The Symptoms and Occurrence Regularity of Black Tip Disease of Ziziphus jujuba Mill.in Shanxi Province

Five jujube gardens in Jinzhong were investigated to determine symptom,spatial distribution pattern and occurrence regularity of black tip disease.The investigation showed that this disease generally occurred in jujube production areas(Sigua,Limeizhuang,Wangcun,Dongya,Nanliu,etc.).In these areas,the most serious area was at Sigua.Incidence and disease index of Huping jujube were 73.6% and 63.45% respectively.Symptom of the disease was darkening and shrinkage at the fruits stylar end,but not decomposed.Disease spots on jujube fruit was bitter and unedible.Moreover,these fruits lost the commodity value.The disease appeared in fruit expanding period,white ripe period and mature period.Small light-yellow spot was found firstly at fruits stylar end.Then the spot became bigger,dark brown and crimpled.Occurrence regularity of the disease is more serious on top and edge than that under and inside the tree.There is no center disease trees and the center units.It appeared uniformly distributed.The black tip disease happened seriously near the brick kilns,and was not serious or no happened far from the brick kilns.Occurrence regularity of the disease accords with the regularity of the noninfectious diseases.