One of the most common turf maintenance hurdles is keeping lawn pests, or lawn grubs, at bay. There are two common lawn grubs which you should look out for on your lawn:
- Armyworms – These are dull grey or brown worms that look like caterpillars and are mostly active at night. They are especially deadly, and they can destroy your entire lawn within a few nights!
- Sod webworms – These are transparent worms (they may appear greenish because of the materials they ingest) that are smaller than armyworms.
How to detect lawn grub infestation
The following symptoms may indicate grub infestation:
- Examine your lawn for thinning turf or brown patches on turf – there may be other reasons, but grub infestation is likely if other symptoms are also present.
- Inspect a leaf blade from the thinning or browning patch. You'll notice chew marks or holes on the blade. If infestation is more advanced, most of the blade will be missing
- If you connect a water hose and flood your lawn, you'll notice the worms moving up the leaf blades to avoid drowning. Don't do this on the browning patch, since they've probably moved to a much greener area already. Choose the greenest patches and work your way through the entire lawn.
- You can also pour a bucket containing soapy water on the lawn, which will bring them to the surface. This is called drench testing.
- Part your leaf blades and examine for small green pellets of excrement.
- Look out for orange/black wasps, which are commonly found where there are grubs. These wasps look for grubs to act as hosts on which they can lay their eggs.
How to treat grub infestation
Once you've ascertained the presence of grubs, the treatment method will depend on the severity of the infestation. On new turfs, spraying is mandatory since grubs can do more harm to new lawns than old ones.
Visit your turf supplier and ask them to recommend an effective insecticide and follow instructions to ensure that all the grubs and eggs are killed. Even if you have no grubs yet, you can ask for a preventive insecticide to spray on to protect your lawn. Late summer to early fall is the best time for treatment since the grubs are still small and easy to kill. Water thoroughly after spraying to carry the chemical everywhere through the lawn. You can skip the watering treatment, however, if rain is expected later that day or the following day.
Respray again after one week to break the lifecycle of the worms by killing the eggs. Fast action is necessary because once the grubs proceed to pupa stage (before they turn to moths) treatment won't have an effect.
Fertilize the damaged lawn areas and water generously to aid recovery in those areas. Water the lawn thoroughly after fertilization so that the nitrogenous fertilizer does not burn the grass, especially during summer.