Incidence Of Fusarium Species And Levels Of Fumonisin B1 In Sorghum And Finger Millet In Western Kenya

ABSTRACT. 

This study was carried out to determine the incidences of Fusarium species, fumonisin B1 and aflatoxin B1 production in sorghum and finger millet grains collected from selected districts of Western Kenya region. The grains were collected randomly from five locations per district in Nyamira, Kakamega, Busia and Teso districts respectively. Ten farmers per location were randomly selected and samples of 0.25 kg of grains were picked per variety. A total of 16 sorghum varieties and 14 finger millet varieties were collected from the four districts. There were 19 morphologically distinct Fusarium species isolated from sorghum and finger millet grains. These included; Fusarium compactum, F. equiseti, F. thapsinum, F. verticillioides, F. longipes, F. andiyazi, F. nygamai, F. pseudonygamai, F. brevicatenulatum, F. chlamydosporum, F. heterosporum, F. napiforme, F. graminearum, F. pseudograminearum, F. oxysporum, F. solani, F. subglutinans, F. semitectum and F. proliferatum. Fusarium compactum and F. equiseti were the most isolated species in all the districts in both grains while F. thapsinum and F. verticillioides were isolated in sorghum varieties from all the districts. Sorghum had significantly higher percentage incidences of Fusarium species than finger millet. Nyamira district had the highest incidences at 65.47% and Kakamega had the lowest at 11.12%. Wagiita variety of sorghum had the highest incidences at 58.95% while Esila had 0% isolation of Fusarium species. All finger millet varieties had low incidences of Fusarium of less than 8%. The levels of fumonisin B1 detected in sorghum grains (48.81 μg/g) were significantly higher than those in finger millet grains (1.13 μg/g). Sorghum from Nyamira district had the highest fumonisin B1 levels at 76.63 μg/g while low levels of 17.59 μg/g were detected in Busia. Ochuti and Wagiita varieties of sorghum had the highest fumonisin B1 levels, while no fumonisin B1 was detected in KARI Mtama-1 and Esila. Ikhumba variety had levels within the detection limits of 1.75 μg/g. Some finger millet varieties had the lowest levels of fumonisin B1 which were at the detection limit levels of 1.75 μg/g each while some had no fumonisin B1 detected. The aflatoxin B1 in sorghum from Busia and Teso districts had levels below the detection limit of 2 ppb. From the results, finger millet grains are safe for consumption especially when weaning children but sorghum might cause mycotoxicoses. Results also shows that farmers should be sensitized on the dangers of fumonisin B1 levels in sorghum and be advised to adopt varieties like KARI Mtama-1, Esila (with no fumonisin B1 detected) and Ikhumba that had very low levels of fumonisin B1. Some of the fumonisin levels found in this study coincide with levels associated with risks to humans and animals reported in other countries.