Ceratocystis fimbriata Ellis & Halsted em espécies florestais no Rio Grande do Sul: comportamento e controle biológico

Abstract

Pathogens of the genus Ceratocystis are polyphagous, attacking several species of economic importance, such as black wattle, eucalyptus, mango and cocoa, these have wide variability even within a single genus or species, the result of adaptations to the environment they live in and the hosts available. Study the behavior of these pathogens such as Ceratocystis fimbriata in forest species is important to understand the ways of survival variability and fungus resistance mainly native species. The use of biocontrol as of the genera Trichoderma and Bacillus, have been widely studied as an alternative for the biological control of soil borne pathogens. Hence, the present work aims to study the behavior of different isolates of C. fimbriata obtained from kiwi (Actinidia deliciosa) in forest species as black wattle (Acacia mearnsii), guava (Psidium cattleianum), araucaria (Araucaria angustifolia), cherry (Eugenia involucrata) and inga (Inga marginata); potential biocontrol in vitro Trichoderma spp. and Bacillus subtilis about C. fimbriata and the in vivo behavior of B. subtilis in seedlings of black wattle , against C. fimbriata as an alternative control . For this purpose, we used isolates of C. fimbriata obtained and identified in kiwi plantations. In the pathogenicity test isolates were evaluated for their pathogenic variability and behavior on seedlings of black wattle, guava, araucaria, cherry and inga. Through direct confrontation testing was analyzed in vitro antagonistic potential of Trichoderma spp. and B. subtilis on the pathogen. For the evaluation of the in vivo behavior of B. subtilis black wattle seedlings were inoculated with product Rizolyptus®, seven days before and seven days after pathogen inoculation. Seedlings inoculated with native species C. fimbriata showed no sign of wilting or discoloration of the tissues. However, in seedlings of Acacia mearnsii isolates of C. fimbriata exhibited severity percentage ranging from 44.15 to 100%. In direct confrontation testing isolates of Trichoderma spp. and B. subtilis demonstrated to be effective in vitro on biocontrol isolates of C. fimbriata with percentages of inhibition ranging from 46.48 to 57.76 and from 14.12 to 32.20 % respectively. In biocontrol in vivo test, the Rizolyptus® product was not effective in controlling C. fimbriata and all black wattle seedlings inoculated with the pathogen showed symptoms of wilting and death.