Ensure lawn herbicide applications are safe and effective by following the tips below.
A wicking applicator used to apply herbicides directly to weeds.
Photo by Steve Manning, Invasive Plant Control, Bugwood.org
Correctly identify the weeds. Herbicides vary in their control of different weed species. Preemergent herbicides are effective at controlling certain weeds, while regular mowing may efficiently manage other weeds. Choose the most effective control method after correctly identifying the weed.
If this document didn’t answer your questions, please contact HGIC at [email protected] or 1-888-656-9988.
Jackie Jordan, Commercial Horticulture Agent, Fairfield, Kershaw, and Richland County, Clemson Extension, Clemson University
Any gardener can tell you just how annoying and frustrating it is to control weeds. That’s why so many of us turn to herbicides because they are an effective way to get rid of these nuisances. Unfortunately, though, since herbicides are poisonous to plants, they can be very dangerous to humans, animals, and the environment itself. Due to this, it is so important that you know exactly how to apply herbicides safely.
Steps to applying herbicide safely:
Step One: Read the Label Thoroughly
In order to make this whole process as safe as possible, you must read the label of your herbicides fully. Do this before applying them in your garden. That’s because the label will tell you exactly what type of plants the herbicide targets. It will also describe the level of toxicity, the safety information, and what type of clothing you should have for this task. This is where you’ll also get instructions for how to use, store, and dispose of the herbicide.
Step Two: Protect Yourself
In step one, you learned that you must read over the label of your herbicide. On the label, there should be a section which talks about what kind of protective clothing and equipment you should use. Some of these protective equipment includes goggles and gloves. Remember, though, you should never wash the clothing you used when applying the herbicide with your other laundry.
Step Three: Make Sure You Have the Right Materials
In order for the herbicides to be effective, you must have the proper equipment for weed killer application at hand. This could be anything from dusters to granular applicators. Once you’ve picked out the equipment you’re going to use, check that there is no leaking connections or nozzles involved here. To make things easier, there are even ready-to-use herbicides offered on the market.
Step Four: Apply the Herbicide
When you’re applying the herbicide, you should do it in a continuous motion with little to no overlap. It’s recommended that you spray the herbicide on your yard so that you don’t have to walk over the areas where you placed the chemicals down. Mornings and nights are generally the best time to put down the herbicides. However, breezy days are definitely the worst, as that’s when particles tend to drift.
Step Five: Clean Up After Application
When you’re done using the herbicide, make sure to thoroughly wash the spray equipment, including any nozzles or flush hoses used. You should also wash over yourself, the clothing you were wearing, and any protective items. The herbicides should then be locked in a cabinet away from the reach of children or pets.
Follow these tips for a safe and effective tree removal
ThoughtCo / Nusha Ashjaee
- B.S., Forest Resource Management, University of Georgia
Homeowners usually welcome trees on their property. But some trees are invasive species that, over time, can take over a garden. Other trees may overwhelm your home, digging roots into the foundation or limiting access to light.
Whatever the reason, if you’re ready to kill a tree, you’ll need to review your options and make an informed choice about the best method for your situation. If you’re concerned about chemicals or are removing a tree in an area where you grow fruits or vegetables, you might choose to physically remove the tree. If you’re comfortable using chemical herbicide, however, a number of options are available.
Chemical herbicides are effective and relatively low cost. On the other hand, they involve using potentially harmful substances in your own backyard. There are ways to mitigate the risk, but you might prefer to avoid chemicals altogether. In that case, you have two options for tree removal: cutting down or starving the tree.
Cutting Down a Tree
If you’re removing a very large tree or are uncomfortable using a chainsaw, you can hire someone to take down your tree. Many people, however, simply cut down their own trees. Once the tree has been cut to a stump, you’ll need to grind the stump to the ground.
Unfortunately, cutting and grinding might not be enough to kill your tree. In some cases, trees will continue to sprout from the stump. If this happens, you’ll need to systematically look for new sprouts and cut them down whenever they appear. By cutting the sprouts, you deny the roots the energy they need to continue to grow.
If neither grinding the stump nor cutting sprouts is enough to kill your tree, you’ll have to dig down and painstakingly remove the roots from the soil. The notorious buckthorn bush/tree is an example of a species that can be killed only by completely removing the roots.
