Harnessing the Potential of Selected Bio-agents for Sustainable Management of Plant Parasitic Nematodes in Coffee

Abstract

East Africa confronts multiple challenges in coffee production, including aging plantations, subpar inputs, climate change, and pest-related issues. Among these threats, plant parasitic nematodes (PPN) pose a significant concern, contributing to estimated global losses of up to 15% in coffee production. Despite their impact, PPN often remain overlooked or underestimated as a major factor causing damage to coffee crops. In Kenya, specific symptoms of PPN damage are poorly understood, leading to their gradual manifestation over years and resulting in enduring losses to the industry. Biocontrol has been explored in management of PPN on other crops like horticultural, ornamental and other annual crops but has not been registered in coffee, a perennial crop. This study aimed to assess the potential of microbial antagonists in suppressing PPN and improving coffee production in Kenya. The effectiveness of three biocontrol agents namely Trichoderma asperellum, Purpureocillium lilacinum, and Bacillus subtiliswas evaluated under pot and field conditions, targeting Meloidogyne hapla, a prevalent nematode species affecting coffee in the Ruiru region of Kenya. In pot experiment, nematode-infested soil and roots from Chania Coffee Farm was utilized. Three Biocontrol agents, namely Bacillus subtilis, Trichoderma asperellum and Purpureocilium lilacinum were tested. Each of biocontrol agent was administered at three different rates: 6.67 × 103, 6.67 × 104, and 6.67 × 105 spores/ml, using a randomized complete block design with 20 treatments and five replicates. Drenching with 150 ml of the biocontrol agent occurred every two weeks for six months after transplanting, with assessments conducted at the experiment's termination. Two biocontrol agents, Trichoderma asperellum and Purpureocilium lilacinum, were tested in the field experiment. The recommended dose for other annual crops, 2 × 107 spores/ml, was applied in seven fields, each with three treatments and four replicates, spanning for two years. Drenching each plant with 40 ml of the respective product in 20 liters of water was done monthly after subsequent soil sampling. Monthly activities included soil sampling, nematode extraction, quantification, and identification, as well as fungal re-isolation...