Controlling Winter Grass during winter

Author: Stefan Palm   Date Posted: 4 May 2017 

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, they 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 buggers will know that they have a secret weapon to ensure their survival and that weapon is seed! Winter grass can produce anywhere from 20 to a hundred seeds in its 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 before your back lawn becomes 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 when its already growing. There is a selective herbicide called David Grays Winter Grass Killer which you can spray it all over your lawn and it will only target the winter grass. It contains a chemical called Propyzamide which will selectively control winter grass in couch and buffalo lawns. It does this by surpressing its ability to produce seed so while it won’t kill the existing weeds, it takes away their ability to reproduce meaning it won’t come back again the next year. You’d need to apply it regularly during the winter to ensure you catch all the winter grass weeds as they germinate. The other (and in my opinion more successful) way of blind siding them is to use a pre-emergence method. This is where you use a chemical to knock out the seed before it gets a chance to germinate. Pre-emergent herbicides (such as Pendi Pro and Embargo) only deal with seed and will not have any effect on living plants so the time to do this is the summer time when there are no winter grass weeds present. By applying these chemicals then, you ensure that the seed dies meaning no winter grass the next winter. (when researching these chemicals, make sure buy the right one for your lawn. Not all chemicals can be used on all lawn types)

My advice…. Hit them with Winter grass killer now and back that up with some Pendi Pro or Embargo in the summer to make sure they don’t come back.


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