Is Kikuyu invading your lawn?

If there is one thing to be said about kikuyu, it would be that it is HIGHLY INVASIVE. For those trying to get rid of it, this can pose a significant problem.

If you have it in your grass and you don’t want it, the question we get asked regularly is, "can I successfully get rid of it?" The answer to that question is yes, and no….

How does kikuyu get into your lawn in the first place?

Kikuyu is more aggressive in nature than any other lawn so its potential to invade your lawn and take over is high. It spreads by both runners and by seed. It's also by far the most common lawn in South Australia meaning there is probably a kikuyu lawn near you ready to get its hooks into your lawn. There isn’t a variety of lawn available in Australia that can successfully compete with it so if you find it showing up in your lawn uninvited, eventually, it can completely take over. The most common ways that it finds its way into your lawn are:

• Seed germinating. Birds can drop it in and it can blow in from around the neighbourhood. 
• Contamination. Lawn mowing contractors can bring in stray runners and seed on their mowers which can fall on your lawn and grow
• Invading runners. Underground runners can invade from your neighbour's lawns or from nearby parks, gardens and nature strips

Why is it so hard to control?

Kikuyu has an underground network of runners called rhizomes which spread out where they can’t be seen. That means that what you can see on the top is the tip of the iceberg. What you see on the surface is only a small percentage of the overall plant. Hand pulling it out is no more successful at getting rid of it than trying to kill a daisy bush by picking the flowers off it. What you leave behind are the rhizomes which send up some more growth to the surface. Even if you dig the area completely out and replace the soil, there will probably still be runners under pathways and in garden beds that surround your lawn area ready to re-invade at the soonest opportunity. Then there is the seed – many kikuyu varieties produce a seed that blows around looking for a place to grow so even if you get rid of the runners, there's nothing to say that dormant seed won't germinate in the soil.

Aside from this, kikuyu has a very neat way of preserving itself when times are tough. If it doesn't get enough water or conditions are not favourable, it will go into what's called a drought-induced dormancy. This means that while it may dry off on the surface and look like it's completely dead, as soon as it rains again it can sprout up and start growing again at full tilt. This is frustrating when you're trying to kill it because just when you think you've got rid of it, it comes back. 

Sounds pretty bleak, doesn’t it! The way I see it is that you have a choice – If you have kikuyu invading your lawn, either let take over learn to manage it (when maintained, kikuyu looks really good and has some great advantages) or take measures to control it. This usually involves chemical sprays, both selective and non-selective.

What are the options to remove kikuyu from your lawn or at least slow it down?

Selective Chemical Control:

If you have kikuyu invading buffalo, fescue or rye, there is virtually nothing you can do to stop it in a selective way. When it comes to couches (ie Santa Ana, Windsor Green, Tiftuf etc),  there are some selective herbicides that you can use to suppress kikuyu. That means you can spray them all over the couch and they will just target the kikuyu not the couch. The reality is that you will probably never get rid of it because it will most likely re-invade from its original source but you can certainly suppress it which means you won't see so much of it on the surface. The most notable chemical for the suppression of Kikuyu in Couch is Monument Liquid by Syngenta.  It's one of the only chemicals registered for this purpose and is a commercial group B herbicide. This means it has some very specific spraying requirements so if you're thinking about using it you’ll need to get a licensed sprayer to apply it for you. It's also worth noting that you can't use it within 20m of waterways and within 60m of any other vegetation (which cuts out its use in home gardens). Other options for suppression of kikuyu in couch include selective herbicides that contain DSMA and MCPA. These are available off the shelf in hardware stores and usually have names like Paspalum killer or Paskill etc. Although not noted on the bottle for the control of kikuyu, they will burn back kikuyu on the surface without harming the couch. They also selectively control weeds like paspalum, crabgrass and some broadleaf weeds. Once again, read the instructions and directions before applying. Because of Kikuyu’s aggressive nature, you will need to repeat applications of these chemicals as required to keep the Kikuyu in check. The best time to spray is during the warmer months when the Kikuyu is active and able to draw in the chemical.

Non Selective Control:

If you have kikuyu invading your buffalo, tall fescue, rye or bluegrass lawn then you can't use the selective herbicides mentioned above because they will harm the rest of your lawn. The only solution here is to spot spray with glyphosate (eg Roundup). Keep in mind though that glyphosate is nonselective meaning it kills all types of lawns. You have to be careful to only apply it to the kikuyu, not the lawn you are trying to preserve. If you do happen to spill or apply some to the lawn around the kikuyu, be aware that glyphosate will travel up to 10cm back into the plant it makes contact with. This means that a small amount on the lawn can result in a dead patch the size of a dinner plate. 

No control at all:

If your lawn is more than 25% kikuyu, then there is a fair chance that it will be so entrenched in your lawn that it will be impossible to remove. You can spend a lot of time and money trying to remove it only to find that you have been largely unsuccessful. In these circumstances, my advice is to learn to live with it. When treated well, kikuyu is an attractive, drought-tolerant, hard-wearing grass. It has excellent colour year-round and is virtually indestructible. If you water, feed and mow it as required you may even come to appreciate it!

I hope this helps – feel free to leave comments on your success stories and tips on controlling kikuyu in your lawn.