Alternatives to Roundup

Roundup is a popular glyphosate-containing herbicide used in home gardens and agricultural settings. Research on Roundup and cancer has found that cancer risk increased by 41% with high long-term exposure to glyphosate. Currently, the warning label on Roundup products does not indicate this risk, but the U.S. Environmental Protection Agency is re-evaluating whether glyphosate is an environmental contaminant and, as part of this review, will re-evaluate its cancer risk.

Further research has linked glyphosate to non-Hodgkin lymphoma and oxidative stress in the body, which can be a precursor to cancer and other diseases. Additionally, a 2023 study shows that glyphosate may increase estrogenic activity in breast tissue cancer cells, causing abnormal cell growth.

The links between Roundup and cancer leave many people looking for alternatives to the herbicide. Natural Roundup alternatives use soaps, oil or acid to kill weeds, but some other options use salt, vinegar or boiling water. These safe alternatives to Roundup can be effective if used properly.

Natural Roundup alternatives don’t contain glyphosate. Most available products contain plant-based oils or soaps. They may also have acetic acid, or vinegar, that damages the leaf cuticle and causes cell leakage to rapidly kill weeds. Various soap, vinegar and salt combinations are readily available, safe and natural Roundup alternatives. These products also kill weeds and other plants on contact, so you should only apply them directly to weeds.

Manual weed control methods, such as mulching, are very effective at controlling young weeds. Pouring boiling water over adult plants also deters growth. Other natural Roundup alternatives like corn gluten meal and iron-based herbicides have mixed efficacy.

Acid-Based Herbicides

Many safe Roundup alternatives use vinegar to kill weeds. Vinegar is 4%-6% acetic acid, although more concentrated formulas are available. Acetic acid damages the outer layer of a leaf, causing leakage within leaf cells, which damages the weed.

However, acetic acid-based products are not always able to access the roots of a plant and may kill only part of the weed that’s above ground, allowing plants to recover from treatment. As a result, you may need to apply acetic acid-based products multiple times to the same plant to slow plant growth.

Acetic acid concentration is important when choosing an acid-based herbicide, and so is the age of the plant. Scientists from the USDA Agricultural Research Service found that 5%-10% concentrations of acetic acid killed weeds in the first two weeks of life. However, older plants needed higher concentrations. Researchers also found that higher acetic acid concentrations killed all life stages of plants faster.

Acetic acid can be unsafe to use without proper equipment. It can damage the skin and mucous membranes in the eyes, nose and lungs. Always follow any safety directions on an acid-based herbicide, and use protective goggles and gloves.

Corn Gluten

Corn gluten is a natural alternative to Roundup that can kill germinating seeds or seeds that have just begun to sprout. It won’t kill plants that are already growing. Corn gluten granules, powder or liquid products can be spread over large areas of the garden or crop to kill germinating seeds. Corn gluten doesn’t work well with extensive rain or watering and is expensive compared to other natural Roundup alternatives.

Corn gluten also has other limitations. Research conducted by Oregon State University found that corn meal didn’t control germinating seeds or any other growth. Additionally, corn gluten increased grass and weed growth because of its high nitrogen content, which is a potent fertilizer.

Studies inside greenhouse labs have shown that corn gluten kills germinating seeds effectively, but in-field results have not been promising. Multiple studies have failed to show that corn gluten is an effective herbicide in actual use, even against germinating seeds, partly because the substance requires dry conditions.

Corn gluten is safe for humans but may pose environmental risks. The nitrogen in corn gluten finds its way into groundwater and can cause excessive nitrate levels and algae growth in water systems. The University of Maryland issued a warning about corn gluten herbicide use, stating that the amount of corn gluten needed to suppress germinating seeds contains more nitrogen than allowed by the Maryland Fertilizer Use Act.

Essential Oils

Essential oils contain several compounds, many of which have herbicidal effects on plants above ground. Some can also halt seed germination. Essential oils can damage the growing tissue of the plant by causing cell death, reducing how much energy a plant gets from the sun, altering plant enzyme and hormone regulation and changing how plant cells interact with each other. They may work differently on different plants.

Essential oils can be highly effective herbicides because they inhibit plant growth in many ways. This variety in herbicidal activity means plants have trouble adjusting to essential oil-based herbicides and can’t develop resistance as quickly. Essential oils also pose minimal environmental risks because they’re volatile and dissipate rapidly into the atmosphere. As a result, they’re less likely to leave residue in water or soil.

Essential oil-based herbicides can effectively kill weeds but aren’t without risk. They are not likely to be carcinogenic, but topical application of essential oils can make the skin burn more easily in the sun, potentially increasing the risk of skin cancer. Some rodent studies have also shown that certain components of essential oils can be broken down into carcinogens as the body processes them.

Many of the components in essential oils cause skin irritation, and inhalation can irritate mucous membranes. Breathing in large doses of specific essential oils – like camphor – can lead to coma. Essential oil ingestion can cause nausea, vomiting and diarrhea.

Iron-Based Herbicides

Iron-based herbicides contain chelated iron attached to an agent that’s more easily absorbed by the plant. Broadleaf weeds, in particular, can quickly absorb enough chelated iron to dry up almost immediately and die within a couple of hours of application. Iron also acts as a fertilizer, but not when applied topically.

