Occurrence and pathogens of fruit shrink disease in Ziziphus jujuba Mill.

摘要

The occurrence of fruit shrink disease in Ziziphus jujuba Mill. ‘Linyilizao’ was investigated from 2006 to 2009 in Cangxian of Hebei Province, Taiyuan, and Taigu of Shanxi Province, and the pathogens were isolated from the diseased fruits sampled from both Cangxian and Taiyuan in 2006 and 2007. The pathogens in leaf, fruit, and shoot collected from Cangxian were isolated from June to October in 2008 at 30-day intervals. The incidence of the disease varied significantly with location and year, and the highest incidence was observed in Cangxian during 2006. Three kinds of key pathogens were isolated from the fruits from July to September, i.e., Alternaria alternata Keissler (mainly in July), Phoma destructiva Plowr. (mainly in September), and Fusicoccum sp., of which A. alternata was the most dominant. In leaves, both A. alternata (much more dominant) and P. destructiva could be isolated throughout June to October, but no Fusicoccum sp. was found. At the white-ripening stage of fruit, the isolation rate of A. alternata was the highest in leaves (36.67%), followed by extension shoot (6.67%) and fruit (1.11%) while that of P. destructiva was the highest in extension shoot (31.11%), followed by fruit (13.33%) and leaf (12.22%), with Fusicoccum sp. isolated only in extension shoot (2.22%). The frequency of isolating two or three kinds of above three pathogens together was very low, with the highest rate (19.30%) found in A. alternata and P. destructiva from leaves in July.