The Integrated Management Of An Emerging Insect Pest Of Cashew: A Case Study Of The Cashew Root And Stem Borer, Plocaederus ferrugineus In Ibadan, Nigeria

Abstract

Sudden death of mature cashew trees at the Cocoa Research Institute of Nigeria (CRIN), Ibadan, southwestern Nigeria, a tropical humid ecology, necessitated an urgent study to unravel the cause and evolve an integrated management strategy for the control of the problem. Morphometric examination of the adult insect recovered from dying cashew trees revealed that, Plocaederus ferrugineus (cashew root and stem borer) was the pest responsible for the sudden death and Spondias mombin (purple mombin) was identified as an alternative preferred host plant of this pest. Phytosanitation practices like removing infested-dead cashew trees and alternate host plant (Spondias mombin) was carried out. This phytosanitary practice was also recommended to other cashew growers in the region. Application of coal tar–kerosene mixture in ratio 1:2 to healthy trees within infested plots gave 100% prophylactic efficacy at twelve months after treatment. Chemical control using Propoxur (a carbamate) and physical control by poking of holes created by the borer using a wire and killing of the insect both gave 98% success rate each. With mode of damage to cashew and about 25% trees infestation per hectare recorded so far, the cashew root and stem borer, P. ferrugineus can now be classified as one of the most economically important insect pests of cashew in Nigeria.