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.

It is imperative to establish the distribution and density of soil fungal communities as a requisite for formulating strategies for management of ear rot infections and mycotoxin contamination. In a two seasons study, short (SR) and long rainy (LR) seasons, we investigated the distribution of Aspergillus and Fusarium fungi causing ear rots and producing mycotoxins from 120 soil samples collected from maize fields under push-pull (PP) and maize monocrop (MM) systems in Western Kenya. Cultural methods were used for identification of Aspergillus and Fusarium species, while molecular techniques were used for confirmation of Fusarium section Liseola. Detection of total aflatoxins in cultures of section Flavi isolates was carried out by enzyme-linked immunosorbent assay (ELISA). A total of 338 fungi were isolated; 80% were identified as Aspergillus and 4.4% Fusarium. The distribution of fungi was significant with season but not cropping systems. The frequency of occurrence was higher during the LR (68.4%) than the SR (31.6%). In cropping systems, the frequency of occurrence of Aspergillus flavus was higher in MM (60.2%) than PP (39.8%). However, Aspergillus parasiticus was more frequent in PP (71.4%) than MM (28.6%); and during the SR (78.6%) than the LR (21.4%). Majority (81.3%) of A. flavus and A. parasiticus were toxigenic. There was low recovery of Fusarium species in soil samples. These findings show that soils from both cropping systems are potential for Aspergillus infection and aflatoxins contamination; however, low Fusarium distribution in soil suggest external inoculum source for Fusarium ear rot infections common in most maize fields in Western Kenya.