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Japanese beetle grubs

Discussion in 'Pesticide & Herbicide Application' started by Yatt, May 9, 2013.

  1. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    That is what I used on the giant moles in FL... I'll have to see if they are small enough for the common mole around here... :)

    METRO FS LawnSite Member
    Messages: 48

    You're on the right track Yatt as both are excellent traps.
  3. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,727

    As is often the case--your customer has two problems. He wants to get rid of any grubs present NOW. So you have to check the soil, and determine if grubs are present now--as a professional--this is the first step. Usually they are not worth treating, as they will pupate soon and re-emerge from the ground as adult Japanese beetles...and fly away. BUT if you wish you can use Dylox; it kills in one day, but only lasts about 5 days.

    BUT then your customer needs the preventative treatment with Merit during the July egg-hatch period. Merit in July protects against the newly hatched grubs that would otherwise grow, molt into 3 larger instars and cause damage in September and October. Merit in July protects against grubs until the following July, which is when new eggs could be laid by the adult flying beetles. Grubs cannot come in to the yard from next door; their legs are short; they don't travel far.

    In most cases, grass can tolerate a high level of grubs... if... it is well-watered.

    Skunk damage is one of the most reliable signs of grub infestation. Flocks of birds also love to feed on grubs in the fall. Their beaks leave distinctive round holes in the turf.

    Beetle traps for Japanese beetles (as you mentioned) make the problem worse by attracting beetles from 1000 feet away, but once attracted, most lay their eggs near the traps...and only a few enter the traps...and are caught.

    Moles are a separate problem; they eat mostly worms. Use traps or a poison bat like Talpirid.
  4. Yatt

    Yatt LawnSite Member
    Messages: 203

    Hi Riggle,

    I was over with the landowner this morning and dug two 1 foot square test patches. Found one grub that sure sounds like a japanese beetle grub and not the very large June bug, (pinching beetle). It may be still a little early for them to approach the surface and start the cycle over. The yard has filled in well since last fall since it has rained 16" so far this year and is raining as I type. The 33-0-5 fertilizer with 2% iron, 100% controlled release Nutrisphere is working excellent.

    So we will monitor and if the grubs are bad, I will apply Merit laced fertilizer, other wise I'll stick with the 33-0-5.

    I took him over a height gauge for setting his mower as it is cutting way to short. He said no it's set at 4". So I checked, it was at 1.5":dizzy:

    So he is getting out the manual on adjustment, it's a New Holland small diesel and the deck raises/lowers off the 3 point in the back.
  5. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,727

    Hi Yatt,
    Here is information on identification of the species of grub. You need a magnifying glass or a 10x naturalist's lens to check the raster pattern. It is best to know which kind of grub you have.

    I am sure you have seen plenty of Japanese beetles eating apple trees, rose bushes, and linden trees. Around here the Japanese beetle adults appear about July 15. European chafer adults appear only at dusk and sometimes cluster around lights, seldom seen unless you are looking for them.
    If you know which kind of grubs you have--you are better able to time the applications to get the best control. And then you will be more informed and more professional than TruWean.

    Sigh! So true...lots of homeowners think that one notch on their mower equals one inch--its often a half inch.
    Last edited: May 30, 2013
  6. phasthound

    phasthound LawnSite Fanatic
    Messages: 5,149


    Tell your client to relax, one grub/2 sq ft is not a problem.

    In fact such a low population is beneficial as it will support a healthy population of predators which will feed of existing grubs, keeping them below the damage threshold. Treating for grubs now would be counter productive.

    And congratulations on correcting the mower setting for him!
  7. Yatt

    Yatt LawnSite Member
    Messages: 203

    Well I've got 55 apple trees in my backyard. I don't get many Japanese beetles. Of course a dose of 1# Imidan every 14 days may be the reason for that (calculted on 1 acre).:laugh:
  8. Yatt

    Yatt LawnSite Member
    Messages: 203

    I think I talked him out of putting out the japanese beetle traps. I have one other client that I have been after also about mower heigth. She too has about the same kind, a sub compact utility tractor and she swore it was cutting at 4". I measured and that one too was at about 2.5" and the setting knob said 4".

    So the first instar grubs appear about the middle of July?

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