Controlling Winter Grass during winter

Author: Stefan Palm   Date Posted: 17 July 2019 

If you've noticed a light green, grassy weed coming up in your lawn over the past month, it's most likely Winter Grass. Left unchecked, this fast growing, aggressive weed can take over your lawn. So how can you get rid of it?

Winter grass or poa annua is a what I would call a very persistent and relentless weed in Australia, particularly Southern Australia. 

The word Poa means it’s from the blue grass family and the word annua means it’s an annual weed. The common name “winter grass” comes from the fact that this weed only comes up in the winter time. When temperatures get cool enough, winter grass seeds germinate then stay alive until the Spring when it gets too warm for it to survive. At this point, winter grass weeds die all by themselves.

You’d think that this would make winter grass a fairly insignificant weed but anyone who has waged war against these little blighters will know that they have a secret weapon to ensure their survival and that weapon is their seed!  Each winter grass weed can produce anywhere from 20 to 100 seeds in it's short life. That may not sound significant but picture this – One winter grass seed germinates in early winter. It grows, produces 50 seeds and then dies in the spring with all of those seeds falling to the ground. The next winter, those 50 seeds germinate and produce 50 seeds of their own. Now you have 2500 weeds. It doesn’t take long for your lawn to become a sea of winter grass during the winter.

It’s not all doom and gloom though – there are 2 ways that you can tackle this weed. One way is by using a post emergence control method whereby you attack it after it has germinated. There is a selective herbicide (among others) called David Grays Winter Grass Killer which selectively targets the winter grass. It contains a chemical called Propyzamide which will selectively control winter grass in couch and buffalo lawns. It does this two ways: 1) by surpressing it's ability to produce seed and 2) by killing the weed but only while it's young, before it seeds.  The other (and in my opinion more successful) way of controlling winter grass is to use a pre-emergence method. This is where you use a chemical to kill the seed before it gets a chance to germinate. Pre-emergent herbicides (such as Pendi Pro and Embargo) work by preventing the winter grass seeds from germinating and in that way, they are best applied in late Summer / early Autumn, before it gets cool enough for the seeds to germinate. By applying these chemicals then, you ensure that the seed cannot germinate which in turn, means no more winter grass.  You'll need to do some research before applying a pre-emergent herbicide as not all chemicals can be used on all lawn types. 

My advice :

For Couch lawns:

  1. Hit winter grass weeds with now with David Grays Winter Grass Killer.
  2. In March, apply either Pendi Pro or Embargo pre-emergent herbicide to stop winter grass weeds germinating next season.

For Kikuyu lawns:

  1. There is no product available for domestic lawns to selectively conrol winter grass in kikuyu during winter so for this season, you might have to put up with them.
  2. In March, apply either Pendi Pro or Embargo pre-emergent herbicide to stop winter grass weeds germinating next season. 

For Buffalo lawns:

  1. Hit winter grass weeds with now with David Grays Winter Grass Killer.
  2. In March, apply Embargo pre-emergent herbicide to stop winter grass weeds germinating next season. Do not apply Pendi Pro to buffalo lawns

 

If you're having trouble, or need some more advice, send an email through to me at stefan@paulmunnsinstantlawn.com.au or call us on 8298 0555

 


Comments (1)

Winter grass

By: on 22 June 2018
Thanks - good reading I used your pre-emergence fertilizer and as a result we have only small patches of winter grass this year - sharing your knowledge is much appreciated Also I have a chemical POCHECK --should this be sprayed now and does it need watering. It was recommended by our grounds manager at our golf club I am unsure if it is a pre emergent or if it kills the weed. Many thanks

Paul Munns Instant Lawn Response
Hey Des. Thanks for the feedback on the Pendi Pro. For even better results or when you have a heavy infestation of Winter Grass, you can apply a second application 6 weeks after the first. I had a look at Poachek - its made by a company called Campbells and has and active ingredient called endothall. Following is some information copied from the product label: "This product (Poachek) is a selective post emergence herbicide formulated specifically for the control of winter grass. If used on turf heavily infested with winter grass it is important that a programme of sprigging and reseeding be carried out after the treatment. This product is not persistent in the soil and reseeding can take place 2 weeks after application. Large areas of dead winter grass may form a thatch that may be conducive to spread of turf diseases and it is important that a preventative disease control program be carried out also. Do not use when temperature exceeds 25°C. Do not use on Red Fescues or Kikuyu." I would recommend that you spray it now (or whenever winter grass weeds are present)

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