When it comes to pest control for woody plants, there are two approaches. Actually, three. There is preventive care, reactive care—and a hybrid of the two.

Perhaps an anecdote from another industry will provide an instructive perspective. I have a good friend who is a maintenance technician in a large hospital complex. Over the years, he has observed that there are two methodologies used in various parts of the hospital:

  • A. Workers who simply respond to work orders to fix broken equipment, and
  • B. Workers who routinely walk the floors, establishing relationships with head nurses and department heads, inspecting equipment, talking and learning from the installers of new equipment as well as responding to work orders.

My friend falls into Group b. He feels it’s the preferred approach, as he gets to know the special features of the equipment, has a feel for its useful life and can almost predict when repairs or replacements will need to be done. Some of his co-workers in Group b spend quite a bit of time doing preventive maintenance such as replacing HVAC filters and lubricating door hinges.

While this may not be a perfect analogy, it serves as a good lead-in for pest control in tree care. In our industry, Group b is called Integrated Pest Management (IPM) and Plant Health Care (PHC).

“See-through” trees are important immediate action-required items on inspection reports.


Is there really a difference?

In short, no. While most definitions cast IPM as focusing primarily on limiting damage from insects, weeds, diseases, vertebrates and abiotic factors and place PHC in a holistic, cradle-to-grave sense, there’s a huge amount of overlap between the two approaches. The line separating the two is about as grey and blurry as it can be.

Though each can be classically defined and attempts can be made to keep them separate, both can be interpreted, adjusted and implemented for good – and for the ultimate goal of installing and maintaining healthy trees in the landscape for amenity, noise reduction, energy savings and other environmental benefits.

Are you still in doubt? If so, consider these discerning questions:

  • Is either exclusively a one-year or short-term approach? No.
  • Is either strictly reactive rather than preventive? No.
  • Does IPM rely on healthy plants to be successful? Yes.
  • Does PHC rely on effective pest control techniques? Yes.

Yet, some arborists and tree care workers may claim that IPM is multi-strategy pest control and as such is just a part of PHC, while others may assert that the components of PHC are IPM-based: that monitoring, tree selection, right plant/right place, meeting specific plant requirements and providing good cultural practices are actually pest control strategies.

The more that individual points are raised, the more they sound the same. For example, if a crabapple tree routinely becomes infected with fireblight, is it due to being planted in the wrong place in the landscape, a repeated splashing of spores, sloppy pruning practices, cultivar susceptibility, ineffective spray technique or incorrect fungicide selection? As well, is that IPM or PHC?

Instead, another approach is to combine them together and utilize all appropriate principles and practices for tree health.

Show Me the Money?

Sure, the combination of PHC and IPM sounds great, but is it profitable? In a business sense, profit equals gross money received minus the costs of doing business.

  • On the income side, IPM and PHC programs may not be perceived as having a high value, at least in some parts of the country or by some frugal customers. In these situations, there is a need to communicate the benefits outlined above in exchange for the costs. Some clients will get it and be convinced and others simply will not. After all, what is a rare coin worth? Really, only the perceived value… or what someone else is willing to pay for it. Otherwise, it’s only worth a nickel, quarter or dollar. It’s up to the arborist, tree care worker and company to impart the perceived value into the minds of the buyer.
  • On the cost side, it’s important to be honest and call it what it is. There are significant costs: the need to pay the inspectors, the need to pay for developing diagnostic capacity, the costs of monitoring equipment, etc., as well as all the usual stuff like trucks, insurance, advertising, bookkeeping, tools and licensing. In some cases, however, along with the costs comes the opportunity to make money on services and treatments after each monitoring session as well as charging a reasonable fee for each inspection, or an annual fee that covers all monitoring visits for the season.
  • When you get right down to it, IPM and PHC, or the combination of the two is a clearly advantageous approach to the standard “spray and pray” or “react to problems after the fact” routine. It offers flexibility for the customer, a moneymaking opportunity for the arborist and, best of all—common-sense health care for the tree.

IPM/PHC combined

No matter what you call it, there are many components involved in caring for trees. They should be utilized before planting, during planting, in the initial year of life and in every year thereafter. Success is directly related to the extent that each is implemented.

One reason IPM conveys an important mind set is that the key word is “integrated,” in that it communicates that there are many components to the methodology, and that they work together to produce the desirable outcome. That certainly is the case. The elements below produce an overlapping or almost synergistic result.

Selection: Selection depends on the intended purpose – shade, ornamentation, fall color, flowering, screening, desired size and the history and layout of the site. Often, a site contains poor soils or is prone to disease development, which often can be addressed through species or cultivar selection.

