Evaluation of taro leaf blight disease (Phytophthora colocasiae) incidence on Kenyan and Pacific Island taro (Colocasiae esculenta) accessions in Kakamega (Western Kenya)

Abstract

Taro (Colocasiae esculenta) is an important staple crop for millions in most parts of the world. Humans obtain important nutrients such as calcium, phosphorus, iron, Vitamin C, thiamine, riboflavin and niacin from Taro. However its production in Kenya has faced challenges, such as the taro leaf blight disease caused by the fungus Phytophthora colocasiae. Racib that produces spores which are released in water and spread through rain splashes during the Kenyan rainy season when infection increases due to high temperature and high humidity. Pathogen control has relied on the use of fungicides that are too expensive. This study was thus initiated to evaluate the Phytophthora colocasiae disease incidences under field condition in Western Kenya. Disease incidence was assessed on two taro accessions namely; Colocasiae esculenta var antiquorum (L) Schott and Colocasiae esculenta var. esculenta (L) Schott when the total number of leaves and the number of infected leaves counted was expressed as a percentage of the total number of leaves per plants of each accession under varying climatic factors such as; Relative humidity, temperature and rainfall collected during the duration of the study period in Kakamega, Kenya. The data obtained when subjected to analysis of variance (ANOVA) showed higher percentage of mean disease incidence on Kenyan taro accessions than the Pacific island taro accession, thereby indicating a high adaptability of the Pacific taro to Kenyan weather conditions. After this study, it became clear that the high effect of weather parameters appeared to have an effect on disease incidences. Pathogen Infection increased under high relative humidity (86%), high temperature (29.6⁰C) and high rainfall amounts (223.9mm). These results support the urgent need to develop sufficient control measures for the Kenyan taro accessions, possibly through genetic manipulation of the from Pacific taro so as to come up with resistant accessions suitable for Kenyan weather that consists of a humid, warm and high annual rainfalls.