杀菌剂对腐烂病菌在苹果树枝干上腐生定殖的防除效果OA

To screen effective fungicides for controlling apple Valsa canker and to establish a scientific method for fungicide evaluation,this study employed in vitro inoculation of apple branch cortex and a wound-induction method by knocking to damage the bark in order to induce lesions.The efficacy of different fungicides in protecting pruning wounds,blocking saprophytic colonization of Valsa mali,and eradicating pathogens that had already colonized the xylem of pruning wounds and surface tissues of branches was evaluated.The results showed that four fungicides,pyraclostrobin,thiophanate-methyl,tebuconazole,and Bordeaux mixture,exhibited good protective effects on pruning wounds and effectively prevented saprophytic colonization of V.mali in the xylem.The protection efficacy of these fungicides was all above 80％,with a persistence period exceeding 20 days.Thiophanate-methyl demonstrated a certain eradication effect on pathogens that had colonized the xylem,but the eradication rate was lower than 60％.Pyraclostrobin and thiophanate-methyl exhibited strong eradication ability against newly colonized pathogens on the branch surface,with corrected eradication rates above 90％.However,among the six fungicides tested,none showed a significant eradication effect on overwintering pathogens in dead tissues on the branch surface or in wound tissues.In summary,the application of fungicides before or at the early stage of saprophytic colonization can effectively block pathogen colonization.Once the pathogen colonizes deeper tissues,however,the eradication efficacy of fungicides becomes very limited.These findings provide effective fungicide options and screening methods for the management of apple Valsa canker.