Lawn Grubs & Fungal Disease

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Lawn Grubs & Fungal Disease

16 September 2018 Weeds, Pests & Diseases

This page will help you to identify various types of pests & diseases and provide some advice on how to easily manage them yourself.

ALWAYS read & follow the manufacturers instructions & safety precautions with any herbicide or pesticide.

Lawn grubs

Lawn grubs are a problem that needs to be dealt with straight away before they cause any significant damage.

  • There are three types lawn grub that eat the leaf of lawns in South East Queensland. These are Army Worm, Sod Web Worm and Cut Worm, these are all larvae of small moths that are particularly active from December to May especially after periods of rain.
  • A healthy lawn will easily recover from a mild outbreak of grubs however newly established lawns left unchecked can be completely destroyed in severe outbreaks especially on Blue Couch varieties.
  • To check for lawn grubs walk the lawn in the early evening and look for the presence of the small white moth, this should cause them to fly away, another indicator is the presence of a small red wasp which flies low over the grass during the day, The wasp is searching the lawn for a host grub to lay its eggs into.
  • Another method to check for the presence of lawn grubs is to lay out a wet hessian sack or a large wet rag over the suspected areas in the evening, check under the sack in the morning and the grubs should still be active in the dark cool environment.

How to treat for lawn grubs

  • For a quick kill, most lawn grub killers are suitable for use on turf, check the label for compatibility with your lawn type, sprays can be toxic so follow the directions on the label carefully, we recommend Amgrow Patrol from Lawn Solutions Australia it has good effectiveness, it's a safe to use granular product, and the 1.5kg pack is usually enough to do multiple applications.
  • Ultraviolet bug zapper lights (or similar) are quite effective, they won’t stop the larvae from dropping in and causing some damage, but they will help catch some of the moths before laying eggs in the area, preventing major out breaks.
  • Avoid heavy applications of high nitrogen chemical fertilisers during the summer months, alternatively use organic fertilisers and seaweed based products that strengthen the turf plant making it less desirable for grubs to eat.
  • Lawn Grubs can strike again too! the chemical only kills active insects, so in another 2-3 weeks if you get new larvae laid into the lawn then the chemical will not affect them and the cycle can start over again, so after applying your chosen pesticide it's best to regularly check for new activity & re-apply if necessary, most products such as the Amgrow Patrol above reccommend re-appliation in 7-10 days.

Fungal Diseases

There are many fungal diseases that affect turf such as ‘brown patch’ & ‘leaf spot’, periods of high humidity and rainfall increases the chance of infection. Use the identification chart below to see if you have any of these.

Tips to help avoid or treat fungal diseases

  • Avoid fertilizing with high nitrogen fertilizers during these events
  • De-tathcing is a good way to prevent fungal diseases, where there is an excess of thatch, the turf tends to produce roots in the organic layer, the condition of which can fluctuate from saturation to drought, once the thatch is wet, it remains damp for long periods, this favours for the growth of fungi.
  • Ensure sure you are following correct ongoing watering techniques, sometimes regular light waterings can actually be harmful and may create a constantly moist & humid environment which funghi can thrive in.

Fungicides can be applied if required, as with all fungicides and poison products ALLWAYS CHECK THE LABEL and follow the manufacturer’s instructions.