Starving a Tree
The bark of a tree is a system for transporting soil nutrients and moisture to the branches and leaves. With some trees, fully removing the bark around the circumference of the tree’s trunk will effectively starve it to death. This technique, called “girdling,” often is effective, but it isn’t foolproof. In some cases, trees can bypass or “jump” the girdle.
To get the best results, remove all layers of bark in a circle around the tree, cutting about 1.5 inches deep with a hatchet or ax. The girdle will need to be about 2 inches wide to kill a small tree and up to 8 inches wide for a large tree.
Chemically Killing a Tree
Herbicides can kill trees and, properly applied, be safe for the environment. The most environmentally friendly options involve applying herbicide to a specific area of the tree. In some cases, however, the only viable option is to use herbicidal spray. There are five major types of herbicides, only some of which are rated for home or crop use. Triclopyr amine and triclopyr ester are growth regulator-type herbicides, while glyphosate and imazapyr kill plants by interfering with the synthesis of plant proteins. Aminopyralid is primarily effective on legumes such as kudzu and may not be appropriate for your needs. Here are six ways to chemically kill a tree:
- Cut Surface Treatments: This technique involves creating a pathway through the bark so that herbicide can be introduced into the plant’s vascular tissue. Start by making a series of downward cuts around the circumference of the tree with an ax or hatchet, leaving the frill (cut section of bark) connected to the tree. Immediately apply the selected herbicide into the cuts. Avoid spring applications when sap flowing from the wound will prevent good absorption.
- Injection Treatments: Use specialized tree injection equipment to administer a specific amount of herbicide into the tree when the cut is made. Treatments are effective when injections are made every 2 to 6 inches around the tree. For best results, treat trees 1.5 inches or more in diameter at chest height. Injection is often handled by a tree removal company because it requires an investment in equipment.
- Stump Treatments: After cutting a tree down, you can minimize the possibility of regrowth by immediately treating the freshly cut surface with herbicide to prevent sprouting. On larger trees, treat only the outer 2 to 3 inches, including the cambium layer, of the stump (the internal heartwood of the tree is already dead). For trees 3 inches or less in diameter, treat the entire cut surface.
- Basal Bark Treatments: Apply herbicide to the lower 12 to 18 inches of the tree trunk (on the bark) from early spring to mid-fall. Some species can be treated during winter. Use herbicide spray mixed with oil until the bark is saturated. The low-volatile ester formulations are the only oil-soluble products registered for this use. This method is effective on trees of all sizes.
- Foliage Treatments: Foliar spraying is a common method of applying herbicides to brush up to 15 feet tall. Make applications from early summer to late September, depending on the choice of herbicide. Treatments are least effective during very hot weather and when trees are under severe water stress.
- Soil Treatments: Certain soil treatments applied evenly to the soil surface can move into the root zone of targeted plants after ample rainfall or overhead moisture. Banding (also called lacing or streaking) applies concentrated solution to the soil in a line or band spaced every 2 to 4 feet. You can use this type of application to kill large numbers of trees.
Before starting a tree removal project, learn how to use herbicides safely and legally. Herbicide treatments of roots or soil (or sprayed herbicides) can kill vegetation unintentionally.
31 July 2017
Last update: 31/07/17 17:42
With the recent introduction of soybean and cotton traits resistant to synthetic auxin herbicides, farmers have new, much needed options for managing glyphosate-resistant broadleaf weeds. Researchers writing in the journal Weed Technology say use of the auxins isn’t without risk, though. When the herbicides drift off target, they can cause severe injury to sensitive broadleaf plants, such as cotton, wine grapes and soybeans.
The authors conducted a survey of Missouri pesticide applicators to determine what they knew about the new synthetic auxins and their tendency to drift. More than 2,300 commercial and noncommercial applicators responded. Most all were familiar with physical drift and how to minimize it. They were less familiar with volatility and with temperature inversions, which also can influence off-target movement of auxin herbicides.
Vapor pressure, for example, can influence the volatility of auxins, allowing particles to evaporate from their landing surfaces and move back into the air where they can be moved by wind. Less than half of survey respondents understood the link between vapor pressure and volatility.
