Weed Seeds This Fall Mean More Weeds Next Spring

By Dwight Lingenfelter

Now is the time to think about controlling summer annual weeds prior to seed set in cropping situations where possible. Preventing seed production is important for driving down the weed seed bank and reducing the need for weed control inputs (i.e., herbicides). It is rather easy to prevent weed seed production following a cereal grain such as wheat, barley, or oats, as well as some vegetable crops such as sweet corn or snap beans. Proper timing of the control practice is essential in preventing seed production. In general, below is a summary of estimated seed drop for various weed species:

• Giant foxtail: late August and peak seed rain usually occurs from late September through the month of October
• Yellow foxtail: early August and continues into late October
• Pigweed species: begin to produce mature seed by mid-August
• Lambsquarters and ragweed: generally, do not mature until the month of September