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sod with grub damage
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Keep your turf grub free!


All of a sudden, my lawn is getting all of these small holes, about the size of a lemon, dug all over. I had been told that we did not have Japanese beetles, so I don't think that the grubs are the problem. Off to one side, there is an area where the sod was just totally peeled back. What is causing all of the damage, and how do I stop it from happening?

Answer

Despite the fact that you were told you did not have Japanese beetles; I am virtually positive judging by the visual image I inspected and the timing of this occurrence that it is grub damage. Grub worms are the result of primarily Japanese beetles, also called European chafers, laying their eggs around midsummer, preferentially in sunny locations on your lawn. The white grubs are the larval form of these scarab beetles and will begin feeding on lawn roots. Grub damage will then typically become visible around late summer showing itself as brown, patchy and unattractive lawn areas. Such visual scarring could however also be due to other causative factors, i.e. poor soil, drought or disease. One should always physically search for grubs by looking beneath the turf. Once grubs reach levels of 8-12 per square foot they will cause damage. Though grubs themselves do eat grass roots and cause damage this way, oftentimes the more severe damage will occur when further wildlife comes to eat the grubs. These will commonly be raccoons or skunks, sometimes moles and birds, and they will dig into the turf to reach the grubs, at times peeling off entire sections of turf.

Mechanical Control

Performing routine cultivation and lawn aerating can be minimally successful.

Biological Control

Beneficial nematodes are environmentally friendly as they will attack grubs and are not harmful to bees, earthworms or other beneficials. The same applies for Milky Spore, a nodual bacteria. Nematodes can be applied by means of watering, injection or by mixing them in with soil or mulch, whilst the Milky Spore is applied in a granular form. The bacteria remain dormant in the soil until ingested by grubs, at which time it multiplies and subsequently consume the grub. Grub Busters Grub Eliminator would be an effective nematode product. Both biological control forms should be repeated for several years.

Chemical Control

Effective chemical treatments include the active ingredient chlorantraniliprole or dylox. Products containing dylox are applied in midsummer and kill mature grubs upon contact which are feeding beneath the soil surface. However as dead grubs remain present in the soil for some time damage can still occur from raccoons and skunks digging for these. On the other hand chlorantraniliprole products can be applied earlier in the summer before grubs have hatched. Newly hatched grubs are highly susceptible and are thereby reduced before causing excessive damage. Examples of these would be Bayer 24 Hour Grub Killer Plus and Scott's Grubex.



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