Weed Survey Just Before Harvest

Survey for weeds just before harvest. Keep records of specific locations in the field where weeds are producing seed. Weed patches are relatively stable within a field and spot treating clusters may improve weed control in future crops.

Depending on harvest date and location, it is possible that you will find winter annuals, summer annuals, and perennial weeds in various stages.

Recording weed survey results assists in weed management decisions, including herbicide choice, cultivation methods, rotational crops, and other cultural practices. Review records from previous crops to determine which weeds may be in the seed bank and require control. Information collected over a period of years shows population changes and the effectiveness of your management operations.

How to survey

  • Walk through each field in a random pattern.
  • Rate the degree of infestation for each weed species on your weed survey form. Use either a numeric scale from 1 to 5 (1 being the lightest, 5 being the heaviest), or rate as "light," "medium," or "heavy."
  • Check fencerows, ditch banks, field edges, and wet spots as these may be problem areas for weed growth and potential sources for wind disseminated seed. Note the dominant species on the monitoring form.
  • Pay particular attention to perennial weeds.
  • Sketch a map of the field and mark areas with major weed infestations for follow-up control action, noting carefully the location of weeds producing seed.
  • Indicate the growth stage of the weed (seedling or mature).
  • Record results on a weed survey form. (PDF)

Important links

PDF: To display a PDF document, you may need to use a PDF reader.

Statewide IPM Program, Agriculture and Natural Resources, University of California
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