|By Skip Richter
ome weeds are wimps. Just swat at them with a hoe or cover them with a few leaves and they wither and die in a heartbeat. Others require a little more careful digging or perhaps a squirt of a little herbicide to take them out. Then there’s bermudagrass and nutsedge, the weed world’s dastardly duo.
If you are putting in a new garden, it is far better to eliminate any persistent perennial weeds before you begin to plant, even if it means delaying planting for a while. If you already have a garden in and these two “weeds from Hell” have invaded, your task is more difficult and your options are more limited. These perennial weeds can turn a pleasant gardening experience into a Sisyphean task as they keep coming back again and again, sentencing you to a summer of hand-to-weed combat.
These two weeds may well be responsible for more sweat, tears, profanity and exasperation than all other weeds combined. If you have been battling these unwelcomed invaders to little avail I have good news. They are not immortal or invincible. They can be controlled, but the battle is not for the faint of heart. Armed with a few tips and a proper mind set you can win this battle.
So let’s begin with a little psychological adjusting. Remember in the movie Patton when the general paces back and forth across the stage at the start of the movie telling the new recruits what they are in for and helping them understand the proper perspective they need in order to win? OK that is what I’m up to here.
Get in touch with your inner Terminator. Be ruthless. You can never feel sorry for a suffering weed or take a break from the battle. Never let ’em up for air. Hold ’em under until the bubbles quit coming out! It’s either you or them and by golly it’s gonna be you! That garden belongs to you and you won’t rest until every single weed sprout and seed is dead, muerto, history, kaput, compost.
Two rules of winning the war on weeds are consistent effort and getting an early start. The problem with most attempts at managing these weeds is that we gardeners tend to fight them a while and then let up. Once they have a chance to get some green leaves up in the sunshine for a few weeks they have replenished their reserves and we basically get to start over. Remember, never let ’em up for air.
This turfgrass and pasturegrass has a serious problem with understanding the concept of borders or respecting our opinion of where the lawn stops and the flower bed begins. Bermudagrass spreads by above ground stolons, below ground rhizomes. Common Bermuda and some varieties also produce seeds. It can survive drought and thrives in sun and moist, rich soil conditions.you know, like your garden. Here are some strategies for managing this species.
This option is no fun, but can be effective when the infestation is minor if you start early in the season so as to not allow the weed time to spread very far. You just need to stay at it. When a sprout appears, use a spading fork to lift the soil so you can get as much of the underground rhizomes as possible. Pace yourself and give the task just a little time each morning in the early hours when it is still reasonably cool out.
Rototilling or plowing in the summer exposes the rhizomes to the drying sun and forces the plants to use stored energy to regrow. This must be repeated frequently many times to have a desired effect. The minute it starts to grow, till it again.
Such tillage is hard on the soil, breaking down structure and burning up organic matter, but this can be fixed later with additions of compost. I have seen a field of Bermuda turned into a peach orchard in this way. At the end there were still a few living remnants of Bermuda, but the vast majority was destroyed. If seeds are in the soil they will still be viable and apt to return.
Some gardeners have had limited success with vertical barriers into the soil to keep the rhizomes from moving in underground. A barrier is basically an underground wall to block out the bermudagrass.
The barrier material needs to be impervious to the stolons and able to last for a long time underground. Thick plastic and weed barrier fabrics can work if they extend at least 8 inches or more deep. It helps to angle the top of the “wall” a little toward the garden side to direct stolons growing inward from the outside upward or sideways rather than down under the barrier.
I think barriers are among the least practical options. It is a lot of work to trench completely around a garden and install a barrier. The garden has to be pretty much bermudagrass free to begin with. You will still need to defend the border of the garden as the Bermuda stolons will try to creep in over, and if not deep enough, under the barrier.
I have had fair success holding bermudagrass at bay with a paper mulch. The basic technique is to cut the weeds down close to the soil with a mower or weedeater. Then wet the soil thoroughly and cover the surface with newspaper 6 to 8 sheets thick. Overlap the newspaper as you lay it, making sure the soil surface is completely covered so no light reaches the ground. Wet the newspaper as you lay sections to help it “stick” down. Then cover with a mulch of leaves, pine straw, grass clippings, or compost.
