Bob Westerfield is a garden writer and extension horticulturist.

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Following Directions
by Bob Westerfield       #Advice   #Health and Safety   #Pests

Be sure to follow labeled directions carefully when applying herbicides. Pre-emergent herbicides are applied before the weeds germinate and need to be watered in well after application.

In a world of litigation and lawsuits it is no surprise that any pesticide being sold for profit must contain legal labeling. While it seems like a simple and common sense thing to do, many people never read the labels, or if they do, they don’t really understand them. Consumers flock to the stores on Saturdays purchasing an arsenal of weed killers, insecticides, and fungicides, many times not fully understanding what they have bought or how to correctly apply it. And unfortunately, sometimes the workers in the chain store garden centers are not much more knowledgeable than the consumers. With a basic understanding of pesticide terminology, you can better select the proper product and apply it safely in your home and landscape.

Perhaps it would be best if we explain a few important terms up front. Any chemical, whether manmade or organic, will have a label that contains both the active ingredient and most often a trade name. The active ingredient is the scientific chemical name of the product. The trade name is usually in larger print on the bag and is more of a selling tool to get your attention. It is important to know that a chemical can have many trade names, but the active ingredient name will always stay the same. A good example is Roundup. Many people know this product – but the active ingredient is actually glyphosphate. However since the patent on the product was lifted, it now has dozens of trade names including Cleanup, Farmworks, Karate and countless others. They all contain glyphosphate.

Another important thing to know when searching for a product the correct concentration. On the label the active ingredient will be stated as a certain percentage of strength. It will then list the rest of the percent as other ingredients. This can include water, oils, powders, or other substances. What you really want to know when you are buying products is how strong is the active ingredient that you are purchasing. A product under one trade name may be substantially cheaper than another but it could be due to the fact the active ingredient is at a much lower percentage.

The main label on a pesticide will list the trade name and then more importantly, the active ingredient, which is the true chemical in the product. Trade names can vary but active ingredient names do not.

It is also important to understand other terminology. When it comes to herbicides (weed killers) they will be labeled as either pre- or post-emergent. Pre-emergent means that they should be applied prior to the weeds you are trying to control have germinated. Post-emergents are applied after the target weeds have germinated and are actively growing. Both pre- and post-emergents will normally have certain requirements that should be listed in the label or directions. For example, many pre-emergents should be applied just prior to a rainstorm or watered in shortly after application. This helps move the product into the soil. Post-emergent treatments may require the addition of a surfactant, which is an oil-based product that helps the chemical stick to the leaves of plants. The directions may also call for the product to be applied during specific temperature ranges and allowed to remain in contact on the foliage several days prior to rain or irrigation. It all boils down to learning to read the complete label and instructions. Many people claim that the products do not work, but in actuality, they did not follow instructions. Another thing to keep in mind is that most herbicides work best when plants are not dry or suffering from drought.

The directions on the container will contain vital information such as how to apply, environmental precautions and first aid treatments.

When it comes to product selection, you will also have to choose a type of formulation. The formulation is basically the way the product looks prior to application. Liquid and emulsible concentrates are normally mixed at a certain ratio with water and then applied as a spray on the targeted area. Powders are also usually put into liquid but must be agitated or stirred frequently to keep them from settling. Granular formulations are normally spread out of a hand spreader or fertilizer-type applicator. Once again pay careful attention to what the directions say in terms of how much product to apply. Usually directions will state how much product to put out per acre or per 100 or 1,000 square feet or other area measurement. Remember that millions of dollars has gone into research on the product you are using and what rates to apply. It seems like many people have the philosophy that if the directions say 1 ounce of product, 2 ounces will work twice as well. This is simply not often true. By increasing the rate over the recommended amount you may simply be wasting product and also risking the danger of injury to your plants. At a higher rate some chemicals can cause burning and do more damage than good.

Beyond the active ingredient, amount and type of formulation the label also contains other vital information. Usually in the largest print down near the active ingredient label you will see some type of hazard word. It will normally say Caution, Warning or Danger. The most dangerous pesticides will usually say Danger-Poison. This indicates that even a small amount could kill animals or humans if ingested. Most homeowner chemicals will not have that label but will carry the warning or caution label. Each of these labels still carry precautionary statements about how to safely handle the product and apply it. It will mention protective items such as rubber gloves, possibly goggles, or even a dust mask. A product with a warning label is more toxic than one that has a caution label. Basically these cautionary words are scientifically assigned based on how much of the product it would take to kill a human. Fortunately, the directions will almost always state medical advice on what to do if the product enters your body either through your skin, eyes, or ingestion. Even products officially labeled as organic must describe their safety hazard with one of these three words. It never hurts to have the poison control center number in your phone or on a board near your phone should you ever need it. The national poison control hotline number is 800-222-1222.

Chemicals should be carefully measured and only applied at labeled suggested rates to avoid wasting product and causing potential harm.

The final things normally covered in the label or directions are things such as environmental hazards and proper disposal procedures. Some pesticides should never be applied near a well and so this is normally stated in the precautions. Other products such as insecticides might be deadly to either fish or even honeybees if applied incorrectly. If there is ever a question about whether to apply the product in a certain location, it is always best to go back and thoroughly read the label first. Most products also have a help line number printed on the container where you can call for free advice or directions on how to safely apply the chemical.

Many folks have chemical phobia and would never consider applying a pesticide to their home or landscape. The truth is that we have many household products right under our sink that are probably more deadly than half of the chemicals used in the landscape. The real key to applying these products safely and successfully is learning how to more intelligently read the label and follow the approved directions.


A version of this article appeared in a November/December 2015 print edition of State-by-State Gardening.
Photography courtesy of Bob Westerfield.


Posted: 10/31/18   RSS | Print


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