Occurrence of banana xanthomonas wilt in Kenya and potential approaches to rehabilitation of infected orchards

Abstract

Symptoms of banana Xanthomonas wilt (BXW) are confused with Fusarium wilt caused by Fusarium oxysporum f. sp. cubense. Therefore field diagnostic tools for BXW that are easy to use, fast, precise and effective are important in detecting the disease at early stages. The objective of the study was to evaluate the effectiveness of DNA capture field kits in polymerase chain reaction (PCR) diagnosis of BXW. Two-hundred and fifty eight samples suspected to be BXW were collected from East and Cetral African countries using the Twominute DNA capture field kit and Flinders Technology Associates (FTA) Whatman card field kits. Another set of of 36 fresh samples from the field in Kifu Uganda were collected and these were analysed by two-minute DNA capture field kit, FTA card field kits, ELISA and direct extraction of DNA for comparison. The captured DNA was subjected to PCR analysis for presence of Xanthomonas campestris p.v. musacearum (Xcm). Two-minute dipstick DNA capture field kit was found to be most efficient in capturing Xcm DNA under field conditions and it gave comparable results with Enzyme –Linked Immunosorbent Assay (ELISA) and direct extraction of DNA from fresh samples. Out of 258 field samples, 25.9% were positively diagnosed using two-minute dipstick DNA capture field kit and only 1.5% with FTA cards while out of 36 fresh samples 38.8% were positive with two-minute dipstick DNA capture field kit, 25% FTA cards, 38.8% direct for DNA extraction and 38.8% with ELISA methods. Two-minute dipstick DNA capture field kit was efficient in capture of Xcm DNA from both symptomatic and asymptomatic but infected banana plants. The two-minute dipstick DNA capture field kit enables sampling in remote areas without the need for complicated equipment.