Abstract
In field experiments during 1975 to 1977 the final yield of cucumbers (Cucumis sativus L. ‘Salty’) was unaffected when a naturally occurring weed infestation remained in the plots for the first 12 days after emergence in 1975 and for the first 24 days in 1976 and 1977, provided the crop was kept weed-free subsequently. If the cucumbers were kept weed-free for the first 12 days after emergence in 1975, 24 days after emergence in 1976, and 36 days after emergence in 1977, there was no loss of yield caused by weeds that emerged later in the season. The critical period of weed interference was therefore between 12 and 36 days after crop emergence. In other experiments, cucumber yields were reduced significantly when only 5% of the weeds were allowed to remain in the plots longer than 24 days after crop emergence. The percentage of various commercial grades, based on cucumber size, was not altered by weed interference and appeared to be dependent on harvesting frequency.