Lecture 7 Factor affecting crop-weed competition
Factor Affecting Crop-Weed Competition 1. Period of weed growth ü Weeds interfere with crops at any time they are present in the crop. Thus, weeds that germinate along with crops are more competitive. ü Sugarcane takes about one month to complete its germination phase while weeds require very less time to complete its germination. By that time crop plants are usually smothered by the weeds completely. ü First 1/4 - 1/3 of the growing period of many crops is critical period. ü In direct sown rice more severe weed competition than transplanted rice. However, in a situation, where weeds germinate late, as in dry land wheat and sorghum, the late-stage weeding is more useful than their early weeding. ü In general, for most of the annual crops first 20-30 days weed free period is very important. 2. Weeds / Crop density ü Increasing weed density decreasing the crop yields. ü In rice density of Joint vetch ( Aschynom...