Illinois Field Crop Applicators Practice Test

Which factor improves herbicide effectiveness and aims to decrease drift?

1. Reducing soil moisture

2. Addition of adjuvants

3. Decreasing temperature

4. Increasing rainfall

The correct answer is: Addition of adjuvants

The addition of adjuvants is a key factor that enhances herbicide effectiveness while also aiming to reduce drift. Adjuvants are substances that modify the physical and chemical properties of herbicides, improving their ability to penetrate plant surfaces, enhance adherence, or improve the spread across the leaf surface. This modification can lead to better absorption of the herbicide by the target weeds, which increases efficacy. Moreover, certain types of adjuvants can help to reduce the droplet size and improve the uniformity of the spray pattern, which is particularly beneficial in minimizing drift. By reducing drift, adjuvants ensure that more of the herbicide reaches the intended target area rather than dispersing into the environment, which could harm non-target plants or contribute to environmental contamination. In contrast, factors such as reducing soil moisture, decreasing temperature, or increasing rainfall do not inherently improve the effectiveness of herbicides in the same way adjuvants do. Reduced soil moisture can lead to decreased herbicide activation in the soil, while decreased temperature typically slows down plant processes, potentially affecting herbicide uptake and activity. Increased rainfall may lead to herbicides being washed away before they can be adequately absorbed or may dilute their concentration. Hence, the role of adju