Illinois Pesticide Applicator Practice Test

Pesticide failure can be caused by which of the following factors?

1. Pest resistance

2. Inappropriate rate of pesticide used

3. Environmental factors unfavorable for pesticide activity

4. All of the above

The correct answer is: All of the above

Pesticide failure can occur due to a combination of several factors, which is why the most comprehensive answer includes all options. Pest resistance is a significant issue where certain pests may develop a tolerance to specific pesticides over time due to selective pressure. This resistance means that even if the pesticide is applied correctly, it may not effectively control the target pest population. Using an inappropriate rate of pesticide can also lead to failure. If a pesticide is applied at a rate that is too low, it may not provide adequate control, while using a rate that is too high might lead to phytotoxicity, environmental harm, or the development of resistance. Environmental factors play a critical role as well. Conditions such as temperature, humidity, and the presence of sunlight can influence the efficacy of a pesticide. For example, high temperatures might cause the pesticide to evaporate too quickly, while heavy rain shortly after application could wash the pesticide away before it has time to work. Each of these factors can critically influence the success of pest management practices, making "all of the above" the correct and most comprehensive answer.