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Orchard and dormant branch to be sampled for aphid eggs.


Dormant Spur Sampling

Dormant spur samples are taken once a year to determine the need for a dormant treatment to control San Jose scale, European red mite, brown mite, and European fruit lecanium. Spurs are the short shoots containing the flower buds.

When and how to sample:

  1. Take a sample between mid-November and mid-January.
  2. Randomly select 35 to 50 trees from each orchard or plot to be sampled.
  3. Choose 2 to 3 spurs randomly from the inside of each tree's canopy near the main scaffold for a total of 100 spurs.
  4. Clip the spur off at the base, making sure to include some old spur wood along with the past season's growth to detect parasite activities on scales.
  5. Using a hand lens or binocular microscope, examine 20 of the spurs and note the presence or absence of mite eggs and live parasitized scales on the dormant spur sampling form (136 KB, PDF). It is not necessary to count the number of individual insects or mite eggs present.

If a large number of scales have been parasitized, minimize the use of insecticides during the growing season, and use those that are not harmful to parasites so that naturally occurring parasite populations will not be destroyed.

Treatment thresholds

  • When comparing samples to treatment thresholds, do not combine totals for the two scale species. For example, if 3 spurs out of a sample of 20 are infested with San Jose scale and 3 spurs contain European fruit lecanium, neither has exceeded the threshold and sampling should continue.
  • If no scale or mite eggs are found in the initial sample of 20 spurs, stop examining spurs. There is no need to treat.
  • If 1 to 3 spurs are infested with scale, examine the next 20 spurs. Continue examining spurs until a decision is made to treat or not to treat using the treatment guidelines on the sampling form.
  • If 4 or more spurs are infested with live scale, apply a treatment.
  • Treat for brown mite and European red mite if 20% or more spurs are infested.

See the pest management guideline for more information about treatment choices according to infestation levels.

Important links

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