Suitability of Van der Planks ‘r’ the rate of Increase of an Epidemic in Estimating the Rate of Whip elongation in Sugarcane Genotypes and Smut Isolates

Philip W. Marchelo-d’Ragga

Abstract

 

 

Accepted 23^rd March, 2015

 

Field studies were conducted at the Sugarcane Research Center at Guneid, (latitude 15⁰N, longitude 33⁰E), for two consecutive seasons 2008/09 and 2009/10. The objectives were to determine the rate of smut whip elongation, thickness, and length in some selected sugarcane genotypes. No significant differences were detected for whip thickness in the different smut isolates and sugarcane genotypes, however, significant differences (P=0.05) were found for whip length in the different sugarcane genotypes. The mean logarithmic rate ‘r’ of smut whip elongation was 0.07 cm day^-1 for all the tested varieties. However, in the individual varieties it is between 0.05 and 0.09 cm day^-1. The rate of smut whip elongation was found to be unrelated to the resistance/ and or susceptibility ratings of the individual sugarcane genotypes.

 

Keywords: Smut isolates, epidemic, elongation rate; sori; thickness; Ustilago scitaminea;

 

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