Tree Health: Pesticide Safety

By John C. Fech

Determining the need for pesticide application is a good first step.

(Photo court esy of James Kalisch, UNL.)

There are many critical issues in the tree care industry, from invasive pests to the implementation of pest monitoring, from training new workers to marketing to new customers, and from tree risk assessment to tree establishment. Human nature being what it is, our interests are not equal amongst them. Unfortunately, although it’s of central importance to tree care workers and arborists, pesticide safety is one area where there is a low level of interest. As such, it is easily overlooked, and in some cases downright ignored. There are several facets of pesticide safety, and they should be considered in the daily course of operations.

Safety during selection

When choosing amongst all the available products, consider those that require less exposure during application, mixing and storage. Straightforward discussions with product distributors and university extension faculty as well as a thorough reading of the label will provide information about which products are associated with the various types of protective gear and equipment. When the decision is being made, selecting product x, which requires less exposure, over product y is a type of preemptive action that can prevent potential problems before the product is put in the spray tank.

In addition to exposure, consider the toxicity level of the product. The three signal words are good clues for this factor. Products with the signal word “caution” are lower in toxicity; those with the signal word “warning” are moderately toxic; and those marked “danger” are highly toxic. For example, soaps and oils are generally safer than other pesticides since they are lower in toxicity and as such are marked with the signal word “caution.” The LD50, (lethal dose to kill 50 percent of the test population) is another indicator of potential risk from the product.

Bark treatments can be very effective as targeted applications, but can produce unacceptable drift. (Photo court esy of James Kalisch, UNL.)

Safety during mixing

Your eyes, hands, face and, dare I say, the organs below the belt need to be protected. When in doubt, focus on the protective gear needed when mixing the product with water, as this is when you’re dealing with the product in its most concentrated form and therefore poses the most risk. At a minimum, a face shield, rubber apron, nitrile gloves and rubber boots should be worn.

Typically, eye and skin exposure is the most common when applying or handling (loading, reorganizing, reading labels, etc.) pesticides. It’s also the easiest route of entry to prevent. Chemical-resistant gloves that cover the hand and forearm provide very good protection. Unlined gloves made of nitrile, neoprene or butyl rubber are excellent choices. Fortunately, quality gloves are not expensive. Depending on the frequency of use, manufacturer and product choice, gloves may last from a day to a week to a month.

Safety during application

Whether the application is a spray, injection or basal drench, appropriate footwear is commonly overlooked when applying or handling pesticides. Boots can either prevent or promote pesticide poisoning. Leather boots, such as work boots or cowboy boots, can easily absorb pesticide products. The harm can be initial and long term. If a liquid product is spilled on leather boots, it’s possible for the pesticide to be absorbed as it soaks through the boot. If this occurs, immediately consult the pesticide label for information on how to reduce harm to your body. Better yet, read the label before mixing or applying the pesticide so you know this information beforehand and can act immediately.

Storage facilities should be clean and well organized.

(Photo court esy of Clyde Ogg, UNL)

Chronic or long-term pesticide poisoning can result from small amounts of product that are absorbed with each application. The product is likely to be retained in the leather, creating an unacceptable risk to the applicator. Chemical-resistant boots or shoe coverings should be worn. Use the pesticide label as a guide when choosing footwear. Generally, rubber is considered to be a better material for preventing pesticide absorption than leather.

For eye protection, consider the wide array of goggles on the market. Most are designed to fit over eyeglasses. Some have shielded vents that allow for reduced fogging and heat buildup. All are designed to prevent splash and particle drift during application. The bottom line: eyewear is important. In many application scenarios, the product mist is quite fine and may be unnoticeable to the applicator.

In addition, for specifics on rates, water pH, reentry time, need for surfactants and compatibility with other pest control agents, as well as what personal protective equipment (PPE) may be required, read the pesticide label thoroughly before use. That’s where you’ll find this and other valuable information.

Safety after application

Quick, think of three things that you don’t use your hands to do … kind of hard to think of any, let alone three. Even after applying a pesticide with nitrile rubber gloves, get into the routine of washing your hands. The rule is to do so three times using hot water, followed by a good rinsing. Of course, this is to be done before using the restroom, smoking, eating or any other activity where you might touch an unprotected part of the body or material that might absorb or hold pesticide residue, such as a ball cap or steering wheel.

Proximity to streets and sidewalks is always a concern.

(Photo courtesy of John C. Fech)

Proper laundering of pesticide-contaminated clothing is essential for applicator safety. The first consideration is to deem any clothing worn while at work as contaminated and in need of washing. It’s important to always wash pesticide-contaminated clothing immediately after use (don’t let it lay in a heap for a week or leave it in your hamper, and be sure to separate it from other laundry) and start by prerinsing. Research at several land-grant universities has indicated that using hot water, heavy-duty liquid detergents and the maximum water level for the washing machine are most effective at removing pesticide residues from clothing.

Just as with rinsing spray tanks and backpack sprayers, removing possible residues from the washing machine is important. When the wash cycle is completed, run the empty washer through a complete cycle with detergent and hot water to clean the machine.

Storage of unused pesticides is another facet of pesticide safety. Certain products may require unique conditions, so storage location/facilities may vary, but all should be well lit so it’s easy to read the label and distinguish similarly looking products from each other.

Generally, favorable environments for pesticide storage maintain a temperature of 60 to 65 degrees Fahrenheit, have a low relative humidity, are out of direct sunlight, and are arranged in such a way that access is easy and open and allows for quick observation to see if products are missing, bags are torn or put away incorrectly. A good storage unit will be able to be securely locked and posted as a pesticide storage area, will keep pesticide products dry, is fire resistant, and contains a well-functioning exhaust fan for ventilation. It’s wise to design the facility to make it adaptable and allow room for expansion. To create good storage conditions, follow these rules: the area must be stable, easy to use, and accommodate the products you use.

The author is a horticulturist and certified arborist located in Omaha, Neb.

(Article courtesy of Tree Services Magazine: