The critical period for weed control in safflower fields of turkey

Crop-weed competition is among the most significant topics in field crops if the crop is a weak competitor in this rivalry. Safflower is a valuable oil seed crop that is drought tolerant and used as a raw material in the food and biofuel industries. Although it has good drought tolerance, it is a sensitive crop against weed competition, especially wild mustard. The critical period for weed control (CPWC) is a useful tool to decide which time period is more suited for weed control economically. In this study, the beginning and end of the CPWC were determined for the summer safflower fields of Turkey. Weeds caused 50.61, 65.87, and 63.34% safflower yield reductions in 2017, 2018, and 2019, respectively. The beginning of the CPWC was 165, 198, and 225 air growing degree days (air GDD) for these years, while the end of CPWC varied 1348, 1837, and 2268 at 5% acceptable yield loss.