Agronomy Pest and Weed Management 1 — Questions and Answers
Question 1: What is Integrated Pest Management (IPM)?
- Using only chemical pesticides to control pests
- A strategy combining biological, cultural, mechanical, and chemical controls to minimize economic damage (Correct answer)
- Eliminating all insects from a field
- Relying solely on resistant varieties
Correct answer: A strategy combining biological, cultural, mechanical, and chemical controls to minimize economic damage
IPM uses a combination of methods—biological, cultural, mechanical, and chemical—to manage pests economically while minimizing environmental impact.
Question 2: What is an 'economic threshold' in pest management?
- The cost of applying a single pesticide application
- The pest density at which control action must be taken to prevent economic loss (Correct answer)
- The maximum legal pesticide residue level
- The number of pests that can be controlled per dollar spent
Correct answer: The pest density at which control action must be taken to prevent economic loss
The economic threshold is the pest population level at which the cost of crop damage equals the cost of control, triggering a management decision.
Question 3: Which weed management practice uses crop competition to suppress weed growth?
- Post-emergence herbicide application
- Increasing crop seeding rate and narrow row spacing (Correct answer)
- Fallowing
- Hand weeding
Correct answer: Increasing crop seeding rate and narrow row spacing
Increasing seeding rate and using narrow rows promote faster crop canopy closure, shading weeds and limiting their access to light and resources.
Question 4: Palmer amaranth is considered one of the most problematic weeds in US row crops primarily because of what?
- It is a C3 plant with slow growth
- It has evolved resistance to multiple herbicide modes of action and grows extremely fast (Correct answer)
- It only affects organic fields
- It produces few seeds per plant
Correct answer: It has evolved resistance to multiple herbicide modes of action and grows extremely fast
Palmer amaranth grows up to 2–3 inches per day, produces hundreds of thousands of seeds, and has developed resistance to herbicides including glyphosate.
Question 5: What does 'mode of action' refer to for a herbicide?
- The chemical formulation of the product
- The biochemical pathway or enzyme in the plant the herbicide disrupts (Correct answer)
- The application timing relative to crop emergence
- The physical form of the herbicide (liquid vs. granule)
Correct answer: The biochemical pathway or enzyme in the plant the herbicide disrupts
A herbicide's mode of action describes the specific site (enzyme, protein, or process) in the plant that it inhibits to cause plant death.
Question 6: European corn borer (ECB) larvae cause the most damage to corn at which crop stage?
- At emergence (VE)
- During rapid vegetative growth and early reproductive stages (V6-R1) (Correct answer)
- At physiological maturity
- During germination
Correct answer: During rapid vegetative growth and early reproductive stages (V6-R1)
ECB larvae feed on whorl leaves, then bore into stalks and ears during the vegetative and early reproductive stages, causing the greatest economic damage.
Agronomy Pest and Weed Management 1
What is Integrated Pest Management (IPM)?