Screening Peanuts for Resistance to Sclerotinia Blight

Abstract

Sclerotinia blight, caused by Sclerotinia minor, results in peanut (Arachis hypogaea) crop losses of 4–6% annually in Virginia. Sclerotinia minor attacks plant parts that are in contact with the soil, causing lesions on stems and branches as well as pod rot. Three field screening tests were conduced in 1977, 1978, and 1979 to identify resistant peanut genotypes. The genotypes Chico, PI 371521, and VA 71-347 exhibited a significantly lower incidence of Sclerotinia blight symptoms in 1977 field screening than Starr, NC 17, Florigiant, and two breeding lines. Chico, NC 3033, VA 71-347, and VGP 1 exhibited significantly fewer Sclerotinia blight symptoms in 1978 field screening than GK 3, Early Bunch, NC 6, Florigiant, and six breeding lines. Under severe disease pressure, VA 71-347 had the highest value per hectare, being significantly higher than GK 3, Early Bunch, and Florigiant. In 1979, Chico, NC 3033, VA 71-347, and VGP 1 exhibited significantly fewer Sclerotinia blight symptoms than 20 other entries, including Florigiant, Tifrun, NC 7, and Early Bunch. VA 71-347 had a significantly higher yield and value per hectare than all other entries in 1979. The influence of plant canopy structure, morphological and physiological aspects of resistance, use of multiline peanut cultivars to reduce genetic vulnerability, and multiple pest resistance as related to Sclerotinia blight are discussed