Resistência a fungicidas de Botrytis cinerea Persoon ex Fries, fungo causador de tombamento em mudas de Eucalyptus sp. em viveiros florestais

Abstract

The occurrence of fungicide resistant isolates of Botrytis cinerea Persoon ex Fries causal agent of Eucalypt seedling damping off, was evaluated in laboratory tests conducted at the Universidade Federal de Santa Maria (UFSM). To evaluate the fungicide effects on the mycelium growth and conidium germination, three active ingredients were tested: benomyl, procimidone and thiabendazole. The treatments consisted of four dosages for each fungicide: zero (control), one half of the recommended dosage, full dosage and twice the dosage. The evaluations were done every 24 hours during 7 days for the mycelium growth, and at 24 and 48 hours for spore germination. To determine the occurrence of resistance two isolates were compared, one from a commercial nursery in Rio Grande do Sul (IB-1), and the other (wild) (IB-2) from the Vegetable Crops Department, UFSM, Santa Maria, RS. The isolate IB-1 grew on all concentrations of benomyl, while the wild isolate was inhibited at all concentrations, indicating that the first isolate was resistant to benomyl.