Occurrence of mycotoxin producing Fusarium species and other fungi on wheat kernels harvest in selected districts of Kenya

Abstract

Wheat samples collected from 5 wheat growing districts of Kenya were investigated for contamination by different fungi. Kernels were plated on agar media and the fungi that grew were identified by cultural and morphological characteristics to genus level. Fusarium isolates were identified to species level and isolates of F. graminearum were tested for mycotoxin production in culture. The major genera of fungi isolated according to decreasing frequency were Epicoccum (52.8%), Alternaria (34%), Fusarium (6%), Aspergillus (2.3%) and Penicillium (1.8%). The frequently isolated Epicoccum species was identified as E. purpurascenes. Cladosporium and Rhizopus spp. were also isolated at very low frequencies. The most frequently isolated Fusarium species were F. poae (43%), F. graminearum (39%), and F. avenaceum (8%). Other Fusarium species isolated were F. equiseti, F. oxysporum, F. camptoceras and F. chlamydosporium. Most isolates of F. graminearum produced mycotoxin deoxynivalenol and zearalenone. The isolated Fusarium species are known to cause head blight in wheat resulting in mycotoxin contamination of the grains. The results therefore indicated that head blight is widely distributed at low levels in the wheat growing areas investigated. This inoculum is potentially capable of producing severe infections under optimum weather conditions.