If you see bermudagrass peeking through, it will be because there was a hole or gap in the newspaper. Just pull the top off of the plant and patch the hole with a section of newspaper, wet it and cover with the mulch. You can set transplants through the paper but bermudagrass will find the holes, requiring some hand pulling around the base of the plants.
I have not kept at this technique for an entire year to see if it has long term effects in controlling bermudagrass, but it does reduce it a lot and makes an otherwise infested garden patch bearable for the season. Perhaps a reader has given this technique a more long term try and can offer more light on its success.
This may be the best technique of all for managing bermudagrass. There are many types of landscape fabrics on the market used as groundcovers in nurseries or as weed block in ornamental landscape beds. Experiments at Boggy Creek Farm, an organic produce farm in Austin, have shown these fabrics to effectively eliminate bermudagrass if left on the surface for at least a year.
Purchase a wide section of the fabric and place it over an area where you wish to establish a garden or a section of garden plagued by bermudagrass. Secure the edges with pins provided by the product manufacturer, bent sections of coat hanger or bricks. Don’t put weights or pins anywhere except the edges. You can cover the fabric with some leaves if you don’t like the look of the black groundcover.
Give it an entire year or more. When you remove it, the Bermuda will have died trying to grow in the warm moist conditions without sunlight to produce life sustaining energy. The only Bermuda you will see after removing the cover is perhaps some seed that lands in the area or runners creeping in from outside the covered plot.
You can use the technique to recapture lost ground a section at a time until the garden is yours again!
Glyphosate (Roundup, Green Light Com-Pleet and Kleenup) and several other weed control compounds are quite effective in killing bermudagrass, but such general herbicides will kill other green plants the spray contacts. Glyphosate breaks down quickly so you can replant within 10 days to 2 weeks. There are also ingredients selective for grassy weeds that don’t pose a threat to most other plants. Two examples are sethoxydim (Poast) and fluazifop (GreenLight Bermudagrass Killer, Grass-B-Gone, Ornamec and Fusilade).
Both of these herbicide ingredients are most effective on actively growing bermudagrass. On dormant or drought-stressed bermudagrass they are not very effective. Therefore, you will need to wait until grass resumes vigorous growth for it to be an effective control. Repeat applications are usually needed as there are always a few weeds that escape or seeds that germinate later.
In order to avoid damaging plants while minimizing pesticide applications in the environment, I have devised a weed wiper that is simple to build and very effective. It allows you to control weeds coming up here and there among desirable plants without getting virtually any product on the soil or garden plants.
Purchase one of those “grabber” devices used to reach a jar off of a high shelf. They usually have either suction cups or rubber grips on the end that pinches closed and a squeeze grip handle at the other end. Their length is just right for reaching to the ground while you stand upright. That’s right, no stooping!
Take a small kitchen sponge and cut it in half. Use a small bolt, washer and nut to attach the two sponge pieces to the pinchers. It may be necessary to drill a hole through the pinchers depending on the particular product you buy. Then mix a strong solution of glyphosate, fluazifop or sethoxydim in a squirt bottle and wet the sponge. Use the wet sponge to squeeze and wipe the weeds, taking care not to contact desirable plants. It is easy, puts virtually no pesticide in the environment and it works.
Nutsedge, often called “nutgrass,” is really not a true grass, but instead a member of the sedge family. Its proper name is nutsedge or for you Latin lovers, Cyperus esculentus (yellow nutsedge) and Cyperus rotundus (purple nutsedge). It is closer kin to Papyrus (used to make the ancient writing paper of Egypt) or the ornamental Umbrella sedges, than to true grasses like crabgrass, St. Augustine or bermudagrass.
This African native plant has spread throughout the New World. Because of its ability to thrive and persist, most gardeners and farmers would agree that to know it is to hate it.
