Illinois Field Crop Applicators Practice Test

Foliar applied herbicides that require maximum coverage and have fast-developing symptoms are classified as what?

1. Contact

2. Translocated

3. Systemic

4. Selective

The correct answer is: Contact

Foliar applied herbicides that require maximum coverage and exhibit fast-developing symptoms are categorized as contact herbicides. These herbicides work by adhering to and penetrating the target plant's foliage at the site of application. The mechanism of action is immediate, leading to symptoms such as chlorosis or necrosis appearing quickly after application. Contact herbicides are designed to impact only the parts of the plant that are directly exposed, which makes thorough coverage crucial for effective control. This immediate effect is beneficial for managing weeds that are sensitive and can be visibly damaged soon after exposure, thus providing quick results. Translocated and systemic herbicides, on the other hand, are absorbed into the plant and move throughout its vascular system. These may not show symptoms as swiftly since they rely on the plant's physiological processes. Selective herbicides target specific weeds without harming desirable crops, which does not specifically address the requirement of maximum coverage or the speed of symptom development.