In addition, few survey respondents were able to identify all the environmental signs of a temperature inversion, which occurs when the air near the earth’s surface is cooler than the air above it. Many approved auxin herbicide labels say applications should not be made during temperature inversions since small herbicide particles might become suspended in the stagnant air mass at the earth’s surface and move to unintended sites.
“It is clear that further education is needed on the synthetic auxin technologies and how to apply them safely,” says Mandy Danielle Bish, Ph.D., a senior research specialist at the University of Missouri.
This article is freely available for one month, “Survey of Missouri Pesticide Applicator Practices, Knowledge, and Perceptions,” is now available in Weed Technology Vol. 31, Issue 2, 2017.
A brief overview of how herbicides are applied, and how to avoid resistance.
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Selective herbicides control specific weed species, while leaving your crop relatively unharmed. Non-selective herbicides are used to clear waste ground and kill any plant they touch.
Herbicides applied to the soil are usually taken up by the root or shoot of the emerging seedlings and are used for pre-plant or pre-emergence treatment.
Positioning of the herbicide in the correct layer of soil is very important, as many soil-applied herbicides are absorbed through plant shoots while these are still underground.
By contrast, herbicides on the soil surface are subjected to several processes that reduce their availability. For example, the herbicide can vaporise (volatility) or be weakened by exposure to sunlight (photolysis).
Foliar herbicides are applied to portions of the plant above the ground and are absorbed by exposed tissues. These are generally post-emergence herbicides and either move throughout the plant (systemic) or remain at a specific site (contact).
Most herbicides are delivered as water-based sprays using ground equipment. This can range from knapsacks to self-propelled sprayers equipped with long booms and spray nozzles.
Herbicides can also be delivered through irrigation systems (chemigation).
As is well known, weed resistance to herbicides has become a major concern in crop production worldwide. Rotation of herbicides from different chemical groups in successive years should reduce selection for resistance and is a key element in most resistance prevention programmes.
Seed companies Dow, Bayer CropScience, Syngenta and Monsanto are all developing seed varieties that are resistant to herbicides, which will make it easier for farmers to use alternative herbicides.
Sources: Cobb, A and Reade, J. 2011. Herbicides and Plant Physiology. John Wiley & Sons: New Jersey, US. Vats, S. 2015. ‘Herbicides: history, classification and genetic manipulation of plants for herbicide resistance’. Sustainable Agriculture Reviews. 15: 153-92.
Patrick McCullough, Extension Turf Weed Scientist, University of Georgia
This is is a common question many turf managers will be asking before herbicide applications this summer. Responsible pesticide applicators will always read and follow label directions before applying any product. However, there is often confusion regarding the language on labels about this issue. Many herbicide labels will contain a statement such as “Do not apply when temperatures are above 90° F”. These disclaimers are usually included on labels to limit the liability of chemical companies when turf managers apply their products during summer heat. This disclaimer is often unaccompanied by anything else to explain or clarify the effects of temperature on potential herbicide injury on turfgrasses.
Turf managers who carefully follow label instructions will see these disclaimers and may hesitate before applying herbicides. Others will question the exact interpretation of these warnings. Examples of questions often asked include the following.
Is it safe to apply herbicides if:
- temperatures are below 90° in the morning but above 90° in the afternoon?
- temperatures are below 90° this week, but rise above 90° next week?
- temperatures are above 90° now but are forecast to drop to the 80s?
- the temperature is 89.9° and the label says do not apply at 90°or above?
Unfortunately, there are no correct (or incorrect) answers for these questions. Herbicide applicators must evaluate their turf and factors that may increase turf injury. Several factors turf managers should consider when applying herbicides in summer include:
- Turfgrass species
- Turfgrass stress
- Herbicide chemistry
- Weed species and population
- Past performance of herbicides
Turfgrass species is a major factor in determining tolerance to herbicide applications. The overall sensitivity level of a species should be evaluated before herbicide applications and closely monitored when temperatures are high. For example, bermudagrass and tall fescue are both labeled for treatments with sulfentrazone (Dismiss). Tall fescue is naturally more sensitive than bermudagrass to sulfentrazone and rates must be reduced to account for lower tolerance levels. Turfgrasses that are sensitive to herbicides under good growing conditions may be more susceptible to injury during periods of heat stress and other herbicide chemistries should be considered.
