Control Of Winter Grass

Understanding the annual cycle of winter grass. How to control winter grass and prevent it from encroaching into your lawn...

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How to Control Winter Grass (Poa annua)

Poa annua annua is commonly know as Winter Grass in South Africa. Although Poa is an extrememly diverse genus, there are two broad classifications : the weakly perennial biotype and the annual biotype. The latter true winter annual is by far the more predominant particularly in the Western Cape and the focus of this article is therefore on this particular biotype.

The Winter Grass Cycle

Winter Grass produces seed in abundance on muliple seed heads and it is this seed which provides the predominant germination in the lead up to Winter i.e. during Autumn when temperatures begin to cool. The Winter Grass then grows healthily in the colder Winter months, particularly in shady areas or where it is damp - amongst lawn grass, in flower beds or wherever it can find a suitable space. As the Winter Grass matures it produces masses of seed, and as temperatures rise in Spring and Summer the Winter Grass goes brown and dies off, leaving behind its seed to continue the annual cycle.

Recommended Control

Most experts agree that Winter Grass is best controlled by applying a pre-emergent herbicide known as KERB. Generally KERB should be applied by spraying, starting in early Autumn and during the Winter months when the chances of catching the seed in its pre-emergent germination phase are greatest. For best results it is recommended that application be done when the soil is cool and damp. KERB should only be applied on established lawns. Some Australian experts recommend that lawns be irrigated to the equivalent of 12mm of rainfall soon after spraying and again within 24 hours, presumably to limit or prevent damage to the lawn grass itself. If the infestation of Winter Grass is substantial, then the spraying can be repeated two or three times, at intervals of about two months to the end of Winter. Products for post-emergent spraying might be available but will probably not be necessary.

Other Considerations.

Since Winter Grass produces so much seed, it is easily spread by wind, water, in compost and lawn dressing, under shoes and on hosepipes. It has a shallow root system and when allowed to grow a bit, can easy be pulled out by hand. This method must in any case be used when Winter Grass is found in not-yet-established lawns, or amongst other plants which might be damaged by KERB residue spray.


Questions and comments


The questions/comments section has been closed as of 1 Sept 2015

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Jan 04 2015, 06:02 PM
Hi. We have a rather big lawn (Sasolburg) with mostly LM or Buffalo grass. I have a problem with an invader grass, but I'm not sure what kind it is. It has very thin stems and V-shaped seeds. Can it be Kikuyu? Can I use Lawntyl?
Jan 05 2015, 08:23 PM
If you do a Google search using the keywords "kweek seed pictures" you will see what I am pretty sure you describe as V-shaped seeds. I believe (based on your description) that you have what is commonly called Kweek or Quick Grass (Cynodon dactylon). It is as invasive as Kikuyu Grass and as difficult to eradicate. But it is often used to surface cricket and hockey fields. If well fed and watered it does provide a good hard-wearing and firm lawn. It is naturally blueish green in colour. It often coexists with other lawn grasses such as Kikuyu Grass or Buffalo Grass. There is no herbicide of which I am aware which targets Kweek alone. Hence removing Kweek usually involves spraying with a herbicide which kills EVERYTHING (lawn grass and weeds) and/or working over the whole lawn area with a large fork to a depth of up to 60cms, removing all roots/runners during that process. And then repeating the removal after a few weeks if more Kweek surfaces. Lawnty is not appropriate to use as a herbicide as it states on the package insert that it can be used on Kikuyu/Buffalo Grass without damaging these lawn grasses. So it will not target those specific lawn grasses. Nothing seems to be said about LM Berea Grass. See the link below for more information on Lawnty, in case you don't already have details. Sorry I can't be the bearer of more encouraging news...
Dec 16 2014, 07:18 AM
Hi. What is the best approach to use to remove dodder. I continually remove by hand and have also removed what seems to be its favourite host plants (nasturtiums, daisy bushes, salvia etc.) I have searched for a herbicide to use but am not finding anything on the shelves that has this listed.

