Suspension Agaricus brasiliensis in the induction of phytoalexins and in the control of the grapevine downy mildew

The objective of this study was to verify the elicitor effect on phytoalexin induction and control of grapevine mildew (Plasmopara viticola) under field conditions of the micelial aqueous suspension (MAS) of Agaricus brasilienis. For the induction of phytoalexin in beans, soybean, sorghum and severity of mildew, treatments containing washed and unwashed A. brasilensis MAS, as well as with and without association with vegetable oil (VO), were used as control treatment with water and standards with acibenzolar-S-methyl (ASM 0,005%) and bordeaux syrup (1: 1: 1). In another experiment, also for the determination of phytoalexin induction in soybean and sorghum, the doses of 0, 1, 5, 10, 15 and 20% of MAS of A. brasiliensis were used. The 10% A. brasiliensis MAS was found to induce 1000% and 56% phytoalexin in beans and sorghum, respectively. For soybean, a 400% increase was observed with 5% of the washed MAS of A. brasiliensis. The doses of this suspension can be emphasized induction of 460% and 710% when using 20% of the MAS of the mushroom. In field conditions no statistical differences were reported between the treatments applied on the vines. Thus, it can be said that the MAS of A. brasiliensis presents compounds capable of eliciting elicitor behavior for resistance induction responses in plants, but no direct effect was observed on the pathogen evaluated.