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Agronomy QUESTION #2049
Question 1
The critical period of weed competition (CPWC) for most annual field crops refers to:
  • The entire crop growth season during which weeds must be controlled
  • The specific period from crop emergence during which weeds must be removed to prevent unacceptable yield losses, typically corresponding to 25–33% of the total crop growth period✔️
  • The period between planting and first irrigation when weed competition is maximum
  • The post-harvest period when weed seed banks are replenished
Correct Answer Explanation
The CPWC is defined by two thresholds: (1) the period weeds can remain before causing yield loss (weed-free period), and (2) the duration crops must be weed-free after emergence to prevent irreversible yield loss. For most crops it spans 25–33% of the growing period — usually the vegetative to early reproductive stages.