Reaction of Potato Cultivars to Ralstonia solanacearum in Kenya

A survey of bacterial wilt (BW) incidence was carried out in three potato producing districts of Kenya, namely, Nyeri, Nyandarua, and Meru in 1997. The survey was carried out in 30 randomly selected farms in each district. Incidence of BW was highest (18.8%) in Nyeri district, intermediate (16.7%) in Meru and lowest (10.4%) in Nyandarua. A significant and negative correlation (P=0.05; r = -0.34) between bacterial wilt incidence and altitude was observed. Fifteen potato cultivars, Nyayo, Desiree CIP-800048, Roslin Tana, Kerrs pink LB-5, Golof (Dutch Robjin), B53, Tigoni CIP-381381.13, Rutuku CIP-720097, Asante CIP-381381.20, Kenya Dhamana CIP-800228, Mauritius Clone (89016), KP93739.26, KP92633.26, and Cruza148 CIP-72011 were subsequently evaluated for their reaction to Ralstonia solanacearum in artificial and natural infections in the greenhouse and in the field. Although none of the cultivars appeared resistant, there were significant (P=0.05) differences in bacterial wilt incidence and severity among the cultivars. Cultivars Kenya Dhamana, Mauritius and Cruza (CIP-720118) had low bacterial wilt severity and incidence and were rated tolerant, whereas the other cultivars were rated moderately susceptible or very susceptible. Une enquête sur l'incidence de la bactériose (BW) a été conduite en 1997 dans trois districts producteurs de la pomme de terre au Kenya; Nyeri Nyandarua et Meru. L'enquête a été conduite dans 30 fermes sélectionnées aléatoirement dans chaque district. L'incidence de BW était élevée (18.8%) dans le district de Nyeri, intermédiaire (16.7%) dans Meru et faible (10.4%) dans Nyandarua. Une corrélation négative significative (r=-0.34, P