Lawn Diseases & Weeds in Australia and How to Treat Them

Lawn Diseases

The failure to correctly identify your lawn’s diseases can worsen the problem.  Here are some of the more common diseases and some tips to look out for to help keep your lawns looking great throughout the cooler months.

brown-patch-lawn-disease

Brown Patch

This is most active and aggressive during its peak growing time. This is when excess water continues to sit on the lawn for long periods of time under humid conditions. These peak fungus-growing conditions are usually brought on by watering lawns at night time.

  • Be sure to only water in the morning, and aim to reduce watering as much as possible until the disease is gone.
  • Aerate the entire lawn to stop further outbreaks. Giving extra attention to the affected areas.
  • Stop fertilising until the lawn is recovered.
  • Apply a fungicide if necessary.
black-spot-lawn-disease

Black Spot

This is characterised by black spots on the upper side of the lawn’s leaves and occurs due to fungal diseases. These black spots not only look unattractive and serve as an eyesore, they sabotage the health of the lawn and weaken its structure.

What you should do to treat this:-

  • Look to avoid over-watering their lawn, particularly in shaded areas
  • Limit watering in shaded areas, it prevents the quick evaporation of dew or surface water and continued dampness will encourage Black Spot.
  • Aim to water in the early morning, deeply but less frequently, to encourage stronger roots and to allow the water to absorb properly and the grass to dry-off.
  • Apply fertiliser, but remember under applying or over applying to nutrient deficient soils can promote Black Spot.
  • Dethatching prevents waterlog in the lawns roots and allows proper drainage.
  • Aeration will improve the lawns ability to absorb water, nutrient and oxygen which will help the lawn stay healthy.
fairy-rings-lawn-disease

Fairy Rings

These are a clear sign of beneficial microbes at work in a lawn, which is all part of the lawn’s ecosystem. For much of the time, these fungal structures remain hidden underground, breaking down organic material in the lawn – which is a very good thing.

What you should do to treat this:-

  • Look to water in the early morning, deeply but less frequently, to encourage stronger roots and to allow the water to absorb properly and the grass to dry-off.
  • Apply fertiliser, but remember under applying or over applying to nutrient deficient soils can be more damaging.
  • Dethatching prevents waterlog in the lawns roots and allows proper drainage.
  • Aeration will improve the lawns ability to absorb water, nutrients and oxygen which will help the lawn stay healthy.
  • Mowing at regular intervals is recommended.

Common Lawn Weeds

Weeds may be green, but they are plants growing where they’re not wanted within a lawn. Unfortunately, weeds are often excellent at surviving and reproducing and are commonly the first plants to colonise and dominate. Here are some examples:-

wintergrass-lawn-weed

Wintergrass

This is characterised by its prolific seed production which makes it hard to manage. It is a pale green colour with smooth leaves and has a white cotton-like root zone.

What you should do to treat this:-

  • There are two methods of controlling Winter Grass –post-emergent and pre-emergent herbicide control.
  • Post-emergent control is when you selectively poison out the Winter Grass weed after it germinates (for example, during the autumn and winter months). The herbicide can take a considerable amount of time to work, anywhere from between two weeks and two months.
  • If the post-emergent is applied too late into the winter, it can be hard to get a result.
  • While Winter Grass is easy to remove my hand, as there is so much of it often it grows back.
  • A pre-emergent herbicide with the Common Active Ingredient of Oxadiazon is recommended.
crabgrass-lawn-weed

Crabgrass

This is one of the worst lawn weeds, and when found, it should be removed as soon as possible. It is identified by its wide leaf blade and grass-like appearance. This weed will send out tough stems with fingers of seed heads at its tips. The seed production is extremely prolific, a single weed can send out thousands of seeds and take over and ruin an entire lawn.

What you should do to treat this:-

  • Regular year-round lawn mowing will aid in constantly removing new weed seeds as they are produced and before they have time to mature.
  • A pre-emergent herbicide with the Common Active Ingredient of Oxadiazon is recommended.
oxalis-lawn-weed

Oxalis

This can appear like a miniature clover plant, but it bears tiny yellow flowers. It spreads through interlocking rhizomes that are easy to break apart, these rhizomes eventually produces tiny bulbils. Anywhere the stem touches the ground the Oxalis weed can root, potentially producing more and more plants.

What you should do to control this:-

  • Hand removal can be done but it is slow and laborious, and it may take several seasons to remove.
  • A pre-emergent herbicide with the Common Active Ingredient of Oxadiazon is recommended.
dandelion-weeds

Dandelion Weeds

These have green leaves edged with teeth that grow mostly flat to the ground and are distinguished by their bright yellow flowers that fade to form a white puffball. They appear in spring and autumn in lawns that aren’t as full and healthy as they could be. Its thick, brittle roots easily split, and any fraction left behind will regenerate.

What you should do to treat this:-

  • With careful digging and pulling the Dandelion weed can be removed by hand.
  • Using post-emergence herbicides (referred to as broadleaf weed control) are the most effective dandelion killers that are safe for lawns. The Common Active Ingredient 2.4-D is an example of a selective and systemic post-emergent herbicide.
bindi-weed

Bindi

This is a broadleaf winter annual. It is a very invasive, low growing weed that produces bur-like fruit that poses a hazard to humans and animals due to their sharp edges. The weed evolves during winter and develops carrot-like leaves, during spring it produces a single flower that matures to form a prickly seed pod with three spines.

What you should do to treat this:-

  • The best time to remove Bindi Weeds is during late winter or spring.
  • If there is a small amount of Bindi in your customer’s lawn, then hand removal is suitable if the plant along with the root are removed.
  • If the lawn is rife with Bindi, a Broadleaf Weed Herbicide with the Common Active Ingredients of Clopyralid, Diflufenican and Potassium Salt is recommended.
About Author : David
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