Grub damage or not?

Discussion in 'Landscape Maintenance' started by lewdo, Mar 13, 2009.

  1. lewdo

    lewdo LawnSite Member
    Messages: 86

    Last fall around mid October I noticed areas in a customers yard were the turf had been pulled back. Other areas I could pull the turf right up. Sounds like classic examples of grubs. Only thing was I couldn't find any. At least not enough to cause that type of damage. I've read it takes like 10-12 per square foot to cause this type of damage. Is there another insect, animal or fungus that could cause the same damage. Thanks.

    MOW PRO LAWN SERVICE LawnSite Bronze Member
    Messages: 1,568

    Most common grubs,or heat/drought damage,hard to tell without looking @ it...............
  3. gandk06

    gandk06 LawnSite Senior Member
    Messages: 509

    I have seen that same problem around here. 9 times out of 10 it is skunks digging up the yard going after the grubs. Can't remember off the top of my head which product I used from Lesco to get rid of the grubs and in turn get rid of the skunks but it worked very well.
  4. Eden's Own

    Eden's Own LawnSite Member
    Messages: 38

    You are not going to see any grubs in October as they are likely in their adult stage and no longer feeding on the roots of turf and more likely feeding on ornamentals. Mach 2 or Merit are probably the best treatments for grubs, but you have to treat when they are in the larval stage and actively feeding on the roots.
  5. Whitey4

    Whitey4 LawnSite Silver Member
    Messages: 2,448

    Grubs will feed through October, and they sure as chit aren't eating ornamentals... sorry, but that is just a clueless statement.

    Just to be clear... beetles lay eggs in July and August. Two weeks after they lay eggs after mating, the first instar grub larvae hatch. The adults die after mating. There are no adults in Ocotber. Grubs will continue to feed and go into their 2nd and 3rd instar before winter. Once it becomes cold, they will over winter below the frost line. In the spring, they re-emerge and feed on turf roots, go into the 4th and 5th instar, emerge as flying beetle adults, and mate. Only the Japanese beetle feeds as an adult. The other types do not.

    How cold was it when you inspected the turf? Was it after the first or second frost? Often grubs will move from the really badly damaged turf to find healthier root systems to feed on. Look at the turf nearby when inspecting, at the apparently healthier turf.

    The best time to treat for grubs is in the first or second instar. That means applying controls in August in most northern zones. You can try to treat in the spring, but the 4th instar stage means more mature larvae, and much tougher to kill. Those that do survive treatment may lay eggs that are more pesticide resistant.

    The Cornell cooperative extension says more than 6 or 7 grubs in a square foot of turf is the treatment guideline. I would look again in the spring when they re-emerge from over wintering. If you count 7 in a foot, treat in the spring at the max rate allowed by label. Be sure to re-apply in August in a known infestation area. Try to use a different pesticide on that second round. Maybe Merit in round 1, Dylox in round 2 in August. Merit should be more effective on the late instar grubs in the spring, while the Dylox should take out the young grubs in the 1st or 2nd instar.

    You might also try the floatation test. Get one of those large coffee cans, take both ends off. Using a knife to score the turf, sink the can into the turf about 3 to 4 inches deep. Fill the can with tepid (luke warm) water. Wait 10 minutes. If the water starts to drain out, add a little more gently.

    If it is chinch bugs, they will float (even swim) to the top. Chinch bug damage can look very much like grub damage, but the pesticide to be used is different for these pests. Chinch bugs will also over winter in turf. Know the enemy, and then know how to kill it. And of course, I have to say, be legal for pesticide applications in your state when doing pest control on customer properties.
  6. foreplease

    foreplease LawnSite Silver Member
    Messages: 2,052

    That is for sure.

    I would add (and am sure Whitey4 is assuming): whichever appropriate product you use at the then appropriate time, it must be watered in well.
    I believe there are only three instar stages though.

    As far as lewdo not finding any at that time of year, my guess is either the skunks ate those in the area he examined or the grubs were deeper in the soil than he looked. We can't treat on that assumption, of course, we would need to get a good count.

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