Preliminary report on the experiment of screening chemical defoliant for Sanhua plum
Forcing early leaf dropping in Sanhua plum can achieve secondary flowering and promote off-season early maturing culture.Defoliation experiment during the growth season of 5-year-old Sanhua plum fruit trees was conducted by spraying agentia such as abscisic acid,ethephon,thidiazuron,and lime sulphur.The results showed that spraying 10 to 15 times liquid of 45%lime sulphur on the entire plant had the best overall effect.Thirty days after treatment of lime sulphur,the defoliation rate was more than 80%,wtih the old leaves com-pletely defoliated,leaving only young leaves at the top of tree.The process of defoliation was slow,which was conducive to the accumulation of nutrients in the tree,and could also play a role in clearing orchard.The defo-liation rate of ethephon treatment was 100%after 15 days of spraying,but it was easy to cause phytotoxicity and had a great impact on the growth of Sanhua plum tree.Therefore,ethephon was not recommended for subsequent use as Sanhua plum defoliator.