Integrated Pest Management (IPM) in Weed Science — Crop Protection Reviewer Questions

250 board-style Integrated Pest Management (IPM) in Weed Science items for the Agriculturist Licensure Examination, free and open to every examinee. Group pesticides by mode of action rather than by trade name. The examination asks about resistance management far more often than about products.

250 built-in questions in this topic · approved additions may publish live · part of Crop Protection

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Sample Integrated Pest Management (IPM) in Weed Science questions with answers and explanations

Board-style items taken from the Crop Protection bank. Every answer is explained, which is the part that makes a review question worth doing twice.

A Nueva Ecija rice farmer wants a weed-free field even though the remaining weeds are sparse, below the level that affects yield, and provide some habitat for beneficial arthropods. Under integrated weed management, what is the best decision?
- A. Stop additional control unless monitoring shows the weeds are approaching an economic or critical threshold. correct
- B. Apply another herbicide immediately to achieve 100% weed mortality.
- C. Cultivate the entire field repeatedly until no weed propagules remain.
- D. Burn all field borders to eliminate every non-crop plant.
Why: Integrated weed management aims to keep weeds below damaging thresholds, not necessarily to eradicate every plant. Extra control below threshold can add cost and environmental risk without a yield benefit.
A corn field in Bukidnon has itchgrass, purple nutsedge, and broadleaf weeds. The farmer has relied on one post-emergence herbicide for several years. Which redesign best reflects integrated weed management?
- A. Increase only the dose of the same herbicide each year.
- B. Combine crop rotation, stale seedbed or cultivation, competitive crop establishment, sanitation, and herbicides with different effective modes of action. correct
- C. Use hand weeding alone regardless of labor availability and weed biology.
- D. Delay all weed control until weeds are flowering so they are easier to identify.
Why: IWM combines preventive, cultural, mechanical, biological/ecological, and chemical tactics so that no single tactic carries the whole selection pressure.
A farmer notices that a low-density weed species produces thousands of persistent seeds per plant. Which threshold strategy is most appropriate for long-term management?
- A. Use a higher threshold because low density always means low future risk.
- B. Ignore the weed until the next crop because seed production affects only the current season.
- C. Use a lower action threshold for that species because allowing seed production can rapidly enlarge the soil seedbank. correct
- D. Treat only after the crop is harvested, when competition has ended.
Why: The module notes that species producing tremendous numbers of propagules should be allowed a much lower threshold in long-range weed management.
Two neighboring rice fields have the same weed density, but one is direct-seeded and the other transplanted. Which management interpretation is most defensible?
- A. Both fields must have exactly the same critical period because the crop species is the same.
- B. The transplanted field always needs more herbicide because older rice is more sensitive to weeds.
- C. Weed density alone is sufficient; establishment method does not affect crop competitiveness.
- D. The direct-seeded field may require earlier or more intensive control because rice and weeds emerge together and the crop has less initial size advantage. correct
Why: Direct-seeded rice commonly experiences stronger early weed competition because weeds and rice establish simultaneously, whereas transplanted rice has a head start.
A vegetable farmer can afford only one major weed-control operation. Field scouting shows rapid weed emergence during the crop's early vegetative stage. When should the operation be prioritized?
- A. During the crop's critical period of weed competition, before early interference causes irreversible yield loss. correct
- B. Near harvest, because large weeds are easier to see.
- C. After weeds have set seed, so all cohorts can be treated at once.
- D. Only during land preparation, regardless of later emergence.
Why: The value of weed control is greatest during the critical period when the crop is most sensitive to interference.
After several seasons of excellent grass control in rice, sedges and broadleaves become dominant. What is the most appropriate IWM response?
- A. Continue exactly the same program because the original target grass is controlled.
- B. Reassess the weed community and diversify tactics so control does not continue selecting for a harder-to-manage species shift. correct
- C. Increase nitrogen fertilizer so rice can outgrow all weeds.
- D. Eliminate crop rotation to keep management simple.
Why: A good weed-management program should avoid shifting the community from one noxious weed to another more difficult species.
A farmer asks whether an IWM program has failed because a few weeds remain after treatment. Which field criterion best answers the question?
- A. Count only the number of visible dead weeds 24 hours after spraying.
- B. Judge success only by whether the field looks completely bare between rows.
- C. Evaluate crop yield, weed density relative to thresholds, seed production, cost, and future seedbank risk rather than demanding zero weeds. correct
- D. Assume any surviving weed proves the program is ineffective.
Why: IWM performance is based on economically and ecologically acceptable suppression, not cosmetic eradication.
A rainfed rice farmer expects labor shortages during the wet season. Which plan is most resilient?
- A. Wait for labor to become available even if the critical period has passed.
- B. Use only late-season hand pulling after panicle initiation.
- C. Apply fertilizer first and postpone weed control until weeds become taller than rice.
- D. Use prevention and cultural practices early, then schedule mechanical or label-approved herbicide control before the critical period rather than relying on delayed hand weeding. correct
Why: Rain can delay hand weeding; integrating tactics before the critical period reduces the risk of missing the biologically important window.

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Integrated Pest Management (IPM) in Weed Science — Crop Protection Reviewer Questions

Sample Integrated Pest Management (IPM) in Weed Science questions with answers and explanations

A Nueva Ecija rice farmer wants a weed-free field even though the remaining weeds are sparse, below the level that affects yield, and provide some habitat for beneficial arthropods. Under integrated weed management, what is the best decision?

A corn field in Bukidnon has itchgrass, purple nutsedge, and broadleaf weeds. The farmer has relied on one post-emergence herbicide for several years. Which redesign best reflects integrated weed management?

A farmer notices that a low-density weed species produces thousands of persistent seeds per plant. Which threshold strategy is most appropriate for long-term management?

Two neighboring rice fields have the same weed density, but one is direct-seeded and the other transplanted. Which management interpretation is most defensible?

A vegetable farmer can afford only one major weed-control operation. Field scouting shows rapid weed emergence during the crop's early vegetative stage. When should the operation be prioritized?

After several seasons of excellent grass control in rice, sedges and broadleaves become dominant. What is the most appropriate IWM response?

A farmer asks whether an IWM program has failed because a few weeds remain after treatment. Which field criterion best answers the question?

A rainfed rice farmer expects labor shortages during the wet season. Which plan is most resilient?

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