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Question

Q

When do I spray my cherry tree to prevent worms?

Answer(s)

A

The best thing to do is to check the USU Fruit Tree IPM(Integrated Pest Management) Advisories that are emailed weekly to subscribers, or you can check online.

To check advisories go to http://utahpests.usu.edu/ipm/htm/advisories/treefruit

To subscribe go to http://utahpests.usu.edu/ipm/htm/subscriptions

As of May 6th advisory, the degree day accumulations in Salt Lake are 500 & 517.  See next excerpt:

The timing of your spray depends on the development
of the fruit. We usually recommend starting applications at
1060 degree days after March 1 (base 41). However, the flies
cannot penetrate the skin of the cherry to lay eggs until the
cherry has developed a salmon-blush color. So use that guideline
for when to start spraying. Check the fruits at the top of
the tree and in the sunniest locations as these will color up
first.

This excerpt came from last year (20080 advisory, go to  http://utahpests.usu.edu/ipm/files/uploads/AdvisoryUpdates/Advisory08/Fruit-IPM-05-28-08.pdf  to see photo of cherry fruit appearance for timing of spray.

So as temperatures go up and degree days accumulate, you'll want to spray at total of 1060, and advisories have that information weekly.

Posted on 14 May 2009

Maggie Shao
Horticulture Agent, Salt Lake County

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