When is the best time to apply pre-emergent herbicide for cool season crops?

The best time to apply pre-emergent herbicide for cool season crops is in spring. This timing is crucial because pre-emergent herbicides work by preventing the germination of weed seeds. For cool-season crops, these weeds often begin to germinate as soil temperatures rise in spring, typically when soil temperatures reach around 50-55°F (10-13°C). By applying the herbicide at this time, you can effectively inhibit the establishment of these weeds just as they start to emerge, ensuring that the cool-season crops have a better chance to thrive without competition.

In contrast, fall applications can sometimes be too early for controlling spring-germinating weeds and may not provide effective protection. Winter and summer applications are also unsuitable; winter conditions can prevent the herbicide from acting effectively, and summer is often outside the target growth period for cool-season weeds. Thus, spring application aligns perfectly with the seasonal growth patterns of the weeds you aim to control in conjunction with the planting schedule of cool-season crops.