Preliminary Study On The Effect Of Walnut Shell Pyroligneous Acids Against Apple Replant Disease

Malus domestica is one of the prop industries of fruit industry in Hebei province.At present,apple replant disease has become an important limiting factor for apple yield,quality and orchard renewal.In this study,the inhibitory effect of pyroligneous acids from walnut shell on Fusarium equiseti and Fusarium oxysporum,the the pathogens of apple replant disease in Hebei province was determined by laboratory experiments to determine the optimal inhibitory concentration and treatment method.The main rootstock of Malus robusta Rehd.was used as the test material in Hebei province.The soil of different concentrations of pyroligneous acids from walnut shell were used to verify.The best field test concentration and treatment method were selected.The results showed that:(1)Pyroligneous acids from walnut shell can significantly inhibit the spore germination of two Fusarium sp.spores.The pyroligneous acids diluted 100 times and 200 times can significantly inhibit the spore germination,and the inhibition rate of Fusarium spore?s germination reached 100% within 48 h,but after diluted 400 times,the inhibited effect of pyroligneous acids was declined.Pyroligneous acids can significantly inhibit the growth of mycelium after 72 hours of hyphae growth.The inhibition rate of pyroligneous acids with different times diluted on F.equiseti were 15.49%,11.70% and 9.81%,respectively,the inhibition rate on F.oxysporum were 13.94%(100 times)and 10.76%(200 times),and there was no significant inhibition of 400 times dilution of pyroligneous acids.(2)The results in field test showed that 100 times diluted pyroligneous acids significantly promoted the plant growth leaf area,soil organic matter and main mineral elements,and increased soil related enzyme activities.(3)Mix 100 times pyroligneous acids from walnut shell with slag,and field experiments were compared with other commercially available replanting agents.Each treatment had no significant effect on the number,structure and diversity of bacteria.100 times pyroligneous acids + slag treated soil can significantly reduce the proportion of Fusarium sp.in fungal community,significantly increase soil organic matter and N,P,K content,increase soil urease and soil sucrase activity,promote seedling shoot growth and increase the leaf area.