Progress and outlook for the control of nivalenol and deoxynivalenol contamination due to Fusarium head blight in wheat.

Abstract

Use of appropriate fungicides is most effective and reliable practice to control Fusarium head blight (FHB). Therefore, re-evaluation of registered fungicides and screening new candidates for control of mycotoxin contamination are considered mandatory. We found that seven chemicals; metoconazole, tebuconazole, captan, thiofanate-methyl, oxine-copper, copper-hydroxide and phosphorous acid would control deoxynivalenol (DON) and nivalenol (NIV). On the contrary, treatment of azoxystrobin significantly increased the level of DON and NIV compared to the control plots, even though it reduced disease severity of FHB. We propose that new fungicide evaluation system based on efficacy for mycotoxin contamination should be introduced. In order to develop effective strategies for controlling the risk of toxin contamination, we investigated the manner in which toxin accumulation occurs in grain. The results indicated (i) high levels of DON and NIV can be produced beyond 20 days after anthesis (DAA) even by early infection, and (ii) infection at a late stage, at least as late as 20 DAA, can cause grain contamination with these toxins. Thus, developing control strategies that cover the late stage as well as the early stage would be desirable to reduce the risk of toxin contamination in wheat.