Controlling Autumn weeds in lawn

Author: Stefan Palm   Date Posted: 26 April 2018 

Autumn, leading into winter is a prime time for weeds to begin emerging in your lawn. With the extra moisture around and with less competition from summer active lawns (as they go into winter dormancy), weeds find the conditions irresistible.

 As the weather cools down, weed seeds and bulbs stored in the soil from previous seasons germinate and grow, reminding you once again how persistent they can be!

I've certainly noticed in the last week there has been a surge in the germination of weeds around my garden and I'm fairly certain this rapid germination will continue for the next few weeks as conditions remain warm. My advice would be to wait for another week or two before you start spraying weeds so that you get as many as possible in the one go. 

The most common winter weeds are winter grass, sour sobs and of course, the common broad leaf weeds like thistle, dandelion, creeping oxalis, clover and bindi eye. Have a look at our handy Weed Identification Chart to see which type of weeds you have!

There are some things that encourage excessive weeds like very low mowing, insufficient fertiliser and inadequate watering which can weaken the stand resulting in any bare spaces quickly being colonised by weeds. Ineffective control measures in previous years can also lead to weed numbers increasing. They do this by flowering and dropping their seeds in the soil, ready to germinate when the conditions are right.

Most weeds in a lawn containing couch, buffalo or kikuyu grass are easily controlled by spraying with a selective herbicide. The type of herbicide you use will depend on the weed you are targeting.

Broadleaf Weeds:

For broad leaf weeds, use a product containing MCPA and Bromoxynil such as Amgrow Bin-Die. This sort of chemical is selective which means it is especially designed to be sprayed all over the lawn. It will target the weeds and will not affect the grass you are spraying. Generally speaking, broadleaf herbicides take around 10-14 days to kill the weeds. 

Wintergrass:

Wintergrass is just starting to emerge now as the weather begins to cool down. Wintergrass can be controlled by using a herbicide containing propyzamide such as David Grays Winter Grass Killer. Follow the instructions carefully and make sure you spray evenly over the whole lawn area. Wintergrass killer is also a selective herbicide and is safe to use on couch and buffalo lawns (in WA).  As this chemical is soil activated, it is important that the sprayed area is watered within 24 hours of spraying. If you have wintergrass growing in kikuyu, then you can't use a propyzamide based chemical as a control measure. Your only option here is to wait till February and apply a pre-emergent herbicide such as pendi pro which will kill the seeds of the wintergrass weed before they have a chance to germinate next Autumn. Click here for more info on pre-emergent control of wintergrass. 

To some degree, weeds will always be an uninvited guest in your lawn at different times of the year but with some vigilance, you can get on top of them. For more advice on controlling or identifying weeds, give us a call on 8298 0555. 


Comments (1)

Winter grass killer on buffalo grass in SA

By: on 12 March 2018
<p>Noticed David Grays winter grass killer is suitable for buffalo but only in WA. Can I use it in Adelaide on buffalo grass?</p>

Paul Munns Instant Lawn Response
I see you've carefully read the label! It is exactly as you say and I have it on authority that the reason for this is due to Adelaides typically heavy clay soils compared to WA's sandy soils. This has an effect on how the chemical reacts in the soil which can effect how it reacts with the turf variety. Buffalo is sensitive to chemicals so this is the reason for this advice on the label. I would always follow the label.

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