As temperatures exceed 90° F, cool-season grasses become stressed and consumption of carbohydrates exceeds production through photosynthesis. Thus, grasses such as tall fescue with good tolerance to herbicides during active growth may be naturally more susceptible to herbicide injury during periods of physiological stress. Warm-season grasses grow more efficiently than cool-season grasses under these temperatures and generally have minimal stress when water is not lacking. Uninhibited growth of warm-season grasses at higher temperatures may be attributed to better tolerance to herbicide applications in summer relative to cool-season grasses. However, herbicide tolerances for specific species are all dependent on the chemistry of the product applied.
Effects of temperature on herbicide activity
Turf managers must also understand potential effects of temperature on herbicide activity. Many herbicide chemistries, such as synthetic auxins, have greater activity at warm temperatures compared to use during cooler weather. For example, Trimec Classic (2,4-D + dicamba + MCPP) applications often have erratic activity in early spring but perform much more effectively in summer. Sensitive species to these herbicides, such as St. Augustinegrass, have a higher risk of injury due to greater activity under excessive heat. Switching to another chemistry, such as a sulfonylurea herbicide, may be a safer option especially at reduced label rates. Enhanced activity of herbicides during these periods may also allow end-users to reduce rates and applications required to achieve desirable weed control.
Targeted weed species and the benefits of control should also be considered before risking turf injury from herbicide use in hot weather. Warm-season weeds that spread laterally, such as spotted spurge or knotweed, will continue to grow during hot temperatures and out-compete turfgrasses for light, water, and nutrients. If continued growth of weeds may result in loss of the overall turf stand, practitioners should consider applying herbicides. Preventing annual weeds from taking over a turf area during summer may help reduce voids in early fall that may allow winter annual weeds to establish. Thus, turf managers must evaluate the risk of turf injury at the expense of weed control and potential implications in long-term management.
Previous turf injury from herbicide applications during moderate temperatures may indicate risk of greater injury during excessive heat. Similarly, past reports of turf safety under high temperatures may suggest a specific product has potential for use under local conditions. It is recommended for turf managers to record air temperatures, soil temperatures, relative humidity, turf health, and other environmental factors that may influence turf tolerance to herbicides. These records can be referenced to plan future spray programs for mid to late summer in subsequent years.
Other environmental factors influence turf injury from herbicides in summer. While temperature is an important factor, high humidity increases absorption of many herbicides compared to low humidity levels. Herbicide applications in early evening when humidity and temperatures decline may help reduce injury potential compared to midday when these levels are higher. However, subsequent heat and humidity may influence turfgrass translocation and metabolism of herbicides that could also limit tolerance levels after applications.
Unfortunately there are no perfect application programs or predictive models to determine safety of herbicides on labeled turfgrass species. It is recommended to spray a test area and evaluate turf injury before making broadcast treatments during periods of excessive heat. Furthermore, if there is uncertainty over making herbicide applications turf managers should wait and assess the benefits of potential weed control. Applicators may wish to consult local extension agents for further information regarding herbicide applications during summer months.
Please share this information with others in the landscape & turf industry. For more information:
Call your local Extension Agent at (800) ASK-UGA1 or locate your local Extension Office
www.georgiaturf.com has a section on identifying weeds under Pest Management and weed control recommendations under the Turfgrass Pest Control Recommendations. (Follow all label recommendations when using any pesticide)
You can also find weed control recommendations in the Pest Management Handbook (Follow all label recommendations when using any pesticide)
Kill the weeds without killing the earth.
- Ohio Wesleyan University
- Brandeis University
- Northeastern University
Treehugger / Caitlin Rogers
It’s been said that weeds are just plants whose virtues have not yet been discovered, but if you’re tired of waiting to find out what those virtues are, you might want to use one of these homemade herbicides instead of the chemical versions.
Many common weeds can be either food, medicine, or unwanted visitors to the garden, depending on the varieties and how you view them. But if you’ve eaten all of the ones you can, and you still need to get rid of weeds in your yard, it’s far better for you, your soil, and your local waterways to choose a more environmentally friendly herbicide than those commonly found in the home and garden center.
