Ornamental and Turf Pesticide Applicators Practice Exam

Which factor enhances the effectiveness of post-emergence herbicides?

1. Availability of moisture in the soil

2. Low soil temperature

3. High stress conditions for plants

4. Application during early morning hours

The correct answer is: Availability of moisture in the soil

The effectiveness of post-emergence herbicides is significantly enhanced by the availability of moisture in the soil. When soil moisture levels are adequate, it promotes better absorption and translocation of the herbicide within the target plants. This is essential for ensuring that the herbicide can move throughout the plant tissues to where it can act on the intended target, leading to more effective weed control. Moist soil conditions can also enhance the growth and metabolic activity of the weeds, making them more susceptible to the effects of the herbicides. In contrast, low soil temperature can slow down the plants' metabolic processes, potentially reducing the absorption and efficacy of the herbicide. High stress conditions for plants, such as drought or extreme temperatures, can lead to reduced herbicide uptake. Applying herbicides during the early morning hours may offer some benefits in terms of environmental conditions, but moisture availability is a more critical factor in improving the overall effectiveness of post-emergence applications.