Herbicide Timing & Effects Quiz Quiz

Explore key concepts related to the proper timing and effects of herbicide application in agriculture, with realistic field scenarios and explanation of best practices.

1. Pre-Emergence Herbicide Application

   Which is the primary purpose of applying a pre-emergence herbicide to a corn field before seeds sprout?

   1. To improve crop seed vigor
   2. To increase soil moisture levels
   3. To fertilize the crop directly
   4. To prevent weed seeds from germinating

   Explanation: Pre-emergence herbicides are designed to control weeds by inhibiting their germination and early growth, giving crops a competitive advantage. They do not directly affect soil moisture, seed vigor, or act as fertilizers. Their main benefit comes from targeting weed seeds at the soil surface.

2. Selective vs. Non-Selective Herbicides

   A farmer wants to remove all plant growth from a field before planting a new crop. Which type of herbicide should they consider using?

   1. Fungicide
   2. Insecticide
   3. Selective herbicide
   4. Non-selective herbicide

   Explanation: Non-selective herbicides kill most plant types, making them suitable for clearing all vegetation prior to planting. Selective herbicides target specific plants, fungicides control fungal diseases, and insecticides control insects, none of which achieve complete plant removal.

3. Weather Impact on Application

   Why should a grower avoid applying herbicides immediately before a heavy rain is forecast?

   1. It increases the risk of herbicide runoff
   2. It improves soil structure
   3. It enhances herbicide absorption in weeds
   4. It ensures more uniform seedling emergence

   Explanation: Heavy rainfall can wash away applied herbicides, causing environmental contamination and reducing effectiveness. Enhanced absorption, improved soil structure, or uniform emergence are not outcomes of applying herbicide before rain and may even be negatively affected.

4. Resistance Management

   What is a recommended strategy to minimize herbicide resistance developing in weed populations?

   1. Always using the same product each year
   2. Rotating herbicide modes of action
   3. Applying only pre-emergence herbicides
   4. Increasing herbicide rates above recommended levels

   Explanation: Rotating herbicide modes of action attacks weeds in different ways, reducing the risk of resistance developing. Only using pre-emergence herbicides, increasing rates, or repeatedly using the same product may actually encourage resistance or violate best practices.

5. Impact on Non-Target Species

   What is a key environmental concern when herbicides are improperly applied or drift into nearby areas?

   1. Decreased sunlight intensity
   2. Enhanced microbial diversity
   3. Damage to non-target crops and plants
   4. Increased crop pollination rates

   Explanation: Herbicides drifting from the intended area can harm nearby plants and sensitive crops. These chemicals do not decrease sunlight, enhance microbes directly, or increase pollination, making non-target plant damage the primary concern.