关键词: 冬枣, 日灼病, 发病率, 调查

Abstract: The incidence of sunburn in the concentrated production areas of winter jujube in Hebei province in 2018 was investigated three times by field survey on July 23, August 7 and August 17, respectively. The results showed that the incidence of sunburn of winter jujube was correlated with the duration of high temperature and extreme temperature value positively. It also related to the location of fruits, showing a law that the incidence rate varies from large to small in the order of west, south, east and north, upper part had higher rate than lower one, in the meantime, external had a higher incidence than internal, with the lower and northern parts not appearing this disease. It related to the individual growth stage of the fruit because the larger fruit was more vulnerable to sunscald in the same position. Self-healing was a phenomenon among the winter jujube in a less serious disease of one level, healing itself or reducing injuries when the later meteorological conditions were more appreciate. In addition, the incidence was related to microclimate environment （underlying surface state） and management measures （for instance irrigation）.

Key words: winter jujube, sunburn disaster, morbidity, investigation