Strong chemical herbicides, pesticides, and fungicides can pollute our drinking water, our groundwater, and surface water. You can avoid these long-term negative effects by choosing a gentler herbicide, which won’t contribute to the larger issue of water contamination.
The most environmentally friendly way to get rid of weeds is to pull them up, dig out the roots, let them dry in the sun, and then add them to a compost or mulch pile. However, that method can also take quite a bit of time, so if you’re looking for a quicker way to effectively get rid of weeds, one of these homemade herbicides might be the way to go.
It’s important to note that just because these are “natural” or homemade herbicides, they can still harm your soil, your garden, or your person. An herbicide is defined as a “substance that is toxic to plants,” which means that your garden plants are just as susceptible to these treatments. They could have a negative effect on the soil if applied in large quantities, and they may cause human injuries if misused.
1. Drench With Boiling Water
This homemade herbicide is by far the simplest to prepare, and unless you happen to spill boiling water on yourself, is also the least harmful to both people and the environment.
Simply bring a big pot of water to boil on your stove, then pour it over the leaves and stems of the weeds you wish to get rid of. Using boiling water is an effective method for killing weeds in places such as sidewalk or driveway cracks, or over a larger area that you’d like to replant after the weeds are gone, as it doesn’t leave any residue or have any harmful long-term effects.
As with all of these homemade herbicides, it’s still important to only apply it to the plants you wish to get rid of, as they can easily also kill your flowers or vegetable plants.
2. Apply Heat
The application of direct heat to the foliage of weeds will cause the plants to immediately wilt, and repeated applications will kill any leaves that may resprout from the roots. A flame-weeder tool is available from home and garden stores, which allows you to apply flame and heat directly to the weeds without catching the whole neighborhood on fire.
Dried weeds and grasses can easily catch fire during flame weeding. Do not use this method during dry spells, and check with your local fire department to confirm that the practice is legal in your area.
3. Douse With Salt
Sodium chloride, or common table salt, is an effective herbicide. Because salt can have a detrimental effect on the soil, it’s important to only apply it directly to the leaves of the weeds and not soak the soil, especially in garden beds with other, more desirable, plants.
Here’s how to make a salt spray:
- Dissolve 1 part salt in 8 parts hot water. (It can be made stronger with up to 1 part salt to 3 parts water.)
- Add a small amount of liquid dish soap, which helps the mixture adhere to the leaf surfaces.
- Pour the solution into a spray bottle. To apply, spray the leaves of the weeds, making sure to cover or tie back any nearby plants you don’t want to kill.
Be careful to not soak the soil, and keep this mixture away from cement sidewalks or driveways (it may discolor them). Multiple applications may be necessary.
4. Spray With White Vinegar
Spraying white vinegar on weed leaves will cause the weeds to die off, making room in your yard for more desirable plants. The white vinegar sold in grocery stores is about 5% acetic acid, which is usually strong enough for most weeds, although a more industrial strength version (up to 20% acetic acid) is available in many garden supply stores.
The vinegar can be applied by spraying full-strength onto the leaves of the weeds, being careful to minimize any overspray on garden plants and nearby soil. Repeated applications may be necessary, and the addition of a little liquid dish detergent may improve the effectiveness of this homemade herbicide.
Industrial strength vinegar can be harmful to the eyes and burn skin. Only use vinegar of this concentration while wearing goggles and protective gloves.
5. Combine Salt and Vinegar
Another common homemade herbicide recipe calls for combining table salt or rock salt with white vinegar (1 cup salt to 1 gallon vinegar), then spraying this mixture on the foliage of weed plants. Adding liquid soap is said to help the efficacy of this weedkiller, as is the addition of certain oils, such as citrus or clove oil.
6. Use Borax
Borax, which is sold as a laundry and cleaning product in many grocery stores, can help lend a hand in the yard as an herbicide. Add 10 ounces of powdered borax to 2.5 gallons of water, mix thoroughly, and use a sprayer to coat the leaves of unwanted weeds in your yard. Keep overspray off of any plants you want to keep, avoid saturating the soil with the solution, and avoid contact with bare skin.
