INDUCTION OF RESISTANCE AGAINST VERTICILLIUM DAHLIAE IN CACAO BY A CRINIPELLIS PERNICIOSA SUSPENSION
F.R. Cavalcanti, M.L.V. Resende, P.M. Ribeiro Junior, R.B. Pereira, J.T.A. Oliveira
This study deals with the potential of reducing Verticillium wilt in susceptible cacao using a fungal suspension compared to a commercial resistance inducer. Plants were sprayed with acibenzolar-S-methyl (ASM; Bion® 50 WG (0.2 g l-1) and a heterogeneous chitosan suspension (MCp) from Crinipellis perniciosa mycelium. Plants were challenged five days later with a virulent isolate of Verticillium dahliae, under greenhouse conditions. A reduction of Verticillium wilt severity was observed in plants treated by the substances tested, with MCp reaching 80% of ASM protection performance. To evaluate local and systemic activation of defences, cacao leaves and hypocotyls exposed to ASM and MCp were assayed for peroxidase, polyphenol oxidase and lignin deposition. Local induction of resistance was confirmed by the increase of chitinase and β-1,3-glucanase activities in the leaves, 4-18 days after spraying. Treated and inoculated plants showed, in the leaves and hypocotyls, increased lignin deposition, which is associated with the cacao defence strategy against Verticillium wilt.