Reaction of peanut cultivars to late leafspot and rust

Late leafspot caused by Phaeoisariopsis personata (Berk. & M.A. Curtis van Arx) and rust caused by Puccinia arachidis Speg. are among the most serious diseases of peanut. Although fungicide application is effective in controlling the diseases, its high cost is considered uneconomical in many developing countries. In this situation, the use of resistant cultivars offers a better alternative. The objective of this study was to evaluate seven peanut cultivars for their resistances to late leafspot and rust. Peanut cultivars were planted in a randomized complete block design (RCBD) with 4 replications at Khon Kaen University Experimental Farm. Natural infection of late leafspot and rust were allowed. Disease score, sporulation index and lesion number per 100 cm2 of leaf area were recorded as the resistance parameters of both diseases. Pod yield, seed yield, shelling percentage, pod number per plant and pod length were also measured. NC 17135 was the most resistant to late leafspot and moderately resistant to rust. NC 17090 was the most resistant to rust but susceptible to late leafspot. NC 17135 and NC 17090 should be recommended as sources of late leafspot and rust resistance, respectively. The two Thai released cultivars, Tainan 9 and Lampang were highly susceptible to both diseases