Monthly Archives: July 2014

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:

Tree Health: Fighting Fungus

The history of the site is telling; imagine inspecting this tree 10 years in the future and not knowing that the roots were cut early on in the tree’s life.
Photos by John C. Fech, UNL, unless otherwise noted.


Fighting Fungus … a daunting magazine article title and overall endeavor indeed. However, it’s a battle worth waging, regardless of the difficulty factor. Though a bit on the trite side, the phrase attributed to Theodore Roosevelt, “Nothing in the world is worth having or worth doing unless it means effort, pain, difficulty,” is often shortened and modified to “nothing worth having is easy” and certainly applies in this case.

Though it’s sometimes a difficult task, the challenge of keeping trees healthy and fungus-free is best accomplished through a multifaceted approach. Identification, monitoring, evaluation of methodologies, preventative measures and conducive growing conditions are some of the more important considerations.

Regular inspection

Whether you call it monitoring, scouting or inspection, a regular close-up look at trees on a customer’s property is a tried and true part of integrated pest management and integral to fighting fungus. If the goal is to keep fungi at bay, you need to know when and where they are attacking, or at least present. If you don’t look, there is no real way to know.

So, what is “regular?” In terms of tree inspection, regular means frequent and thorough. Since many fungi that cause problems for trees are active in the spring, regular inspection should be more frequent in the spring than in the summer or fall. As a result, symptoms are noticed sooner and there is more time left in the year to treat. When maladies are noted in the fall, the action is more a matter of notation and recommendation for follow-up applications in spring, especially if the treatment threshold has been surpassed.

The often underutilized part of inspection is profit. In short, do it, do it often and make money from it. When one considers the investment of time, training and effort that a qualified tree worker puts into their career, it needs to pay off in one way or another. If certification through the International Society of Arboriculture (ISA) or a state arborists association has been achieved, the knowledge, skill and experience must be factored into the equation. After all, the ISA doesn’t hand out certification to just anyone.

A good way to be sure that inspections are an integral part of the income stream is to explain to customers that inspections are just as important as spray applications. Depending on where your customers live, it may be wise to equate monitoring for insects with a fall furnace checkup or a spring air conditioning service. No one wants to suffer through a cold winter or hot summer without relief. If the temperature outside is the same as it is inside in summer or winter, then the equipment is broken or it’s an anomaly.

In terms of the number of site inspections, it’s dependent on the disease susceptibility of the species on the property and the localized conditions. For example, if a given customer has a ginkgo, a red oak and an Osage orange tree, they would need fewer inspections per season than one with a crabapple, an Austrian pine and a cottonwood; the former are generally considered to be disease-resistant trees, while the latter are more likely to develop fungal problems from time to time. Likewise, since many fungal pathogens require high moisture content on foliage to develop and infect a tree, properties with low air flow across leaves are more likely to be conducive to ongoing problems than ones with good air circulation. These factors should be made clear to a customer when pitching the service of regular inspections.


Determination in the endeavor of fighting fungus on landscape trees is important from two perspectives: determination in the sense of persistence, and determination in the sense of identification.

First, identification. Even after years and years of diagnosing unknown maladies, determining which exact causal agent is responsible for the symptoms that have been produced on a tree can be challenging. How can you fight something if you don’t know what it is?

Determination, or diagnosis, can start in many ways. My preference is to begin with known maladies of the tree species. For example, crabapple has a long history of susceptibility to powdery mildew, apple scab, fire blight and cedar apple rust. If the customer has a crabapple, your first step is to get to know the symptoms of these diseases and compare the current presentation of the leaves, stems and trunk to those established characteristics.

A good second step is to consider the micro and macroclimates of the property. When I was starting out in horticulture and arboriculture, a wise arborist did me the favor of teaching me how to walk the entire property, as well as the adjacent lots and neighboring areas, looking for clues as to what might be influencing the current situation. He taught me to carry a clipboard and use it to make notes on wind patterns, sunlight penetration, coverage of the root system with impervious surfaces, and competition from other species.

Knowing the history of a site is useful as well. Interviewing the owner and possibly the neighbors about recent herbicide applications to the turf, soil modifications, utility work, and the performance of other woody species can be helpful in determining what’s causing the tree’s health to decline.

Leaf scorch on dogwood underscores the need for regular inspection.

It’s not all about fungus. To eliminate possible nonliving/abiotic organisms as causal agents, items important to learn to distinguish between fungus and non-fungus. In fact, one of the little known secrets of determination is that less than half of the causes of tree problems are related to fungal or bacterial organisms. Overwatering, lack of separation of turf and trees, planting errors and mower blight are just some of the non-fungal inputs that can cause trees to suffer.

Next, persistence. Because it’s not easy, sometimes it just takes time to get it right. After a good first look, take the time to check the resources on your bookshelf. Go online and type in phrases such as “maple diseases in the Northwest” or “ash problems” into Google Images or Yahoo Image Search. You’ll be amazed at what you find. Talk to other service technicians in your company and university extension faculty about possible causes.

As you move through the process, stay in communication with the client. They’ll appreciate your thoroughness and your persistence.


Whether you’re delivering a joke at a dinner party or buying an airline ticket, timing is undeniably crucial. The same is true when fighting fungus on broadleaf and evergreen trees. Too early or too late with inspection, determination or treatment is not going to cut it. Correct timing is important for each of these factors. The timing needs to be right for inspection in order to be ahead of the curve, to read and react in relation to the clues given by the plant. The determination of the causal agent needs to be on track, and needs to be done in advance of the treatment application if one is necessary. Treatments applied before or after the vulnerable stage of the fungus or plant part are simply not effective and should be viewed as a disservice to the customer.

Each is important on its own, but the correct timing of all three needs to occur in order to conquer fungus. With time, training and experience, as well as due consideration of the key elements presented in this article – regular inspection, species vulnerability and characteristics, the history of the site, differentiation between abiotic and biotic causes, persistence and timing – the fight can be won.

John C. Fech is an ISA Certified Arborist, PNW ISA Certified Tree Risk Assessor at the University of Nebraska-Lincoln and a frequent contributor.

(Article courtesy of Tree Services Magazine: