Wild mustard control can be a challenge because this is a tough weed that tends to grow and create dense patches that out-compete other plants. Wild mustard is a pain, but it is a bigger problem for farmers than for home gardeners. You can use both physical and chemical strategies to manage or eliminate wild mustard in your yard or garden.
Because it’s so tough, getting rid of wild mustard can be a real project. If you do not want to use chemicals in your garden, the only way to eliminate this weed is to pull it out. The best time to pull mustard weeds is when they are young. This is because they will be easier to pull out, roots and all, but also because removing them before they produce seeds will help limit future growth.
About Wild Mustard Weeds
Herbicides can also be effective in controlling wild mustard. There are several different types of herbicides that will work against wild mustard, but there are some that the weeds have grown resistant to and that will no longer work.
Unfortunately, there are no other cultural or biological control methods for wild mustard. Burning does not help, nor does allowing animals to forage. The seeds of wild mustard can actually be toxic to livestock.
If you have too many to pull, you can mow down wild mustard before seed production, during the bud to bloom stages. This will limit seed production.
Sheron C., Albuquerque
Mustard weeds are very prolific and competitive weeds which invade multiple cropping systems, from lawn and landscape to agronomic crops, throughout the southwestern US. In New Mexico, these weeds are primarily comprised of London rocket (Sisymbrium irio), flixweed or tansy mustard (Descurainia Sophia), or shepherd’s purse (Capsella bursa-pastoris). Mustards, like most plants designated as weeds, have the ability to germinate quickly and mature earlier in the year than our desirable/native plants, which gives them a definite competitive edge. Additionally, London rocket is notorious for overwintering the curly top virus, which can then be transferred to nearby garden crops (i.e. tomatoes, chile) in the spring. This occurs as the beet leafhopper feeds on the mustard plant, carries the virus in its mouthparts which are then used to feed on the garden crops, thus effectively spreading the disease.
If you have mature mustard plants and it is late in the season (such as now) the plant may be too mature to respond completely to an herbicide application, synthetic or organic. In the southern portion of the state (Las Cruces, Deming, Hobbs, et.) temperatures have been so mild this winter that mustard plants are already beginning to produce seed heads with viable seed…at this point the most effective method of control is to cut the roots, rake, or hand-pull and remove the plants prior to dropping their seed. In some of the more northern cities (Albuquerque, Santa Fe, etc.) temperatures may still be cold enough to delay the production of seed heads in mustard plants. If this is the case, as the temperatures start to get a little warmer you can apply a postemergence herbicide, such as glyphosate, as the plant is actively growing and developing a seedhead.
Mustard weeds have annual lifecycles, although they can germinate and grow as both winter and summer annuals depending on temperatures. Additionally, mustards like flixweed and shepherd’s purse have the ability to survive as weak biennials depending on temperatures and moisture availability. Plants with annual and biennial lifecycles must germinate from seed during each growth season. Thus, the key to controlling these plants is to target them when they are newly germinated before they have the ability to produce copious amounts of viable seed and disperse them into the soil to germinate later (in some cases decades later). Mulching (2-4 inches thick) or laying plastic over areas of bare soil will help to block sunlight and prevent germination of mustard seeds. I often get questions asking if allowing plastic covering to be exposed to the sunlight will heat the soil surface to a temperature that will kill dormant weed seeds. While this practice, known as solarization, may help some (which is better than none), generally the soil will not get hot enough at enough of a depth to really make a dent in the seed population. Using a weed burner or a propane flame torch may be effective on germinating plants, but again the soil acts as a great buffer against heat and will not damage seeds unless they are right on the surface. In addition, great caution should always be taken with using flame to control weeds. If you are not opposed to herbicides, a preemergence barrier with the active ingredient pendimethalin will also help to control the weed as they germinate.
If you are not opposed to herbicide applications for weeds that have germinated, you want to try and time these applications when the plant is young (the younger the better) and actively growing. Applications with products with active ingredients like 2, 4-D, dicamba, triclopyr, and glyphosate have been reported to control mustard weeds. If organic options like acids or oils are preferred, make sure that the product that you use is labeled as a herbicide, such as enhanced vinegars. Home-use distilled vinegar is not labeled for use as an herbicide. Since these products only burn and damage the surface of the plant, it is also essential to try and make this application when the plant is young and most susceptible.
The first year, the plants form a rosette of leaves. An easy way to tell if a rosette is garlic mustard is to smell the leaves. They will smell like garlic.
It is a biennial plant meaning it completes its life cycle in two years. The first year, it grows a rosette of leaves. The rosette appears in mid-summer when the seeds germinate. In areas with warm winters, the rosettes remain green throughout the winter, photosynthesizing the sunlight while other plants are either dormant or have no foliage. This gives it a head start in the spring of the second year of growth.
The second year, the rosettes grow into a plant that can be up to 3 feet tall. In late spring, May through June, the plants bloom. The flowers are white with 4 petals arranged in the shape of a cross. The flowers develop seed pods. Each pod contains about 16 seeds. Each garlic mustard plant produces, on average, 600 seeds. When the pods are ripe, they forcibly eject the seeds several feet away from the originating plant. The seeds can stay viable in the soil for up to five years.
Where Did Garlic Mustard Come From?
Ugh, it’s garlic mustard season. The roadsides, the woodland edges, seemingly everywhere I look, garlic mustard is blooming. What is it? Where did it come from? Most importantly, how do you get rid of it?
Garlic mustard is native to Europe, Western Asia and Northern Africa where it is found in hedgerows and along the roadsides and forest edges. It has long been used as food and medicinally as a diuretic. In it native areas, it is kept in check by 76 different kinds of insects including butterflies and moths which lay their eggs on it. The resulting caterpillars feast on the leaves.
Garlic mustard (Alliaria petiolata) is also known as Poor Man’s Mustard, Hedge Garlic, Garlic Root and Jack-by-the-Hedge. It is an invasive plant found throughout the Northeastern and Midwestern US as well as Southeastern Canada. It is called garlic mustard because the leaves have a garlic smell when they are crushed.
A stand of garlic mustard that has choked out other plants on the forest floor.