Using of some Fungicides to Control Green Rot Disease on Corn (Zea mays) Caused by Aspergillus flavus and Their Effect to Reduce Its Product of Aflatoxin.

Abstract

This study is aimed to combat the fungus Aspergillus flavus and reduce its resulting aflatoxin B1 by chemical control using of four fungicides , namely : Carbendazim, Chlorothalonil , Mancozeb and Tebuconazole . Effect of these four fungicides on fungus radial growth is tested using food poisoned technique at three concentrations for each 10ppm, 100ppm, 1000ppm for a week of incubation at 27 C˚ and showed that all fungicides have had a disincentive effect on fungus growth at all of its tested concentrations but in varying proportions. Tebuconazole at all of its tested concentrations was ahead of other used fungicides. Significant differences were found between control and all of other treatments; 10 ppm of Carbendazim, Chlorothalomil ‚ Mancozeb, Tebuconazole had realized following inhibition percentages 92.2% ,81.1% 53.3% ,93.0% respectively and increased consequently with further increase of fungicides concentrations from 100 ppm 94.4,83.3 ,93.3 ,94.4 to 1000 ppm 96.6%, 88.8% ,95.5% ,97.0% respectively. Filed trial using same four fungicides indicated that Tebuconazole was the best with following values of disease percent and disease index 23%,5% followed by Mancozeb 23%,5% and Carbendazim 26%,5% and Chlorothalonil came in the last order 33%,5% respectively. Significant differences were found between these treatments from a side and fungus inoculated and non-inoculated control treatments from other side 54%, 14%, 29 and 6% respectively. Investigation for aflatoxin B1 using of ELISA detection technique resulted that all samples taken directly from the field were contaminated with aflatoxin in varying concentrations compared with fungus inoculated and non-inoculated control treatments which showed 11.722+ˉ0.409 ppb and 11.951+ˉ0.620 ppb respectively. while samples taken from field treated with four fungicides; Carbendazim , Chlorothalonil ‚Mancozeb, and Tebuconazole gave following aflatoxin concentrations 42.345+ˉ9.842 ppb , 22.202+ˉ1.016 ppb , 29.073+ˉ7.317 ppb , 27.280+ˉ0.480 ppb respectively.Investigation for aflatoxin B1 in same treatments but in samples taken after five week of storage showed that aflatoxin concentration among four fungicide treatments; samples taken from Tebuconazole treatment were less in its aflatoxin concentration 11.899+ˉ0.824 ppb followed by Chlorothalonil 12.499 +ˉ 1.015 ppb and Mancozeb 14.341± 2.00 ppb and finally Carbendazim 17.337±1.124 ppb.