Some say the definition of a weed is a plant growing where you do not want it. Getting rid of those unwanted plants can be a problem. If it isn’t something we can pull or cut out, we often have to use herbicides. An herbicide is any chemical that will kill plants. This may sounds simple, but like any other chemical, to be the most successful you need to apply the right herbicide to the right plant at the right timing. With a little investigation and preparation, herbicides can be a great tool to help you succeed.
As with all chemicals, it is essential that you follow directions carefully. Ideally, we would rather not use chemicals if cultural methods can control the problem, but when necessary, they can be used safely for you and the environment. If you have tried weeding, cultivating and mulching and still have weeds that bother you, it may be time to use herbicides.
Are there lots of types of herbicides?
To start with, all herbicides are either pre-emergent or post-emergent. They are also selective or non-selective, contact or translocated and residual or non-residual. Pre-emergent herbicides work by interrupting seed germination, which keeps new weeds from developing. Pre-emergents are usually used early in the season when seeds are germinating. Post-emergent herbicides work on plants that already have leaves. Using a pre-emergent herbicide to keep dandelion seeds from germinating works, but you would need a post-emergent to kill the existing plants. Post-emergent is most effective when applied to actively growing plants.
There are selective herbicides that will only work on certain plants, and there are non-selective herbicides that will affect any plant on which it is used. Usually a selective herbicide will either target types of plants, such as grasses (monocots) or broadleaved weeds (dicots). Some herbicides work only on the parts of the plant to which you apply it. Others are absorbed and the chemicals translocate (move) to other parts of the plant (such as roots), affecting those parts too.
Why are some herbicides residual and others are not?
This will vary according to the specific chemical, soil moisture, soil structure, exposure to light, temperature and several other factors. Keep in mind that some herbicides will stay active in the soil for years and others cannot be detected a few weeks later. 2,4-D (Weed-B-Gone™) is one of the most recognized herbicides. Used properly, it will kill almost all broadleaves without affecting most varieties of grass. Used improperly, it can affect your grass and neighboring plants, including your perennials, shrubs and trees. To be effective, 2,4-D products need to stay on the treated area for a day or two before it rains or is watered. While using these herbicides, you and your pets should stay away from the area. If you follow directions carefully, it can be a very useful product, but remember to follow instructions. Just because a little is good, a lot is not better, whether it’s 2,4-D or any other chemical.
What is the best way to apply an herbicide?
Herbicides are available both as liquids and granules. Granules are usually quicker and easier to apply. Liquids can be more accurately controlled, but can also be affected by wind and spray drift. Drop spreaders are more accurate than broadcast spreaders. What are the differences between hose-end and compression sprayers? Hose-end sprayers are inexpensive. Some chemicals even come in their own hose-end spray bottles. Hose-end sprayers are quick, but can only be used where your hose reaches, and are not always accurate. Sometimes hose-end sprayers use more chemicals to cover the same area. Compression (pump-up) sprayers are much more accurate and use less chemicals, but are heavy and require maintenance.
Why do I need a separate sprayer for herbicides?
Almost all sprayers have plastic parts that will absorb herbicides and when used later with insecticides or fungicides, may cause damage to your plants.
Are herbicides dangerous to people and animals?
There are dangers while using chemicals that affect pets as well as people. If you use them according to directions at recommended rates, you can use them safely.
Are they dangerous to the environment?
Some herbicides are very residual, affecting plant growth for years. Others break down quickly and cannot even be detected. Read your labels carefully, they always list any environmental hazards.
Should I routinely use herbicides on my yard to prevent weed problems?
As with all lawn and garden chemicals, herbicides should only be used if a problem exists, and only on the areas that need treatment. Routine applications without a specific need can be costly and ineffective.
My biggest weed problem is crabgrass. Is there an herbicide to handle this? Crabgrass is an annual plant. That means the plant that is in the yard will die this winter, but it will leave thousands of seeds for next season. When you find crabgrass growing in your yard, keep it mowed fairly low to minimize the development of seed heads. Use an herbicide to kill it during the growing season if is threatening to choke out your desirable grasses. Next spring use a pre-emergent herbicide to keep the seeds from germinating and forming new plants.
Can herbicides applied to the grass damage my trees and shrubs?
Some herbicides can damage young trees and shrubs, especially those that contain Dicamba. Always look on the label for precautions.
What is the best herbicide to get rid of tough tree saplings and seedlings?
Roundupä, Vine-X™ or similar products work best on the really tough problems, but use it carefully and be sure to follow directions.
Is there an herbicide I can use to keep the weeds out of my flowerbeds?
Preen is a great pre-emergent herbicide for use in flowerbeds. Make sure you check the lists of safe plants before you use it. Like all pre-emergents, it will only keep new weeds out and will not affect weeds that already have leaves or are coming back from a perennial root system.
When in doubt about how to use an herbicide, don’t hesitate to ask an expert at McShane’s Nursery and Landscape Supply. They are always more than happy to help and can give you some really helpful tips!