Maize ear rot and associated mycotoxins in western Kenya

Maize was established as the most important crop and cob rot as the most important crop protection problem in Western Kenya. The mean percentage rotten maize grain resulting from cob rot was 19% based on the PRA survey in Kapsabet and Tongaren Divisions and on-farm evaluation of the Kenyan hybrids in Tongaren Division in 1998 and 1999 seasons. The two important factors affecting the incidence of cob rot were the weather conditions at the period of maturation to harvest and stalk borer. Cob rot incidence was found to be strongly correlated with percentage borer damage (r = 0.87). Fusarium moniliforme was the most frequently isolated fungus in cobs that had stalk borer damage, occurring in 97% of the cobs that had rot and visible borer damage. F. moniliforme was found in 80%, F. graminearum in 56% and S. maydis in 49% of maize samples collected on the farms and markets in Western Kenya. Deoxynivalenol, zearalenone, fumonisin and aflatoxin were detected in samples collected from the farm and markets in the region. T-2 toxin was absent in all samples collected from the region. The levels of deoxynivalenol and zearalenone detected in the samples ranged from 0-1100 ng/g and 0-550 ng/g respectively and were mainly detected from rotten maize. The presence of zearalenone and deoxynivalenol is reported for the first time in maize in Western Kenya. Fumonisin and aflatoxin levels ranged from 0-2348 ng/g and 0-10 ng/g respectively. All the rotten maize harvested in the region was utilized as livestock feed and for brewing. Awareness of the potential risks associated with mycotoxins was low among the farmers and the extension workers. The Kenyan hybrids H627 and H622 were susceptible to Fusarium graminearum. The varieties did not show any difference in reaction to F. moniliforme and S. maydis. This fact was thought to be due to high disease pressure in the field and the genetic background of the hybrids