Characterization of the relationship between leaf spot severity and yield in new peanut runner-type cultivars and effects of new peanut genotypes on leaf spot epidemics
Navia Gine, Pablo Alejandro
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New peanut (Arachis hypogaea) cultivars ‘Florida-07’, ‘Georgia-06G’, ‘Georgia-07W’, and ‘Tifguard’ were combined with four different fungicide treatments in multiple field trials in 2010 and 2011 to examine the relationship between percent defoliation, caused by Cercospora arachidicola or Cercosporidium personatum, and pod yield. Decline in yield was no more than 14.4 kg per % increase in defoliation in all cultivars and trials, which was lower than previously reported. Canopy reflectance was correlated with percent defoliation in most cases. Field trials were conducted in Tifton, GA and Marianna, FL to evaluate field reactions of new peanut genotypes developed as part of the USAID Peanut CRSP program. Four genotypes (97x45-HO1-2-B2G-1-2-1-2, 98x64-2-2-1-2b4-B, 96x72-HO1-10-2-1-b4-B, and CRSP 1048-192T) showed moderate levels of field resistance to C. personatum. Incidence of stem lesions caused by C. personatum was higher for Florida-07 than for Georgia-07W or Tifguard.