Efficiency of Wood Vinegar Extracts from Eucalyptus and Neem Trees for Controlling <I>Colletotrichum gloeosporioides</I>

Abstract

Assays on the efficiency of wood vinegar extracts of eucalyptus and neem trees in controlling Colletotrichum gloeosporioides were carried out. The methods used in this study included isolation of the C. gloeosporioides from mango cv. ‘Nam Dok Mai’, sensitivity assays of the C. gloeosporioides to the carbendazim fungicide and inhibition activity assays of wood vinegar extracts of eucalyptus and neem trees to the C. gloeosporioides. The results showed that from a total of 131 C. gloeosporioides isolates that isolated from mango cv. ‘Nam Dok Mai’, 94 isolates (71.76%) were highly resistant (HR), 2 isolate (1.53%) was moderately resistant (MR) and 35 isolates (26.72%) were sensitive (S) to the carbendazim fungicide. Three isolates, one from each phenotype, were selected in the inhibition activity assays of the wood vinegar extracts of eucalyptus and neem trees to the C. gloeosporioides. Both wood vinegar extracts were screened for their inhibition activity against C. gloeosporioides on agar plates by mixing the extracts with potato dextrose agar (PDA). In this experiment, both wood vinegar extracts could completely inhibit the hyphal growth of C. gloeosporioides (100% efficiency) at 2% (v/v) concentration, and showed inhibition activity to the conidial germination of C. gloeosporioides (100% efficiency) after 24 hour at 1% (v/v) concentration. The lower eucalyptus vinegar extract concentration could inhibit the hyphal growth and conidial germination better than neem vinegar extract. The inhibition activity assays was also carried out by soaking mango fruits into eucalyptus vinegar extract at 1, 2 and 3% (v/v) concentration for 1, 3 and 5 min. The soaking mango fruits in 1% eucalyptus vinegar extract for 1 min produced the highest inhibition activity on the anthracnose disease incident of the mango fruits. The vinegar extract smell wad faded away within a day. Using this combination, the mango fruits did not show any anthracnose symptom up to 16 days incubation period while the control had shown the symptom over the mango. The skin and taste were not differences from the mango before soaking. In conclusion, wood vinegar extract of eucalyptus wood has a potential as an alternative agent for controlling anthracnose disease of mango fruits.