Dec 16 2014, 03:05 PM
I must admit I'd NEVER heard of "dodder" before. I do not know in which country you live, but certainly I've never seen it around Pretoria or Cape Town. Dodder is in the genus Cuscuta which has over 145 species. It's apparently very difficult to eradicate and usually takes several attempts, plus a variety of methods. I did find a Dodder Management article on the Internet and am providing it to you below. Hopefully you will find something there to assist you. If I were you I'd try to speak to someone at the Kirstenbosch Botanical Gardens, and see if they know how best to control it. Or you can contact Efekto and ask them if they have a herbicide which specifically targets Dodder. Both of the above institutions would have websites with contact information (provided you do live in South Africa!).
Dec 17 2014, 08:14 AM
Hi Rod

Thanks for your response. I am in Midrand (Jhb). Will chat with Efekto. As I understand it using a pre-emergence herbicide is the best approach.

Thanks once again
Nov 12 2014, 08:11 AM
With what do we fertilize our patch of wonderlawn which has got very sparse? Is this Also the weeds are now taking over because of this. Is their a weed killer we can use, that won't kill the lawn. (Durbanville , Cape Town.)
Nov 17 2014, 09:52 AM
Your Wonderlawn (Dichondra repens) has almost certainly been invaded by weeds because poor soil conditions have not allowed it to develop a thick mat. This is the most common reason for occurrence of weeds - poor soil and resultant unhealthy lawn condition. Firstly, broad leaf weed herbicides are not recommended for Wonderlawn as they would kill your Wonderlawn as well as the weeds. Secondly, a well fed and watered lawn will develop a thick mat which will inhibit weed growth, so that is your best plan of action. I'd recommend : (1) Weed as best you can by hand for now (2) Give your Wonderlawn a good dressing of high nitrogen fertiliser (usually in January, April, July and October but do it now anyway). I'd suggest a pelletised poultry manure such as Neutrog BladeRunner of SeaMungus if you can stand the odor for a couple of days, or good quality finely sieved mineralised compost such as Reliance Soil and More (3) Re-seed or replant the very bare patches with Wonderlawn (4) Water twice weekly in the mornings, deeply, roughly equivalent to 25mm rainfall each time - to encourage deep roots and to prevent diseases which result from evening moisture on the leaf blades. Below is a link with some information about Wonderlawn care etc.
Nov 07 2014, 10:30 AM
how do i dilute Efekto Banweed for treatment of weeds in my Kikuyu lawn. I am in Bryanston
Nov 10 2014, 02:14 PM
You should always follow the dilution instructions on the herbicide package insert exactly as specified. This will minimise the impact of the herbicide on your Kikuyu Grass. There is a recommended pre-spraying procedure which you should adhere to. You can go to the eGardens Library section and find the "Your Lawn Weeds Removal Guide" article. Then scroll down and read through the Responses I've given to some people regarding what to do in preparation for spraying for weeds. I tried to access Efekto's website on your behalf but was unable to gain access to their information on dilution of Banweed MCPA. You can try to look there too once their website is back up and running.
Oct 15 2014, 11:53 AM
I seem to have Poa Triviatis which is a perennial and large patches of this light green grass is growing on my Buffalo lawn. I live in Bergvliet, Cape Town.
Oct 15 2014, 04:22 PM
Thank you for this interesting Question. This is the first time I have heard of Poa trivialis (Roughstalk Bluegrass) - although I may have come across it and know it by sight, not by name. The other Poa variety, very common around Cape Town is of course Poa annua (Wintergrass). I'm providing a link below which is simply a source of a little more information on Poa trivialis. It seems that there is no reputable herbicide which specifically targets Poa trivialis alone. I did see evidence of a herbicide called Certainty, produced by Monsanto, but I would from an ethical viewpoint not ever promote their products. An alternative to herbicide is to hand-weed those areas of Poa trivialis, which I think does not produce as much seed as Poa annua. Otherwise, one can use a product such as Roundup and spray ONLY those areas - but this will kill EVERYTHING on which the Roundup settles (so spray on a windless day when there is no chance of spray drift). I recently heard from someone that Roundup is the same (or similar) highly damaging and dangerous herbicide used during the Vietnam War for deforestation - Agent Orange. So I'm reluctant to promote that either. A landscaping colleague of mine recently told me he had the recipe for a safe home-brewed herbicide which also kills everything on contact - but has non-toxic ingredients. I will get the recipe from him by the weekend and then update this Response. Would it be possible for me to come and see your Roughstalk Bluegrass? I live in Wynberg and could pop over at a mutually agreed time most days. If ok, please let me know your address and/or phone number via email. Thanks
Oct 16 2014, 02:24 PM
Thank you for responding to my Poa Triviatis question. I sincerely hope its not a question of mistaken identity, however, it certainly seems to fit the descriptions and images available on the internet. My lawn was mowed yesterday thus at the moment it's difficult to see the alien grass amongst the buffalo. This will change within the next few days as the alien grass is a brighter green and grows faster than the buffalo and then tends to stick out. You are most welcome to come and have a look and if next Monday (20th) late afternoon - say 17.30 would suit, then I will provide my address in Bergvliet.
Please let me know.
Oct 16 2014, 03:58 PM
I will let you know via email (if you supplied it) if Monday is ok. And here is my landscaping friend's earth friendly herbicide for weeds :

