Choosing is something we do almost every hour of every day. We choose what kind of coffee to have (or not have), which radio station to listen to, what make and model of truck to buy, where to send our kids to school, what form of advertising to use, and which TV shows to watch. Each of these choices has varying levels of complexity associated with them, some simple and others quite complicated. As arborists and tree care workers, most of the decisions made on the job are pretty important. One of these is which pest control products to use.

Just like choosing which make and model of truck to buy, choosing pest control products is a multifaceted process. Many factors are involved, including product application training, cost, necessary equipment, availability, need for adjuvants, odor and possible conflicts with other products in a tank mix. Wading through the selection process isn’t easy, and decisions should be made only after a careful analysis of all available information.

Identify the causal agent

The first consideration is to accurately identify the pest that is causing damage. A product selection process that is based on incorrect identification of the causal agent will always result in control failure. Products that control pests x and y should not be applied to control pest z. Overlooking correct identification is akin to taking the wrong prescription medicine for your illness or going to the foot doctor for an eye exam.


Once causal agent has been correctly identified, it’s wise to convince customers that monitoring is a pest control product in and of itself, possibly the most important one. There are several “gadgets” to help diagnose tree problems, such as the resistograph, sonic tomography, mallets, hammers, probes and air spades, but perhaps the most useful is an arborists’ eyes … and experiences.

Being able to spot a problem as it is developing, or one that has been unattended to, is one of the most valuable pest control endeavors you can provide. Routine inspections are a worthwhile service and should be a part of the pest control package you offer clients.

Size and timing matter in terms of pest control; early and late stage larvae of bagworms are good examples. Photo by James Kalisch, UNL.

Size and timing matter in terms of pest control; early and late stage larvae of bagworms are good examples. Photo by James Kalisch, UNL.

Residual and need for retreatment

Every pest control product has a capacity to kill pests. However, products differ in relation to the length of time in which they retain the capacity to do so. For some pests, a short window of vulnerability exists due to the natural life cycle of the organism. Pine needle scale and pine sawflies are good examples of this, where insecticide applications are only effective during a two-week period at the proper life stage of the insect. For scale and sawflies, short residual formulations such as horticultural oils and insecticidal soaps offer efficacy without the need for residual. If applied at the peak of vulnerability, most sawfly or scale-infested trees can be effectively treated with one application.

Other pests, such as lilac/ash borers, are active for a much longer period of time, and therefore require insecticide treatments with longer residuals and multiple applications.

Damage from bagworms. Photo by James Kalisch, UNL.

Damage from bagworms. Photo by James Kalisch, UNL.


Even though the products you select are EPA approved, low toxicity in nature, and your technicians apply them in a careful and contentious manner, some people and various groups perceive them to be unacceptable.

It’s wise to have answers ready for those — potential customers or not — that object to the use of modern-day pest control products. A short and simple talking points message on sound and environmentally responsible pest control can assuage the doubting public.

Potential for environmental damage

The cost of damage to the environment is another factor to consider. In general, products that have the most capacity to cause harm to the environment are ones that have high initial toxicity, long residuals and capacity to kill a broad spectrum of organisms.

The capacity to kill a broad spectrum of organisms has long been an issue with mite control. For every undesirable mite species, there is also a beneficial one. Materials that are nonspecific enough to kill both beneficial and pest mite species are problematic because pest mites are usually able to regain population much sooner after the products are applied than beneficial organisms.

Despite your best intentions, it’s impossible to keep every bit of pest control formulation on your client’s tree or shrub. When applied on windy days or with the inappropriate spray equipment, pesticides can find their way to the street, down the storm sewer, and into our lakes, streams and groundwater. As you choose from the many pest control product options, consider their potential to cause environmental harm.

Need for equipment

Injected. Sprayed. Granular. As you consider the wide array of available pest control products, keep in mind which control methods you and your crew are familiar with. When you encounter a new product on the trade show floor or in an advertisement, it’s wise to think about how well it fits with your existing application equipment. Using product xx might mean that you have to buy a new piece of equipment … and maintain it. In some cases, the equipment purchase or the training required to use it will be well worth it; in other cases, not so much.

Inspecting and monitoring are a crucial "pest control product" to provide to your clients. Photo by Curt McLey

Inspecting and monitoring are a crucial “pest control product” to provide to your clients. Photo by Curt McLey

Consider the surroundings

The areas adjacent to the property where pest control products are applied are important as well. In the matter of tree risk assessment, these are called “targets,” namely people and objects that the tree or limbs could fall on. These spaces are another factor to consider when choosing pest control products.

Injection — Best for surroundings where spray drift could damage cars, houses, etc. Of course, a small amount of injury to the tree occurs as a result of the injection, so factor that in to the equation. If repeated treatments are required for control, other methods should be considered.

Basal — Best where surrounded by turf or mulch, not on a slope where the product could run off or be unevenly distributed. Basal applications are also well-suited for shrubs and small trees.

Topical spray — Best where thorough, uniform coverage is required. Of course, in windy conditions, off-target drift is possible.


Without a doubt, price is a factor. However, it’s only one of many. Low-cost products are advantageous for the obvious reason: they require a lower initial outlay of cash. More expensive products, especially ones recently placed on the market, must return product development costs to the manufacturer in short order. A good strategy to use to keep price in perspective is to create a spreadsheet for the purposes of selecting pest control products, and list all of the components mentioned in this article at the top of every column.

The surroundings of a property are a factor in the pest control product decision. PHOTO: JOHN C. FECH

The surroundings of a property are a factor in the pest control product decision. PHOTO: JOHN C. FECH

Consideration of effectiveness

With all these issues in mind, the best approach could be to start by considering effectiveness first, and then proceed accordingly. For example, let’s say that the top three recommended products for control of a given insect cost about the same and have similar residual activity. However, differences exist in terms of the spectrum of insect species that are effectively controlled. Because effectiveness is the bottom line, this information could be the deciding factor.

The severity of the problem and timing are always part of any pest control equation. For example, a few aphids on a small crabapple versus a longstanding bronze birch borer infestation are very different considerations. The aphids call for a topical application of a short-residual insecticide when noticed during the growing season, whereas the birch borers must be treated on the bark during the time of egg-laying or injected soon after the fact.

Modification of the landscape microclimate is another pest control option that applies. Though not an actual “spray it on the tree” product, applying mulch, monitoring soil moisture, and growing a ground cover over the top of the roots will go a long way towards lessening the effects of the borers.

From a timing standpoint, a blue spruce with small bagworms that are the size of a fingernail are much more easily controlled with lower toxicity materials than full-blown, large larvae with well-constructed bags.

When it’s all said and done, choosing pest control products is similar to other major decision-making processes in life. Taking the time and making the effort necessary to come to a well-informed decision will reap tangible dividends.