Tips for Choosing and Using Organic Herbicides
If you want a chemical-free landscape and also want to defeat lawn weeds, the best defense is weed prevention. But weed prevention can take some time and, on occasion, you may need herbicides.
About Organic Weed Killers
There are more than 30 organic herbicides and other products on the U.S. market that meet organic food production standards. That’s good news, but organic herbicides do have their pros and cons.
One benefit of organic herbicides is that, after they do their work, they dissipate in a matter of hours―not weeks or months. They are not persistent in soil. In general, they do not change soil pH or pollute water through runoff. Many of these products are safer around people, pets, and pollinators than synthetic alternatives.
One downside of organic herbicides is that they often require multiple applications. (That’s sometimes true for conventional weed killers as well.) Multiple applications mean more labor and greater expense.
Impact of Organic Weed Killers on Lawn Grass
Most organic herbicides are non-selective, killing any weed or grass they touch. They work best when leaves are drenched. Multiple sprays are often required, depending on the variety and age of the target plants. For lawns, these non-selective herbicides should be used only where complete removal of all vegetation is the goal.
A few organic herbicides target only broadleaf weeds, leaving grass safe. Selective weed killers include Fiesta, Iron-X, and Bayer Natria Lawn Weed Killer, all based on iron HEDTA. (Some say that iron-based products can harm bentgrass, however.) A.D.I.O.S., a product based on sodium chloride, works on broadleaf weeds but not grass.
Effectiveness of Organic Herbicides
Very few organic herbicides kill roots directly. Perennial weeds with deep roots, therefore, are likely to reemerge. There is one organic product that claims to reach plant roots: A.D.I.O.S. by Herbanatur.
Only specific herbicides, such as AXXE, Monterey Herbicidal Soap, Bayer Natria Weed and Grass Killer, and Finalsan will work on algae, moss, and lichen. In addition, only one product claims to eradicate poison ivy, poison oak, and poison sumac. That is C-Cide, a citric acid product.
Legumes such as crown vetch, black medic, or clover can be difficult to eradicate. Even with synthetic chemicals, they often require a combination of repeat-mowing and multiple herbicide applications. Among organic herbicides, the iron-based products may be the most effective against legumes.
How to Use Organic Herbicides
If you decide to use organic herbicides to manage weeds, it’s important to use them correctly. These tips will help you decide when and how to use your herbicide of choice.
- Organic herbicides reliably kill the top growth of both annual and perennial weeds, so most of these products work best on short, newly emerged plants.
- Organic herbicides are helpful as a second “punch” at weeds that have been “scalped” very low to the soil by a mower or weed whacker. They also work well as a follow-up after “smothering” weeds under paper or cardboard for a few weeks.
- Weather conditions make a difference. Since these products work by contact with leaves, use them on dry days. Those based on acetic acid (vinegar) and fatty acid (soap) work better in warmer weather (over 65 degrees). Examples in this category include Weed Pharm, AllDown, Elimaweed, Green Match, Green Match EX, Scythe, AXXE, Safer Fast Acting Weed and Grass Killer, and Monterey Herbicidal Soap. Some manufacturers suggest that direct sunlight also helps some products do their work.
- It may be easier to kill plant roots during the warmest summer weeks and early fall than in the spring. Plants draw food downward at the end of the growing season, creating greater potential for weed killers to be drawn down into the roots.
Some organic herbicides are exempt from EPA registration. These are also called “25b” products in EPA registration lingo. Examples include Ecosmart Weed & Grass Killer, Burnout II, Weed Zap, C-Cide, Matratec, Matran EC, and Phydura. EPA 25b products can be used without special permission on school grounds and playgrounds, according to a Cornell University report. Other organics, however, are required to have EPA registration, the same as synthetic chemicals. Always look for the “warning,” “caution,” or “danger” messages.
To be safe, bear these tips in mind:
- See the EPA’s list of food-safe herbicide ingredients. Then check the ingredients on the products you are considering.
- Any herbicide should be used when bees and pollinators are least active. Some organic herbicides can be harmful to pollinators such as bees. Read the label.
Organic weed killers may be considered safe for lawn weeds and not safe near food crops. Read the label to learn if a product is safe around the vegetable garden.