OCCURRENCE OF RHIZOCTONIA SOLANI INDUCED STEM ROT ON COWPEA {VIGNA UNGUICULATA (L.) WALP} IN NORTH - WEST NIGERIA

Abstract

Cowpea stem rot was reported to cause significant yield loss whichvaries with the associated organism. Observance of typical symptomsof stem rot in some parts of North West Nigeria prompted this studywith the objective of assessing and identifying the causal organism ofthis disease. The incidence and severity of cowpea stem rot in farmers’fields were assessed during 2013 and 2014 rainy seasons. Four cowpeaproducing states of North - West Nigeria: Kano, Kaduna, Katsina andZamfara were selected and three Local Government Areas from eachwere surveyed. The results showed that the incidence and severityrecorded in these states significantly varied (p ≤ 0.05). Fields inKaduna State had significantly higher incidence (29.09 %) andseverity (21.14 %) than those in Kano, Katsina and Zamfara Statesfor the two seasons. Katsina State had the lowest incidence (9.24 %)and severity (7.31 %) of the disease. The fungi isolated from diseasedcowpea stem on Potato Dextrose Agar (PDA) were identified asRhizoctonia solani, Macrophomina phaseolina, Sclerotium sp.,Colletotrichum capsici, Fusarium solani and Curvularia lunata with R.solani recording the highest occurrence. Pathogenicity of the isolatedfungi on susceptible cowpea variety SAMPEA 10 was conducted andonly Rhizoctonia solani produced the typical stem rot symptomsobserved on farmers’ fields while the other isolated fungi inducedother symptoms. It is thus concluded that R. solani induced stem rotis wide spread in North - West Nigeria with varying incidence andseverity influenced by weather condition.