Winter Moth Damage Alert!

Winter Moth Damage Alert!

Attention Cape Cod!

Look closely at your maple, cherry, willow, apple, pear trees and blueberry and rose bushes! It’s likely that when you get up close you’ll see holes and shredded foliage. From a distance it seems like these plants are just still breaking dormancy, but in reality they are being eaten by the larvae of the winter moth caterpillar. These larvae are now growing quickly larger and they are now taking big bites. If you don’t spray your trees quickly you are likely to see them defoliated and weakened. Use Captain Jack’s (spinosad) on any that aren’t flowering and either use Bt (Bacillus thuringiensis) on flowering plants or spray them in the evening when the bees are no longer foraging. (Wet spinosad isn’t good for bees. Once this bacteria is dry it isn’t a problem for bees, but avoid spraying spinosad when bees are on the plants.) 

A cherry tree that was beginning to show signs of damage – this shot from a property in Mashpee.
If you part the leaves that are stuck together with webs, you'll see the green larvae.
If you part the leaves that are stuck together with webs, you’ll see the green larvae.
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  1. Kenneth falletti on May 20, 2015 at 8:21 pm

    Thanks for the heads-up, my blackbirds birch and blueberry Bush seem to have these symptoms. Captain Japtain Jack it is! Thanks for tip sincerely, Ken Falletti May 21,2015

  2. Joe Denaro on May 21, 2015 at 9:10 pm

    While I appreciate this ALERT, it’s about two weeks too late. My ornament cherry/pear trees have flowered already and the leaves are being consumed as I click…..

    • CLFornari on May 21, 2015 at 9:36 pm

      If you sprayed them tomorrow what foliage remains would be protected…

  3. Rhonda on May 22, 2015 at 7:57 am

    Can I spray my roses with captain jacks. They are just budding now, but not blooming yet? Or do I need to get bt?

    • CLFornari on May 22, 2015 at 9:28 am

      Yes, Rhonda, you can use the Captain Jack’s safely on budded roses. Good to get them sprayed now because that will not only protect against winter moth larvae but also the rose-slug budworm, which always follows the winter moth.

  4. Carol Peterson on June 4, 2015 at 9:34 am

    How do I “nip this in the bud” next year?

    • CLFornari on June 4, 2015 at 11:03 am

      Good question, Carol! Here’s what people can do: Make a note of the plants that got eaten this year and write the list on your calendar for next year in April. Put down something like “Keep checking maples, cherry and birch for signs of tiny holes.” Wintermoth larvae can hatch in March or later in April, depending on the temperatures. There is some thought that the hatching occurs at the same time as the Pieris (aka Andromeda shrubs) bloom, so if your Andromeda is in full bloom it’s likely that it’s time to spray Captain Jack’s Brew on plants that are prone to damage. If you spray when the leaves are first opening, you’ll get many of the larvae when they are very small. Then repeat at least once a couple of weeks later when the leaves are larger – a third application when the leaves are almost full-sized can also be useful. The key is to start before the larvae are large, because when they are small they are taking tiny bites but once they get large they can defoliate a tree or rose bush pretty quickly.

  5. Nancy Hunter-Young on June 11, 2015 at 3:07 pm

    Thanks for the helpful info about Captain Jack’s. Is this product safe to use on my ornamental cherry and my roses in our yard where two dogs are constantly about (playing, sleeping, eating grass, and other dog mischief!)?

    • CLFornari on June 11, 2015 at 3:55 pm

      Yes, this product is safe to use where the dogs are hanging out. It is a natural bacteria and does not harm dogs, birds etc.

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