Can’t Beat ‘Em? Eat ‘Em!
The species name esculentus means edible and yes you can eat the tubers or nuts of yellow nutsedge which have a slightly sweet, nutty or almond-like flavor. The tubers of purple nutsedge are too bitter. There is even a cultivated variety of yellow nutsedge Cyperus esculentus var. sativus that produces larger tubers. This plant despised by us gardeners is known in various parts of the world as Chufa, Earth-Almond and Tiger Nuts.
Ancient Egyptians loved Chufas. In fact, archaeologists examining the opened tombs of Pharaohs have often found a small quantity of mummified Chufas in “easy reach” of the corpses! Now, I’ve heard of being buried with your family pet, but being buried with your “nutgrass” is taking things a bit too far!
In Spain and some other countries, the drink Horchata is made by mixing the ground tubers with sugar and water, to create a milky liquid.
I once ordered and grew some Chufa Nuts (please don’t tell anybody) in my garden and although they grew, they weren’t very impressive to the palate. They have a distinct almond flavor, but are very “woody” in texture. After a while you give up chewing and remove a bit of sawdust from your mouth!
Our own beloved yellow nutsedge is the same genus and species but a different variety. Its tubers are smaller and scattered out further from the plant – a trait which improves its survivability (and weediness!).
Know Your Enemy
Nutsedge tubers are produced on rhizomes (underground stems) that grow to a depth of about 12 inches. Each tuber has a number of buds on it, a fact which leads to its tenacity. When one sprouts up into a shoot and you chop it off another will grow to replace it, as many as 7 to 10 times! Researchers indicate that the tuber uses about 60 percent of its reserves sending up the first shoot and about 20 percent on the second shoot, but if you quit chopping after even the fourth shoot emerges and give it some time to grow it will replenish the stored energy and you get to start all over again. Remember the General Patton speech?
By early May a tuber allowed to grow unchecked will already be forming side tubers on its rhizomes. Each side tuber forms a plant and soon is sending out its own side tubers. When a nutsedge shoot reaches the surface it forms a basal bulb, from which grow roots and more rhizomes with new tubers at their ends.
The tuber’s skin contains a chemical substance that inhibits sprouting. Soil moisture “washes” this inhibitor off of the tuber allowing it to sprout. This is one reason why the plant thrives in a wet area of the lawn or garden and proliferates during wet spring seasons. Some tubers won’t sprout in a given season. This is why it can appear that you’ve killed every plant by late summer or fall and then find an even greater infestation the next spring.
One tuber under moist sunny conditions can eventually form a patch 10 feet or more in diameter. In one year, under ideal conditions the outward growth from one tuber has the mathematical potential to produce 1,900 new plants and 7,000 new tubers. Now you can see why it’s so tough to control! If there is any good news it’s that they tell us that individual tubers do not last longer than 3 years (thanks a lot, right?).
Depleting Plant Reserves
If you continue to remove the new plants before they have a chance to replenish the reserves you can eventually starve and kill them. In order to do this, remove nutsedge plants before they have 5 or 6 leaves. This means eradication of any visible plants a minimum of twice a month. Up to that stage new side tubers have not yet had time to form.
Chop, Dig and Hand Pick
You can chop the tops off repeatedly and consistently although that is probably the least effective option for managing this weed. Digging out the tubers is better although it is pretty labor intensive as most readers already know.
Spading or rototilling and picking out the tubers that surface is also helpful, but many get buried in the process. Like other digging methods you will have to stay at it faithfully for a season or two if it is to be successful.
Spraying the tubers or using the wiper device described previously is another way to wear the plants out. Herbicide products will not eradicate nutsedge in one or two applications, but, if done correctly and at the right time, will reduce the infestation and force the surviving tubers to use energy reserves to send up new growth.
