Effects of Some Benzoxazinoids on in Vitro Growth of Cephalosporium gramineum and Other Fungi Pathogenic to Cereals and on Cephalosporium Stripe of Winter Wheat

摘要

The benzoxazolinones benzoxazolin-2(3H)-one (BOA) and 6-methoxybenzoxazolin-2(3H)-one (MBOA) and selected degradation products of these compounds were examined for their in vitro antifungal activity against Cephalosporium gramineum,Gaeumannomyces graminis var.graminis,and Fusarium culmorum.BOA was also applied to the soil-incorporated inoculum of C.gramineum to test its capability of reducing Cephalosporium stripe disease in winter wheat.MBOA reduced the mycelial growth of G.graminis var.tritici,C.gramineum,and F.culmorum by 50% (EC_(50)) at the concentrations of 77,134,and 271 mu g/mL of corn meal agar,respectively,and the corresponding BOA EC_(50) values for the fungi were 11,189,and 456 mu g/mL.BOA degradation products 2-amino-3H-phenoxazin-3-one (APO),2-acetylamino-3H-phenoxazin-3-one (AAPO),and o-aminophenol (o-AP) were much more inhibitory to the growth of C.gramineum and G.graminis var.tritici than the parent compounds.APO,AAPO,and o-AP EC_(50) values were found to be as low as 0.58,4.57,and 1.4 mu g/mL,respectively,for C.gramineum and 0.78,2.18,and 0.80 mu g/mL for G.graminis var.tritici.These compounds applied at the corresponding concentrations did not significantly affect the mycelial growth of F.culmorum.The treatment of C.gramineum inoculum with a 1 % water solution of BOA resulted in a significant reduction infection of winter wheat with C.gramineum as compared to the control with the untreated inoculum,but this treatment was not as effective as the application of a commercial fungicide.