Goathead – (also known as puncture vines)
Tribulus Terrestris is a plant in the family Zygophyllaceae. Many people refer to this family of plants as the caltrop family because of the hard sharply pointed seed pods produced by these broadleaf plants.
We have all encountered them, sometimes painfully. Many many years ago, I developed my intense dislike for these low growing spreading plants. They were the cause of hours of work on a repeated basis, repairing the inner tubes of my bicycle tires.
Much older now, I am still at war with this insidious plant. I seem to battle it constantly in portions of my lawn. From an organic standpoint, it is one of the hardest of weeds to control.
Controlling Small Goathead Infestations
If your lawn is plagued by goatheads in small patches, the most effective method I have found is to remove them by hand. After years of dealing with them, I have found a method that I think works well. It doesn’t involve chemicals, spraying, or applying any pre-emergent.
The only tool you need is a knife with a relatively narrow, sharp blade. I also suggest you wear a pair of leather gloves and have a container at hand, such as a plastic 5-gallon bucket. This method does involve bending over or getting on your knees. That is the only drawback I can find.
How to remove the Plant
Locate the center of the goathead. If it is a young plant, this will be easy. The younger the plant, the easier it is to remove. Very young plants can usually be removed by grabbing the plant on the stem as close to the ground as possible and pulling upward with a slight twist. If you are lucky, the entire taproot will come free. At the worst, the taproot will break off below the ground surface. Breaking the taproot below ground insures a sure kill.
If the goathead plant is larger and has started to flower, take care. It has probably already produced some seed pods that are lurking hidden under the leaves ready to do their damage. Use the tip of the knife to gently move the spreading stems of the plant to locate the central stem Insert the knife blade just beside the stem where it enters the ground with the flat side of the knife facing the plant. Push the knife a few inches into the soil and then give the knife a twist, moving the sharp edge toward the stem of the plant. When the edge of the blade is against the stem, give the knife another twist and cut the taproot below ground and then flip the plant gently up and over.
Practice Practice Practice
It takes a little practice, but once you master the movement, you can eradicate a patch of goatheads in a few minutes. Use the knife blade to lift the severed plant and put it into the bucket. Don’t try to compost these plants. The seeds can lay dormant for years, and most home compost piles don’t get hot enough to get 100% kill rates. Put them in a plastic bag and toss them in the trash. This is one plant that deserves to go into the landfill.
Unfortunately, I can’t guarantee that this is a 100% effective way to rid your lawn of goatheads for all time. I will say that it will greatly reduce the number over time. Anyone walking by or over your lawn with a goathead seed pod stuck on a sock or shoelace can deposit a seed that will germinate.
Large Scale Goathead Infestations
I see many places where goatheads have gotten a foothold over large open areas. Most of the time, this is due to the gardening or farming practices that are being employed. Goatheads thrive on bare tilled ground. They will invade and establish themselves anywhere they find bare ground, even the hardest and most compact soil will offer them a place to germinate.
Tilling – A Big Problem
The practice of tilling to control weeds can cause the problem to worsen. Since the seed pods can lay dormant for years tilling the soil can return old seeds close enough to the surface to germinate. The most effective eradication scheme can be undone after apparent success by tilling and bringing these older seeds to the surface.
Goathead Removal – Our Preferred Method
In our opinion, the best method of control over large areas is a well planned organic approach that uses mechanical eradication, building soil health, maintaining appropriate cover crops over all the bare ground or mulching to prevent the plants from finding a place to establish themselves. Even then, if your neighbors or adjoining property continue to host goatheads, you will have a continual maintenance problem.
The most effective way I have found to deal with large patches of goatheads without resorting to highly toxic and dangerous chemical agents is to burn them. I use a propane weed burner. This is the first step in the process. The weed burner produces an intensely hot flame that will destroy the plant parts above the ground while doing relatively little damage to the subsoil. The heat will also destroy any detached seed pods. I prefer to work in small areas, burning the goatheads, making sure I get enough contact to kill any unseen seed pods. You should then immediately remove the plants using a square-edged shovel. Put the burned weeds into a bucket or other container to minimize spreading the seeds that may still be viable and disposing of the dead plants.
Cautions and Care
There are some cautions to using a weed burner. First, check with your local fire department or fire marshalls office and make sure it is legal to use a weed burner in your area. There may be restrictions on its use. Second, don’t do this alone. You need at least a second set of eyes and hands. Your helper should be watching for stray hot spots that may develop. You certainly don’t want to start a wildfire. Have a water hose close at hand at all times and be vigilant. Third, know your equipment and how to operate it safely. Read the directions, Wear the appropriate safety equipment, including gloves, eye protection, and clothing.
|Desert Mallow (Sphaeralcea ambigua) a perennial shrub that can help in controlling goatheads. Grows well in desert regions.|
Once an area is clear, there are a couple of possibilities. If it is fall and past the time when seeds will germinate, I will sheet mulch the area. For really large areas, this may not be feasible. The better alternative may be to seed the area with cover crops. This can range from a mixture of native grasses to native perennials or other cover crops that do well in your growing zone.
Do’s and Don’ts
Under no circumstances should you disturb the soil surface after you have removed the goatheads. Your main goal should be to get some cover on that bare soil. Sheet mulching is good because it prevents any seeds or plants still alive from getting light. Planting cover crops will eventually help by competition and providing some live mulch on the soil. The key here is to get the soil covered in some way. The long-range goal is to build the soil, encourage the soil biome to grow, and to keep live roots in the soil all the time, year-round.
Large Area After Care
Once you have your area relatively clear of goatheads, the important thing to do a routine followup to keep control. Allowing the goatheads to flower and go to seed is a sure way to give up any ground you have gained in the war.
A 10% horticultural vinegar solution is effective at controlling the younger weeds. For more information about using vinegar as a weed killer, see our article here.
Spot spraying the young goatheads with the vinegar solution will kill them easily. Just remember that the vinegar will also burn off the green vegetation of any other plant that it contacts. Take care where you spray.
If the goatheads have not yet begun to flower, they can be dealt with by hoeing or pulling. However, this method has to be used before the plants begin to flower and go to seed, producing the thorny seed pods.
The goal on large area eradication and maintenance of a goathead free environment (and most other weeds for that matter) is the health of the soil biome, the establishment of cover crops and ongoing maintenance. Healthy soil will support a healthy cover crop. Whether it is native grasses, native perennials or production crops, the presence of living roots in the soil and the thick cover of growing plants above ground will impede the goatheads’ chances of germinating. Ongoing regular maintenance will quickly and easily eradicate those young plants that do manage to find a place to start.
The war will continue. Hopefully, the battles will be less frequent and less intense. Good luck.
For more information about organic gardening and lawn maintenance, visit our website at West Texas Organic Gardening.
For specific help with weed control or turf maintenance, check out these articles.
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