Impact of companion cropping on incidence and severity of maize ear rots and mycotoxins in Western Kenya

Abstract

Mycotoxins are harmful to health and mainly arise from ear rots, affecting maize in the field. This work analysed the effect of the cropping system on ear rot and final effect on mycotoxins from four subcounties (districts) of western Kenya, Butere, Kisumu, Siaya and Vihiga, where plots comprising maize planted either as pure stand or in mixture with legumes, predominantly common bean treated as “Maize Monocrop” (MM), were used as control for those of climate-smart push-pull strategy treated as “Push-Pull” (PP). Symptomatic and asymptomatic maize ear samples were analysed for total aflatoxin (AF),total fumonisins (FB), deoxynivalenol (DON) and zearalenone (ZEA) using Enzyme-Linked Immunosorbent assay (ELISA). Cropping system had very high significant effect on ear rot incidence and severity. In general, low incidence was observed in PP (7.3 %) than MM (20.8 %). Similar trend was also observed on ear rot severity in PP and MM as follows: diplodia (1.15 and 1.85), gibberella (0.62 and 0.84), aspergillus (0.09 and 0.25), fusarium (0.19 and 0.68) and penicilium (0.03 and 0.05). A high proportion of ZEA (100%), AF (93.3%), DON (80.0%) and FB (65.9%) were observed in symptomatic samples than in ZEA (90.3%), DON (51.6%), FB (38.7%) and AF (3.2%) in asymptomatic samples. Low ear rot incidence and severity was more in PP than MM, and proportion of mycotoxins on asymptomatic ears; suggesting the potential of cropping system in managing ear rots and ultimately limiting mycotoxins. Thus the study highlighted the need to adopt cropping systems to deal with mycotoxins,and also recommends surveillance and awareness on emerging mycotoxins: ZEA and DON.