Occurrence of f u s a r i u m head blight, associated mycotoxins and resistance of wheat germplasm

Abstract

Fusarium head blight (FHB) is an important disease of wheat that reduces yield and quality through contamination with mycotoxins detrimental to human and livestock health. Major wheat varieties grown in Kenya are susceptible to FHB and there is no known source of resistance to the disease available. This study was carried out to determine the occurrence of F u s a r i u m head blight, associated mycotoxins and the level of susceptibility of wheat germplasm to FHB and deoxynivalenol (DON) contamination. A survey was carried out during the 2013 cropping season in four agro-ecological'zones (AEZ) in Nakuru County to determine wheat production practices and incidence and severity of FHB in each farm. F u s a r i u m species and mycotoxins DON and T2-toxin were determined in wheat heads and kernels. Nine wheat varieties and four CIMMYT lines were evaluated for susceptibility to FHB in field experiments at diverse agroecolgical zones in Nakuru and Narok Counties and in the greenhouse. After inoculation with F . g r a m i n e a r u m susceptibility was determined based on FHB severity, reduction in grain yield, kernel infectionand DON contamination in kernels. Majority (47.4%) of the farmers used certified wheat seeds and variety Njoro BW2 was the most widely grown. Most (63.4%) of the farmers used wheat straw to make hay for livestock feed, applied soil amendments (100%), practiced crop rotation (81.3%) while only 6.5% of the farmers practiced mixed cropping. Rust was the most important disease in all the farms surveyed. Head blight was prevalent (100%) in all the agro-ecological zones and mean incidence and severity ranged from 10.6 to 12.5% and 12.9 to 2 0 . 9 % , respectively with the highest incidence and severity in agro-ecological zone LH3. The most frequently isolated F u s a r i u m spp were F . g r a m i n e a r u m , F . avenaceum and F . p o a e . Most wheat samples were contaminated with mycotoxins DON and T-2 toxin upto 182ng/g and 37ng.g respectively.