Effects of Temperature and Relative Humidity on Expression of Resistance toCercosporidium personatumin Peanut

Publisher Website
Google Scholar
Abstract
Detached peanut [Arachis hypogaea] leaves were inoculated with the leaf spot pathogen Cerosporidum personatum and exposed to 20, 24, 28, or 32 C for 6 days. Maximum infection occurred at 20 C, provided leaves also were exposed to at least 12 hr/day high relative humidity (RH > 93%). Infection of genotypes with high (PI 259747, NC Ac 17133), moderate (GP-NC 343), and low (NC 3033, Robut 33-1) partial resistance decreased with increasing temperature. Few infections occured at 28 and 32 C regardless of duration of the high relative humidity period. Daily periods of high relative humidity shorter than 12 hr also reduced the number of infections on all genotypes regardless of temperature. Ranking of genotypes by lesion numbers was similar at all temperature and relative humidity periods tested. Lesions on leaves of PI 259747, NC Ac 17133, GP-NC 343, NC 3033, and Robut 33-1 were largest, developed most rapidly, and sporulated most profusely at 24 C. Lesions on FESR 5-P2-B1, a genotype reported to have high combining ability for leaf spot resistance, developed fastest at 28 C. Postinfection development of C. personatum was completely inhibited at 28 C on the highly resitant genotypes, and at 32 C on all genotypes.