25 litres spirit vinegar (must be spirit)
500 ml orange essential oil
250 ml dish washing liquid

You can make up a smaller batch provided you keep the same ratio of ingredients. You can use more orange oil if you want faster action. The spray will kill any plants on which it lands, so spray on a windless day and concentrate the beam at the Poa only, very gently. There is no residual action after a few hours, he says. But when spraying the Poa, if you accidentally spray onto your Buffalo Grass, it will kill that, so be careful.
Oct 17 2014, 08:16 AM
Thanks Rod. My address is 20 Longueville Way, Bergvliet.
Are you sure about 25 litres of vinegar - should that not be 2.5 litres?
Oct 17 2014, 08:27 AM
Yes, I'm pretty sure about the 25 litres. My landscaper friend had some with him to make up the cocktail a Saturday ago, and it was in one of those 5 litre bottles one sees for fruit juice. Remember that the cocktail is not diluted with water, so one needs sufficient volume of liquid, and the spirit vinegar serves this purpose too. But I have to speak with him today, so will verify the quantity just in case. And thanks supplying your address. I'll be in touch.
Oct 20 2014, 09:00 AM
If it's still ok, I will pop around to your house at about 17h30 today Monday 20 Oct. Let me know if that's still convenient for you.
Oct 20 2014, 09:10 AM
Thank you Rod, 17h30 today would be perfect.
Oct 21 2014, 01:01 PM
Thanks for an interesting on-site visit! You have one of the best looking Buffalo lawns I've yet seen! So your problem grass is not one of the Poa varieties, but more probably one of the Sedge grasses (not Poa trivialis in my opinion). It looks a lot like a large version of Nut Grass, but one would need to see the flower head before reaching a conclusion. There is a Sedge-looking plant that is becoming an increasing problem in lawns in the Western Cape - something called Kyllinga. Please see the first link below for a little more detail. Again, there are different varieties of Kyllinga. The most commonly used herbicide for this type of weed is Efekto's Basagran (see the second link below), but it seems that it works only on White Kyllinga. The website for the first link below does say that Kyllinga can be controlled by a herbicide but they are not more specific. That's all I've been able to come up with thus far.
Oct 21 2014, 02:17 PM
Thanks Rod, I appreciate the fact that you were able to visit. I take it that Basagran will, if used correctly, not kill the buffalo, however, I appreciate that it may not be the answer.
I guess its worth a try, in a small area, to see if it works.
I'm very grateful for your interest and your assistance.
Kind regards
Oct 06 2014, 11:25 AM
Please advise what is the best lawn grass to plant in semi shade conditions in Newlands, Cape Town?
Oct 07 2014, 12:13 PM
Buffalo Grass is usually recommended for semi-shade in Cape Town. It is a water-wise choice and takes traffic. The other shade tolerant lawn grass is LM Berea. Even when a lawn grass is said to grow in shade, it requires SOME sunlight. I saw shade percentages on a website recently, and I think Buffalo would grow in 60% shade, LM Berea in 80% shade. Buffalo Grass is a slower grower than LM Berea. For this reason some people choose to inter-plant the two. Normal Buffalo Grass is blue/green in colour with fairly broad leaves. LM Berea has finer, green blades. A new variety of Buffalo Grass is now coming onto the market - Buffalo Sapphire. It has more fine and greener blades than normal Buffalo Grass, so would mix better with LM Berea. I heard that it was being grown by Shadowlands Nursery. You could call them on 021-9030050 and find out which local retail nurseries they supply, if you want to try using this new variety.
Aug 25 2014, 02:14 PM
How do I rid my Kikuyu lawn of Wonderlawn. I live in Sandton
Aug 27 2014, 03:07 PM
I presume you have positively identified the Wonderlawn, which is classed as a "broadleaf weed". I recommend that you go to the eGardens Library section, then scroll down to the Lawn Weeds article. Once you click on that article you will find some Responses I have given to clients in regard to ridding their lawns of Wonderlawn. In particular, look at my Responses to Dougie and Shirli. Herbicides that can be applied include Basagran, Banweed MCPA and Kombat Weeds. But please ensure that you adhere to the requirements of spraying lawns for weeds - these are clearly stated in the article and in various Responses e.g. water and feed the lawn well prior to spraying, don't mow the lawn before spraying, spray during dry weather, make sure the herbicide stays on the leaf blades for at least 6 hours, repeat spraying process a second time etc. etc.
Aug 18 2014, 04:36 PM
Jenni Moon
When we planted our garden some 10 years ago I decided no lawn, to keep it low maintenance and my husband and I are both retired. The area was cleared by our developer and top soil laid. We had much difficulty digging the heavy clay, however, but had success with some trees and shrubs. The area in between these i planted a groundcover, but could not eradicate the kweek growing through so pulled it all out. we now have a "kweek" lawn we never wanted. Even in the pathways which we lined with plastic and hard landscaping stone which you would think would stop this kweek invasion by blocking the light. Our property is on a slope so we do get rainwater presumably from our neighbours behind. Either the kweek existed before, or was introduced by the copious compost we added to lighten the clay and improve drainage. Our local garden centre said the only way to remove this was to get in a garden crash cleanup guy, remove all the plants and dig the kweek up, then replant. This seems really drastic and we have fully grown Cocos Palms and Strelizia Nicolai and other trees. what do you think?