Products containing glyphosate can be effective as can the natural product pelargonic acid (Scythe and Quik Weed Killer). Pelargonic acid doesn’t translocate down into the weed like glyphosate but rather burns the top back, forcing the plant to use reserves to try and regrow again in an effort to survive. Halosulfuron (Manage) is labeled for use in turf areas and translocates down providing fairly effective initial control. Imazaquin (Image) is also labeled for sedge control in turf but is not as effective as halosulfuron. Repeat applications will be required with all products in order to maintain control.
If you choose to use an herbicide don’t wait until the plants are fully grown. You can kill the tops at that stage but the plant will not move the product down to the tuber to kill it, so your spray will only have a temporary, cosmetic effect. You need to spray the new plants before they have about 5 leaves as they are still storing carbohydrate reserves in the tubers at this early stage. Thus the spray has a better chance of killing the tuber or at least weakening the plant significantly.
No matter which method you use, chopping, digging, or spraying, in order for control to be effective, it must outlast the tuber’s ability to regenerate, or an herbicide product must translocate down and kill the tuber. Also remember that at any time there are going to be some unsprouted tubers which will appear later.
Mulching? You bet!
When a nutsedge shoot emerges, it pushes through the soil with a protective sheath around it much like an awl punching through leather. Once it reaches the light the protective sheath opens up and the leaves fold out to catch the sun.
Before it reaches the light it can punch through almost anything. It laughs at the paper technique mentioned for bermudagrass. It pierces thick black plastic. I’ve even seen it push through a new asphalt parking lot! After it is exposed to light it opens up and can’t punch through anything.
Landscape fabrics sold as groundcovers vary in their ability to block out nutsedge. Woven fabrics are not very effective but the nonwoven spunbonded polypropylene products have performed quite well in university trials. The emerging nutsedge shoots have trouble punching through the tangled mat of fibers in these groundcover fabrics. Dupont Typar 307 and 312 (3 oz. per square yard weight) rated the most effective in a university trial.
These fabrics are usually pinned down to the soil tightly which is fine for nursery and landscape beds where you are dealing with “normal” weeds. Experience at the organic farm mentioned earlier showed that if a standard type of groundcover fabric was held down by soil over the fabric or any weight holding the fabric down firmly the nutsedge could punch through. If on the other hand it was allowed to float on the surface and only attached to the soil at the sides the weed could not punch through the loose cover.
These fabrics allow water to move through. Thus the nutsedge tubers sprout beneath the fabric during the warm days of summer and starve to death trying to reach light (remember we must have no mercy!). Sections of nutsedge-infested soil covered with fabric (not weighted down) for about a year have showed no nutsedge regrowth after several years now since the fabric was removed.
The loose landscape fabric technique is in my opinion the best way to manage nutsedge in a vegetable garden. You just have to be patient and leave some areas fallow for a year while the fabric does its work. I suggest laying a thick layer of leaves on the soil surface and then laying the fabric over the top. The leaves will decompose so when the fabric is removed the soil can be tilled up and planted. Then move to a new area the next year. Experiment with this technique to see how it works for you and if a year proves to be long enough to kill the tubers or if the tilling brings up some deep buried tubers that did not yet sprout. I think you’ll find it to be very effective. Should some nutsedge show its ugly head you know what to do, right?
Never Give Up or Let Up!
Nutsedge, although a tough, formidable foe, is not invincible. With diligent, determined effort it can be controlled quite effectively in the home garden and landscape. This weekend rent some old war movies to get in the right frame of mind. Then go out there and storm the enemy in an ongoing consistent blitzkrieg until you regain your lost land.
I’ll leave you with these words from the immortal coach Knute Rockne, as they are fitting for the task at hand:
“We’re going inside of ’em, were going outside of ’em, – inside of ’em, outside of ’em!, – and when we get them on the run once, we’re going to keep ’em on the run, and we’re not going to pass unless their secondary comes up too close!
“But don’t forget men, when we get ’em on the run, we’re going to go, go, go!, and we aren’t going to stop until we go over that goal line!, and don’t forget men, today is the day we’re going to win!
“They can’t lick us, and that’s how it goes! The first platoon of men go in there and fight! Fight! Fight! Fight! Fight!
“What do you say men!”