BIOCONTROL ABILITY OF Trichoderma harzianum ON GROWTH, DISEASE INCIDENCE AND YIELD OF SELECTED COWPEA VARIETIES (Vigna unguiculata L.) INFESTED WITH Colletotrichum lindemuthianum

Abstract

Cowpea anthracnose caused by Colletotrichum lindemuthianum causes about 75 % yield
reduction in Cowpea production in Nigeria. Trichoderma harzianum is a bioagent in controlling
fungal diseases. Effect of T. harzianum was investigated on growth, disease incidence and yield
of selected varieties of Cowpea infested with C. lindemuthianum. Four improved Cowpea
varieties were selected IT07K-292-10, IT07K-318-33, IT98K-205-08, IT99K-573-11 and a local
variety DANMISRA. Pure isolate of Colletotrichum lindemuthianum and Trichoderma
harzianum were each cultured on PDA. Four concentrations of T. harzianum suspensions were
prepared at 1x102 conidia/ml, 1x104 conidia/ml, 1x106 conidia/ml, 1x108 conidia/ml and control .
Cowpea seedlings were artificially infested with 1x107conidia/ml of C. lindemuthianum at 22
days after sowing. The experiment was arranged in a complete randomized design (CRD) with
three replications. The result indicated that the infested variety IT99K-573-11 treated with T.
harzianum at 1x108 conidia/ml was insusceptible and had significantly (p<0.05) increased
biomass, number of seeds and low disease incidence (19.1 %) while increase in chlorophyll
content, seed number and decreased in the anthracnose incidence was observed at 1x108
conidia/ml concentration. The cultivar IT99K-573-11 appeared tolerant hence is recommended
to farmer for cultivation in C. lindemuthianum infested areas.