Biocontrole in vitro de Ceratocystis fimbriata (Ellis & Halsted) por isolados de bactérias antagonistas

Abstract

Ceratocystis wilt caused by the pathogen Ceratocystis fimbriata is one of the main diseases of some forest species. It is a vascular disease and chemical control is not used, as there is no registration of fungicides in the Ministry of Agriculture and Supply for this disease. The present work aims to evaluate the antagonistic capacity of soil bacteria isolates on the mycelial development of Ceratocystis fimbriata in vitro. The antagonism test was based on the double culture methodology. The growth of microorganisms inoculated in culture medium in Petri dishes occurred in the incubator at a temperature of 28 ºC ±1 ºC for 10 days. The evaluations were carried out by daily measurements of the diameter of the phytopathogen colonies, being estimated the following variables: average mycelial growth (CMM), mycelial growth velocity index (IVCM), percentage of inhibition of growth (PIC) and colony area (cm²). In the antagonism test, the UFVD16 isolate showed a lower average mycelial growth and lower mycelial growth velocity index on the 4th day after inoculation, as well as UFVD05 and UFVD16 isolates on the 10th day. As for the percentage of inhibition, it was found that on the 4th day the highest percentage of mycelial inhibition was from the UFVD16 isolate, with 64.85%, statistically differing from the other treatments. The UFVD16 isolate showed a promising effect in vitro on the mycelial growth of the pathogen Ceratocystis fimbriata, being a potential alternative to be evaluated in field tests for the management of this pathogen. More studies and in vivo tests are needed to assess its potential for application in the field.