Leaf rust epidemics of certain promising cowpea varieties compared by using logistic and Gompertz models
1988
Chandrashekar, M. | Anilkumar, T.B. | Saifulla, M. (University of Agricultural Sciences, G.K.V.K. Campus, Bangalore (India). Dept. of Plant Pathology) | Salimath, P.M.
Rates of development of Uromyces phaseoli vignae on 9 determinate, semi-determinate and indeterminate varieties of cowpea grown in Hessargatta, India were monitored to compare the resistance of the varieties to rust. Weekly observation of rust severity recorded as uredia/sq cm was subjected to Gompertz or logistic transformations before computing apparent infection rates. Guj-2 and RC-19 showed highly resistant response to rust and V-105 supported few late injections. Comparison of the remaining varieties showed V-16, V-70, V-118 have very low infection rates. C-152, S-488, RC-48, V-118, V-16 and V-70 would take 25, 51, 57, 65, 83 and 99 days to record 50 % rust severity. Although both models effectively linearized diseased proportions, the Gompertz model generally produced lower standard errors of estimation, higher correlation coefficients and a more accurate estimation of apparent infection rates
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