Demonstration and Evaluation of Potato Varieties and Fungicide Spray Frequencies for Management of Late Blight (Phytophthora infestans) Disease in Silte and Hadya Zone, Southern Ethiopia

Metiku Kebede

Abstract

Late blight disease caused by Phytophthora infestans is one of the major constraints on potato production in Ethiopia. The present research was designed with the aim of evaluating potato varieties and fungicide application frequencies for the management of late blight. The combinations of two different potato varieties with three different levels of fungicide application frequencies were used in Alicho wuriro and Analomo research substation during 2014 and 2015 main growing seasons. The experiment was laid out in randomized complete block design in factorial arrangement with three replications. Unsprayed controls were also included to allow maximum disease severity for comparison. The interaction effect of potato varieties and fungicide application frequency significantly (p≤0.05) affected disease severities, Area under disease progress curve (AUDPC) and tuber yield. The result of the study revealed that the maximum disease severity of 19.5 to 55.9% at Alicho wuriro and 23 to 49.8% in Analimo was recorded in plots sprayed three times and plots without spraying, respectively. There was a significant negative correlation between disease incidence, severity and AUDPC to that of yield with correlation coefficient ranging from r=–0.47** to r=–0.95**. The trials clearly determined the appropriate fungicide frequency for management of the late blight. The improved Jallene variety combined with three applications of Ridomil MZ 63.5% WP gives the highest commercial yields. However, more research is needed to determine the appropriate frequency of fungicides in different agro-ecologies, with integration of host resistance, for more inclusive recommendations.

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