Aug 19 2014, 10:28 AM
Oh dear! Yes, Kweek is pretty invasive, much like Kikuyu Grass. It will dive quite deep into the soil while spreading. Kikuyu can dive to depths of 1m or more! You may have left some runners deep down when you first cleared the area, which could explain its reappearance. Any compost you put down would just encourage its growth, as would water from adjacent properties. I'm pretty sure any attempt at removal of the Kweek would involve forking the area with a LARGE garden fork, at least to the depth of the prongs of the fork (say 25cm). Thoroughly! My feeling is that it should not be necessary to remove bigger shrubs and trees or palms. After clearing, any reappearance should be tackled immediately. Where you simply can't get to the roots of the Kweek by digging e.g. among tree roots, then perhaps a judicious application of a herbicide such as Roundup VIA A PAINTBRUSH ONLY ON THE KWEEK ITSELF might keep it at bay. A mission but probably a last resort! And regarding the plastic as a barrier : it would not keep out Kweek (same goes for Kikuyu) which will simply find a way through or around it. The plastic would only be protection against weeds. I'll try to get a second opinion on this Question from a friend who is a landscaper, and then post an update here if relevant.
Opinion from my friend not encouraging for you - sorry! Says he undertook a similar task to landscape a garden (requiring complete removal of a Kweek lawn) for a client and the Kweek still pops up from time to time, after 6 years. Situation is better though. In summary, he used a sod cutter and then dug down to 60 cms, removing all roots. Then did a second sweep a few weeks later. Client's garden service continued removal process for a year or so. He does not believe in using pesticides such as Roundup. You did not mention where you live. If in the Cape Town metropol, can put you in touch with my landscaping friend.
Aug 19 2014, 05:05 PM
Thanks Rod. Not the answer I wanted to hear but does confirm what I suspected.
Mar 06 2014, 09:13 AM
Myrray Osborne
Good morning. I'm the new greenkeeper at Bulawayo Country Club Zimbabwe. With winter fast approaching we arer looking at spraying our greens for winter grass. We haven't preyed for several years, we have been trying to dig it out but can't keep on top if it. Can you please tell when I should start spreying and how much Kerb I need to use and where I can get some Kerb.
Mar 14 2014, 09:26 AM
Sorry to take so long to respond to your question! I've personally never bothered to spray with KERB - I simply pull out the Winter Grass by hand in the summer. But mine is a small lawn while your situation is MUCH larger in scale. I recommend that you carefully read information on KERB usage on the following website :
The manufacturers Efekto recommend KERB be used in Autumn and Winter. The dilution is different depending on whether you are spraying for pre-emergence in Autumn (20gms/100m2/5l water) or early post-emergence (40gms/100m2/5l water). You should probably start spraying soon as the Autumn Equinox is on 21 March. You most likely have large areas to spray so it might be worth your while to contact Efekto via their website or helpline and see if KERB is available in industrial quantities. Otherwise it is normally purchased at retail nurseries or co-ops. I have no idea if it is generally available in ZImbabwe, or if you also have co-ops there. I hope this information is of some use to you.
