Goathead weeds or puncture plants are found in many parts of the world. They can be harmful to livestock, plants, and animals due to the sharp spines in their fruits or burrs. The seeds of goatheads are hard to destroy, making it difficult to remove these plants. Read this Gardenerdy post to know how to get rid of goathead weeds.
Avoid mowing the goatheads to eradicate them, as they will grow flat against the ground.
The goathead plant (Tribulus terrestris) from the family Zygophyllaceae and order Zygophyllales, is a prostate annual herb that is distributed around the world. The plant is found in parts of southern Europe, southern Asia, Africa, and Australia. It can grow in various types of soils. It mostly grows in spring and summer. Germination requires warm temperatures and moisture. After the plant matures, it can tolerate arid soils as well as hot and dry conditions as it develops a deep taproot to pull in water. The plant produces many prostate stems that emerge from the crown to produce a thick mat. The leaves are dark green, opposite, and hairy. The fruits are woody burrs with sharp and projecting spines. The seeds are covered with a hard caltrop-like case. Some other common names for the plant are puncturevine, bindii, caltrop, devil’s thorn, and tackweed.
The plant can cause harm to livestock and people if it comes in contact with their feet. The spines of the fruit can cause injury. If these plants grow in orchards, pastures, among crops, or on the roadside, they may harm the grazing animals by causing injury to their mouth and digestive system due to the spines. Their leaves are also toxic for animals when consumed in large amounts. They can also cause necrosis of the skin, lead to blindness and in extreme cases, they may even cause deaths of young animals.
Ways to Get Rid of Goathead Weeds
▸ To get rid of a goathead weed, pull the entire plant slowly from its taproot before it starts producing seeds. If pulling by hands, wear heavy-duty gloves. Then discard the plants by placing them in a plastic bag and sealing it. After doing this, burrs or seeds might drop on the soil. They can be removed by sweeping the ground or patting it with a carpet to which the burrs will stick. A pumpkin can also be used for this purpose. Roll the pumpkin over the soil and the goatheads will get stuck into its flesh. Then discard the pumpkins. To remove a plant which has already produced seeds, take care to not knock it off while pulling it out. Most importantly, keep a regular watch on the new growth of weeds.
▸ Get rid of goatheads by burning the seed pods and plants. Never allow the weeds to dry out or remain unmonitored. This will lead the seeds to come loose and disperse.
▸ Another way is placing thick organic or synthetic mulch in the soil to control goatheads in orchards, plants, crops, and pastures because they can prevent light from entering the soil. However, this is not a very effective way because if the burrs happen to fall on the mulch, they can start growing due to its deep taproot.
▸ Maintaining aeration of soil and use of competing plants is another effective way of getting rid of goatweeds. Aeration is done by creating perforations in the soil so that more air, water, and nutrients can enter it. This will favor the growth of more plants and limit resources for the weeds. The reason behind planting competitive plants is that the weeds do not compete well and do not survive when near other plants, mostly perennials.
▸ Two types of biocontrol organisms called puncture vine weevils are known for eating goatheads. They are the Microlarinus lareynii, which eats the seeds and Microlarinus lypriformis which eats the stem, branches, and crowns of the weed.
The adult weevil (Microlarinus lareynii) eats a burr or seed and lays an egg in it. The egg hatches and the larva feeds on the seed. It enters deep into the seed and destroys it. Microlarinus lypriformis has the same life cycle. The only difference is that it lays its eggs on the stems, branches, and the crown of the weed. The larvae feed on the stem and make their way deep into the stems or branches. The adults come out of the stems, branches, or crowns. In this way, the stems and branches are destroyed. It is best to use both the weevils at the same time to kill the weeds. However, the weevils do not survive well in winters.
▸ Spraying of post-emergent herbicides like those containing 2,4-D, glyphosate and dicamba are also very effective in controlling the weeds. Prepare a solution by diluting the herbicide and then use it onto the soil or on the goathead plants. However, always follow the instructions given on the label of the herbicide. While doing this, take care that other plants are not injured. Also, the herbicide should not be overused. To prevent the plants from emerging, use a pre-emergent herbicide before germination.
▸ Freezing is also another good way of killing the plant. Puncture vines do not survive in cold conditions. The sustainability of the plants is less during the autumn and winter seasons.
Points to Consider
▸ Keep goatheads away from shoes, car or bicycle tires, and wheels of mowers or carts.
▸ Do not buy puncture vine weevils from biological control suppliers as weevils from another place may not survive in your area.
▸ Avoid composting goathead weeds in the composter as they will germinate.
▸ Before burning the weeds, water the surrounding area thoroughly. Additionally, keep a water hose readily available nearby, in case the fire starts spreading.
▸ Check with your local fire department for regulations prior to burning. Some will require a burn permit.
▸ Avoid burning goatheads in windy conditions.
These ways and tips to get rid of goatheads should help you in saving other plants in your orchard or garden from these weeds and in avoiding the harm they might cause to you or the livestock.