The application rate of iron-based herbicides determines how effective they will be on different plants because some weeds require more frequent applications than others. Iron-based herbicides shouldn’t be used right before a heavy rain because the iron can be washed off the plant before damaging it. Grass discoloration may occur after use, especially during hot weather. Therefore, some formulations specify not to use on newly seeded lawns.

New delivery systems for plant treatments, called “metal-organic frameworks,” use iron. Iron MOFs are effective at carrying fungicide treatments into the tissues of a plant where they work better.

Iron-based herbicides can cause eye or skin irritation. Prolonged skin contact can cause an allergic reaction in some people or worsen preexisting skin irritation. Iron-based herbicides can also cause lung irritation if inhaled.

Mulch and Manual Approaches

You can kill weeds by suffocation using mulch, certain types of heavy plant growth or weed barrier fabric. Some kinds of groundcover plants grow quickly and stay low to the ground to help block new weeds from emerging. Mulch is any natural material spread along the ground. Leaves, pine needles, dried grass clippings or small pieces of wood are all types of mulch.

Mulch blocks weed seeds and young plants from necessary sunlight. You may use landscape fabric to cover the ground before applying mulch. However, this approach can damage the structure of the soil underneath. Over time, the fabric can break down, leaching chemicals into the surrounding ground.

You can also pull weeds up by the roots for effective but time-consuming weed control. Weed roots can grow deep into the soil and are hard to remove completely. Many weeds continue to grow even if just a small piece of root is left behind. Fire can also destroy weed growth on top of the soil but cannot kill the roots underground. Additionally, fire can be dangerous and hard to control.

Soap Salts

“Soap salts” is the common name for the potassium salts of fatty acids. They’re the main effective ingredient in many herbicides. People have used soap salt products for decades. The U.S. Food and Drug Administration generally recognizes them as safe for food crops.

Soap salts are not toxic to humans or animals if consumed in small amounts. However, skin irritation can occur with contact, especially prolonged contact. Ingesting large amounts can cause stomach upset, vomiting or diarrhea.

Soap salts can pose an environmental risk if they reach a water source because they are highly toxic to many aquatic species. The U.S. Environmental Protection Agency recommends against disposing of these products in water or allowing them to enter a water system. Soap salts break down readily in soil, so they do not usually reach waterways when applied to plants.

Chemical alternatives to Roundup can pose safety risks. A 2020 study of chemical herbicides without glyphosate found carcinogenic chemicals and undeclared toxic ingredients, like heavy metals, in all 14 tested samples. Researchers found carcinogenic polycyclic aromatic hydrocarbons in many of the samples tested, along with the known-carcinogen benzo(A)pyrene. Results also showed contamination with heavy metals, such as mercury. In addition, researchers found arsenic in seven out of 14 samples.

Roundup is a popular herbicide because it’s very effective and kills the entire weed, including the root. However, chemical alternatives to Roundup come with limitations. Some products aren’t as effective during hot weather, and many only kill small broadleaf weeds but not large plants. As with Roundup, these herbicides should not come into contact with surrounding plants because they aren’t selective and can cause cosmetic damage or kill nearby plants.

Although a few chemical alternatives are as effective as Roundup, these products are not better for weed control because many contain chemicals that pose health risks to humans and animals. They can also cause environmental contamination. Manual weed control methods like mulching or using cover crops can block emerging weeds without chemical burdens. Nonchemical sprays are effective at killing weeds above ground.

Integrated weed management is an excellent Roundup alternative because it combines different practices to manage weeds rather than relying on one product or method. In addition, integrated weed management reduces the environmental burden of chemical herbicides and poses less of a risk to human health. Weeds can adapt to herbicides after repeated use, so using more than one tactic keeps weeds from adapting.

There are three areas of focus within integrated weed management. Meeting these criteria improves efficacy. First, limit the introduction and spread of weeds. Then, help plants compete with weeds by “choking out” growing weeds. Finally, make it harder for weeds to adapt.

Integrated weed management can prevent large-scale weed problems. Controlling weeds around the edges of gardens or beds, removing weeds before they grow too large and using only clean seed mixes helps keep weeds in check. Planting seeds shallowly and planting extra seeds allows them to grow into plants quicker, making it harder for weeds to compete. Plants block sunlight and use up available resources like groundwater and soil nutrients. Weeds can adapt to the active ingredients in chemical herbicides, so rotating herbicides with different active ingredients each year makes it hard for weeds to survive.

Roundup continues to be a popular herbicide. Bayer, the maker of Roundup, continues to see big profits from sales. Part of the reason may be because Roundup product labels do not contain warnings that glyphosate is a danger to human health. Multiple peer-reviewed studies on glyphosate show that it increases the risk of certain cancers and other serious illnesses. However, the EPA has not updated its warning labels on Roundup to include this information. The agency is currently reviewing its stance on glyphosate as a human health concern and environmental contaminant.

In 2015 and 2019, California courts found that Roundup caused cancer in multiple cases. Since then, Bayer has been hit with more than 100,000 Roundup lawsuits from farmers, landscapers and gardeners who used the herbicide and became sick. Despite successful court cases against Bayer, consumers remain confused about the negative health impacts of Roundup and sales will likely remain high until the EPA adjusts label warnings on the product.

Roundup works well to kill weeds and is economical in large quantities, further fueling its popularity, especially for large crops. But other less-toxic methods are also effective at removing weeds, particularly the combination of different weed management protocols.