长沙地区大白菜根肿病发生规律研究

长沙地区8月中.下旬播种的大白菜于9月上、中旬开始出现根肿病.10月中旬至11月初盛发.其侵染来源主要为土壤带菌、寄主作物除大白菜外,尚有小白菜、红菜苔、排菜、包菜、花菜、萝卜、等,大白菜以苗期易感此病.一般稻田改菜田、连作田以及播种早、土壤pH值低,秋季高温多雨等均可加重发病.

STUDIES ON THE OCCURRENCE OF CHINESE CABBAGE CLUBROOT IN CHANGSHA

Clubroot (Plasmodiophora brassicas Woron) appears on Chinese cabbage (Brassica pekinensis), which is usually sown in mid or late August, in Changsha district in early or mid September,and becomes severe in the period from mid October to early November. Its primary infection source is mainly infected soil, and its hosts include Chinese cabbage B.chinensis, B.chinensis var, tsaitai, B.juncea var. multiceps, B.oleracea var. capitata, B. oleracea var. botrytis and Raphanus sativus etc.. Chinese cabbage is most susceptible to clubroot at the seedling stage. When it is sown early and transplanted in rice fields or infected fields, dlubroot will be very severe. The disease is also favoured with low pH value of soil, high temperature and frequent rain in fall.