulgaris), a commercial cultivar as the susceptible parent. Parents, F,, F,, and F, were raised and planted in the monsoon season so that the plant growth period coincided with high humidity and temperature favouring the incidence of this disease. To ensure uniform incidence of the disease under field conditions; i) parasite-contaminated plots were selected, ii) artificial epiphytotic con- ditions were yearly created by spraying fresh spore suspensions, prepared by mixing freshly infected leaves with srerilised water, on the experimental plants, iii) the highly susceptible cultivar Premier, (P. vulguvis), was planted all around the experiment and in between the treatment rows. 175