Study on the biocontrol efficiency and underlying antagonistic mechanism of valsa canker by pyrolysis tar from apple wood

Apple valsa canker, caused by V. mali, often leads to tree bark rot and yields decreasing. Wood tar, a by-product of biomass pyrolysis contains rich antimicrobial active substances. It has good bonding and waterproofing properties, which is ideal for the control of apple canker. In this study, wood tar obtained from pyrolysis of waste fruit wood was used as supplied test fungicides to explore the biocontrol efficiency and underlying antagonistic mechanism of wood tar against V. mali. Based on the bacteriostatic test, the field experiment was carried out to study the comprehensive control effects of smearing once or twice different times dilution wood tar a year after disease spots treated in different ways. The results showed that the concentrations of wood tar were positively correlated with the inhibition rate of hypha and residual duration, in which the inhibition rate of both 2 and 5 times dilution reached 100% and the residual duration lasted for 7 days. And the control effect of twice annual application after striking off diseased tree spots in zones I and II, after crisscrossing scratches on diseased tree spots in zone II gradually reduced with the increase of wood tar dilution times. The control effect of applying wood tar stock solution and 2 times dilution solution after three kinds of disease spot treatments were 100%, which were improved by 274.5%, 49.9% and 66.7% respectively compared with the control fungicides. The present study demonstrated that wood tar showed promising prospects for use as a biological control agent against apple valsa canker under field conditions.

Automated summary

Wood tar obtained from pyrolysis of waste fruit wood was used as a biofungicide to control apple canker caused by V. mali. The study showed that wood tar concentrations were positively correlated with hypha inhibition rate and residual duration. Wood tar demonstrated promising prospects as a biological control agent against apple canker.