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Walnut

Seedling of California burcloverWinter Weed Survey

Survey for weeds in January or February to determine which winter weed species are emerging. You can use this information to make weed management decisions such as herbicide choice or cultivation practices.

Ideally, tree rows are weed free. Weeds growing in row middles may be beneficial in reducing erosion, soil compaction, and water and sediment runoff. However, perennial weeds are difficult to control and should be kept from establishing in row middles. Winter cover crops will reduce surface water runoff (minimizing off-site movement of pollutants), reduce perennial weeds, and improve water penetration.

How to survey your orchards

  • After the first fall rains, look for winter annuals seedlings in tree rows to check the effectiveness of any
    preemergent herbicide applications.
  • If you use cultivation for weed control, monitor at least 2 weeks before you plan to cultivate.
  • Check the groundcover in row middles for perennial seedlings. Check for regrowth of perennials a few weeks after cultivation.
  • Sketch a diagram of the orchard and mark areas where perennials are found.
  • Indicate the growth stage of the weed on the form (seedling or mature).
  • Rate infestation either using a numeric scale from 1 to 5 (1 being the lightest), or using "light," "medium," or "heavy."
  • Record your results (sample winter weed survey form114 KB, PDF).

Survey information collected over a period of years tells you how weed populations change and how effective your management operations have been over the long term. Keep these records so that you can track weed populations from year to year to better understand ongoing weed control problems such as resistance.

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