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  • Japanese beetle grubs and nematodes

    Created by Mary Clark on

    Hello –

    I just planted my garden, but while I was planting I noticed several white grubs which I believe are Japanese beetle larvae as we had a large infestation of them last year. I’m not sure if I should distribute nematodes now or wait til plants come up. I have tomato and pepper plants out now, but planted several varieties of squash and cucumber seeds directly into the ground. Also corn. Should I buy nematodes now or wait? Or is that my best choice?

    Thanks, Mary

  • Author
  • #237181

    Eric Vinje

    Hi Mary –

    To combat Japanese beetles, apply Scanmask® Beneficial Nematodes by hand as a topdressing, or add to seed furrows and around transplants. Concentrate applications to areas with signs of damage and areas in full sun. Treat drip zones of shrubs and trees. Apply in early spring or fall — one pack will treat 510 square feet.

    Other organic and natural methods for getting rid of Japanese beetles include:

    • In the early morning or late evening, shake beetles from plants onto ground sheets and destroy.
    • Place pheromone traps around the perimeter of your property as adults emerge (May-July).
    Floating row cover (Harvest-Guard®) can be used as a physical barrier to prevent adult beetles from damaging plants.
    Milky Spore (Bacillus popilliae) is a naturally occurring host specific bacterium that attacks the destructive white grubs in turf. Apply 10 oz per 2,500 sq ft anytime of year when the ground is NOT frozen.
    Surround WP (kaolin clay) forms a protective barrier film, which acts as a broad spectrum crop protectant for preventing damage from a large number of insect pests.
    Azatrol EC contains azadirachtin, the key insecticidal ingredient found in neem oil. This concentrated spray is approved for organic use and offers multiple modes of action, making it virtually impossible for insect resistance to develop. Best of all, it’s non-toxic to honey bees and many other beneficial insects.
    • As a last resort, spot treat adults with botanical pesticides. Apply to all leaf surfaces and deep into the plant canopy where insects hide.

    Good luck!

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