一、棉田杂草种类和大致出土时间据初步调查,江苏滨海棉区的棉田杂草,计有10多个科,近30种,其中发生期长,发生量大,为害最严重的恶性杂草是马唐和牛筋草。其出土数量,每平方米少则300—500株,多则2000—3000株。马唐的出土初期为4月底至5月初,出土盛期为5月中旬和6月中旬,出土末期为7月上旬至中下旬。牛筋草的出土初期为立夏以后至6月上旬,出土盛期为6月中旬和7月下旬。两种杂草的出土时间长达100天之久。在棉花 First, the type of cotton weeds and roughly unearthed According to a preliminary survey, Jiangsu cotton coastal cotton weeds, there are more than 10 families, nearly 30 species, of which a long period of occurrence, the occurrence of large, most serious damage to the weeds Crabgrass and tendon grass. The number of unearthed, as little as 300-500 per square meter, as many as 2000-3000. The unearthed Cang Tang early from the end of April to early May, unearthed in mid-May and mid-June, the end of the excavation for early July to mid-late. The early period of the unearthed goosegrass was from the beginning of the summer to the beginning of June, and the peak of the unearthed period was mid-June and late July. Two weeds unearthed for up to 100 days long. In cotton