Infestation Outbreak of the African sugarcane stalk borer Eldana saccharina W. (Lepidoptera: Pyralidae) in Sugarcane Plantations of Northern Ivory Coast: Management Strategies Under Implementation

Heavy stalk borer infestations broke out over the last three cropping seasons in sugarcane plantations of both Ferké sugar mills of Northern Ivory Coast.The study objective was to determine the cause of heavy infestation observed on cane and sugar yields in order to implement a proper pest management strategy.The study which covers from 2006-06 to 2017-18 cropping seasons was based on sampling of all sugarcane plantations at harvest for cane juice analyses and assessment of stalk borer damages in terms of percentage of internodes bored.This allowed to cluster harvested lands depending on the intensity of infested canes and assess the amount of sugar production losses due to E.saccharina.It came out that infestations of this borer observed at harvest broke out only three years ago in Ferké 1 and two years ago in Ferké 2. Heavy infestations occurred over 45-55 % of the sugarcane area in Ferké 1 as opposed to 25-35 % in Ferké 2. Except for variety SP71-8210, all main sugarcane varieties grown were only heavily infested in Ferké 1.Although infestations were of concern on plantations no matter their water status, they seemed to be much more severe on rainfed and semi-irrigated crops compared to irrigated ones.Sugar production loss due to E.saccharina occurred over the last three years in Ferké 1 as opposed to the last two years in Ferké 2 but more importantly in 2016-17 for both sites with, respectively, a loss of 2600 and 2300 tons of sugar.Significant reduction in sugar production as a result of the limitation in nitrogen fertilizer rates was achieved in 2017-18 compared to 20116-17 by 62 and 50 %, respectively, in Ferké 1 and Ferké 2. This was one aspect of an integrated stalk borer management strategy to be implemented involving the www.videleaf.comapplication of silicone fertilizer, the growing of resistant or tolerant cane varieties and cropping practices preserving natural enemies such as mechanized green harvesting and growing service plants.