Plant Doctor Archive

Grass grubs

We have large areas (up to 2 sqm) of lawn being dug up I assume by birds. Initially our young border collie was getting the blame but the scratching is too superficial — just enough to kill the grass. We have several patches (7 or 8) on our large lawn and they are unsightly and as we live in a cold winter climate (near Ruapehu) there will be very little growth. Is there anything we can do to prevent the birds from ruining the lawn (other than scarecrows!!)?

How can I get rid and/or stop blackbirds from picking at my grass and destroying it?

The problem is likely to be grass grub. In February/March they feed close to the surface of the lawn causing the dead patches you describe. The birds are looking for grubs.

Diazinon or Soil Insect Killer controls grass grub in lawns and is best applied before heavy rain. It remains within the soil for up to two weeks which is usually long enough to control the grub. Once the grass grub are under control, the birds should stop digging.

Unfortunately, you will need to wait until the ground temperature warms up in spring to resow the bare patches. A cat is a good deterrent.

Advice by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor of Resource Management.

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