Mar 14 2014, 01:23 PM
Murray Osborne
Thanks for all your help. We spay as well as removing it by hand. We have a small amount of staff so we to do what we can. We have used it in the past but haven't for the last 8 years and now it is out of hand taking over 75% of out greens. As i said I'm new to the job and learning as I go along. Take care will be in touch again. Regards Murray
Sep 28 2013, 10:19 AM
How do I deal with winter grass that has taken over my lawn? Natal Midlands
Sep 28 2013, 01:27 PM
Please go back to the Control Of Winter Grass article, which describes the cycle of Poa annua and gives details on how to get rid of it. Also, take a look at my reply to Des Stephenson, attached to the same article. In essence, irrespective of what lawn grass you have, the approach is the same. Spray with KERB in Spring and again in Autumn and pull out as much of the Winter Grass as you can by hand. Replant any bare patches with plugs or runners of your lawn grass. And be patient - it is not possible to rid your lawn of Winter Grass in one year - you will only be able to minimise the problem or get rid of it completely over a period of several years! Wish I could be the bearer of a more quick and easy solution...
Sep 01 2013, 01:58 PM
Des Stephenson
Is there a recommended treatment for Winter grass in an established Kweek lawn at this time of year? In patches the winter grass appears to be nearly 100%.
I am in Port Elizabeth close to the sea +/- 0,5km
Sep 03 2013, 10:33 AM
Some of the following is a repetition of information given in the original article - please ignore if you so wish! Winter Grass (poa annua) is very difficult to get rid of completely. It produces copious amounts of seed in Spring which then germinates in Autumn. Some of the seed can remain dormant for several years. The most common way of treating Winter Grass invading Kweek (cynodon dactylon) is by using a pre-emergent herbicide – to catch the seed before it germinates by spraying in late Autumn and then again after the seed has been dispersed in early Spring. The trick is to use a spray that does not damage the Kweek in the process. Ideally this is done when the Kweek is at its most dormant stage, theoretically from late Autumn to early Spring. KERB is a poa annua specific herbicide. Apparently the herbicide LAWN TIL, in addition to controlling poa annua will also control other common lawn weeds. Neither should damage the Kweek, but I STRONGLY RECOMMEND that you discuss the products with your local nurseryman, and read the usage instructions very carefully. See if there are any other herbicides for poa annua on the market. This Winter seems to have provided ideal conditions for Winter Grass in the Western Cape, and it is still growing prolifically everywhere. But you can start the process now, and with patience win the battle over a period of time. Just be patient! I hope the above works for you.


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