In many plants, seed germination and seedling emergence respond to environmental cues (such as soil temperature or moisture) that indicate favorable growth conditions.

Therefore, the timing of weed management can influence weed control efficacy and weed community composition.

Weed Seed Germination Time

Proportion of weed seeds germinating throughout the season in central Pennsylvania.

Spring and Fall Tilled

Timing of cover crop termination can also have a strong influence on weed abundance in the following crop. In the photograph below, the plot on the right was tilled and planted to soybean several weeks earlier than the plot on the left. Delaying planting improved the effectiveness of pre-plant cultivation, which reduced weed density.

Soybean Delayed Planting