| dc.description.abstract | Survey on fungal and aflatoxin contamination and evaluation of possible management
strategies was carried after 2006/07 cropping season in nine agro ecological zones of
greater Machakos district (Kangundo, Machakos and Yatta districts). The overall
objective of the study was to assess fungal and aflatoxin contamination in maize in the
greater Machakos district and evaluate possible management strategies to mitigate the
aflatoxin problem.
Questionnaires were used to gather information on production, storage, handling, and
consumption practices. Samples of whole maize, semi-processed grains, posho mill
sweepings, soils from farms and from under the maize stores were collected. Fungi from
whole maize and semi-processed grains were isolated by direct plating, while for posho
mill sweepings and soil by pour method and the fungi identified to species level.
Aflatoxin contamination was determined using ELISA method. Field experiments were
conducted to evaluate susceptibility of selected varieties to fungal and anatoxin
accumulation. The varieties were inoculated with Aspergillus flavus isolated during the
survey. Aspergillus rot was evaluated by visual ear rot rating scale.
Most (88.0%) farmers planted their own selected local maize, some did not practice
rotation, most (54.0%) harvested maize without husk, dried maize in cob form (94.4%)
and on mats or polythene (56.7%). Most farmers stored shelled maize in houses in
polypropylene bags (93.3%). Most traders sourced maize from local farmers (97.6 %)
and commonly transported the maize by oxen pulled carts (49.8 %).
The major fungal genera isolated [rom the samples were Fusarium, Aspergillus and
Penicillium. The most frequently isolated Aspergillus species were A. flavus. and A.
niger. Aspergillus jlavus and anatoxin levels in maize grains from farmers were found to
be significantly different across agro-ecological zones. Semi-processed grains had the
aflatoxin level of 5.1 ug/kg while posho mill sweeping had a level of 18.3 ug/kg.
There was significant di fference among the maize varieties 111 Aspergillus rot rating
during the long rains. Aspergillus flavus was re-isolated from cobs inoculated with A.
flavus during long rains (19.0%) and short rains (9.9%). There was no significant
difference among the varieties in Aspergillus rot rating and re-isolation of Aspergillus
jlavus during short rains. Aspergillus jlavus was re-isolated from the inoculated maize
samples. Varieties were not significantly different in anatoxin content.
The results showed that anatoxin contamination of maize and maize products could be as
a result of interaction of production, harvesting, storage, handling practices and presence
of A. jlavus in soil, residues from previous crop and grain left over under store. All the
varieties tested were susceptible to aflatoxin contamination. Training farmers on good
agricultural practices, further work on susceptibility of a broad range of maize varieties
grown in Kenya under diverse environments would be required. Continuous anatoxin
surveillance in anatoxin hotspot areas is necessary. In addition, more research on
Fusarium mycotoxins in maize would be necessary. | en |