Placement: For each tree species, there are poor, acceptable and preferred locations. Many factors are involved, including sun/shade exposure, considerations for leaf debris dropping, the separation of turf and ornamentals, wind patterns and proximity to other trees. Perhaps one of the most common mistakes is placement of a large tree in a small front yard.

Priorities: Considering the property as a whole, it’s advantageous to identify high, medium and low areas of importance for tree installation and maintenance. As various sites are chosen, it’s helpful to rely on area-specific resources for selecting and placing desirable species. Local arboretums and botanic gardens tend to be quite helpful; some local utility companies also offer good advice as well in this regard. In some instances, simple sketches can be prepared for the client that assist with prioritization.

Sphaeropsis/diplodia tip blight is a good example of a disease to be monitored over time.

Planting specifics: Possibly the most overlooked part of the planting process is the context for root and soil interfaces. If the soil in the root ball and planting site are roughly the same in terms of pH, texture, structure, fertility level and drainage capacity, all is well and the tree will usually get off to a good start. But, as is more often than not the case, there is a difference in any of these factors, the tree will suffer from dissimilar conditions. One of the most common is organic matter content: If the tree root ball is rich, loose and fertile and the site is heavy clay, tight and drains poorly, then the roots tend to rot and/or remain in the hole and circle rather than expanding laterally into the landscape.

Overcoming problems such as these is difficult, and directly impacts IPM and PHC. A critical concept to consider is planting area vs. planting hole. If big differences exist between newly acquired root mass and existing soils, the planting procedure should shift away from planting holes to areas of installation, where large expanses of soils are amended to create uniformity between the two. If large-scale modification is not feasible, then existing soils should be used exclusively, rather than filling the hole with organic matter, sand, bark or other amendments.

Is it an isolated or broad, landscape-wide cause? You only know when you look deeply.

Preservation: Trees that are in good health when planted have a good chance of success in the landscape if cared for with essential practices of mulching, irrigation, weed control and nutrient supply. Keeping the soil cool and moist, free from competition with grass and broadleaf weeds, preventing mowers and other turf maintenance equipment away from the trunk and soil sampling for nutrient need are key steps along the way. Going forward, customized maintenance plans should be developed that take the specifics of the tree and site into account.

Performance: Performance is the quintessential merging of IPM and PHC in that the key action involved is an evaluation of the previous and current health and vigor of the tree. Specific indicators include the rate of growth, the presence/absence of chlorosis, flowering potential/extent and density of foliage and stems. Quite simply, it can be characterized by a rating of “how it is growing,” both in terms of appeal and sturdiness.

Along with vigor, another performance characteristic is the relationship with other plantings such as the turf, flowers, groundcovers, shrubs and vegetable plantings. In most landscapes, all of these plants share the same root zone, particularly if the smaller ones are growing under the overstory trees. For example, if high pH is causing a river birch to struggle, chances are good that other sensitive plants such as spirea or filbert growing nearby also will be affected. The care of each plant in a landscape can affect the health of all plants in that landscape.

Another factor involved with performance is the condition of a particular specimen, specifically in terms of hazard awareness and risk assessment. Regular inspections are crucial in determining the actual health of a tree – a healthy-looking veneer of foliage and flowers could be covering up internal decay and insect tunneling, which can cause real problems in the near future. It’s crucial that, in addition to noting specific pests and abiotic factors, “targets” (aka people and property) are identified and recommendations for treatment and/or removals assembled and then communicated to the property owner.

No outer symptoms of heartwood decay were evident before this catastrophic tree failure. A thin veneer of outer bark was intact.


Construction damage: Actions that are taken before, during and after nearby construction activities can have a significant influence on tree health. If it’s known that a certain tree will be affected by soil removal, trenching or compaction, prevention steps often can be made. Utilization of fencing, re-routing, mulch applications, bridging and other techniques can minimize damage to the roots and trunks of valuable trees. As well, a recovery plan should be implemented that involves keeping compounding influencers away from the tree(s) being impacted.

Specific pests: Monitoring for specific pests should be integral to the process and conducted on a regular basis – either monthly, seasonally or yearly, depending on the budget and extent of the plantings. Diagnosticians have their own approach, but regardless of whether it’s a quick focus on the “trouble spot” or a 360-degree, walk-around tactic, the overall method must be thorough and consider all plants, soils and cultural practices being conducted on the property – and in a perfect world, the neighboring properties.

Diagnosis is a skill like any other: Learning a language, playing the guitar, interviewing for a job – it has to be learned and practiced to be effective. The best place to start is with a thorough understanding of how trees grow and how they’re supposed to look and function, then to start considering well-known maladies commonly associated with the particular species of tree being diagnosed, finishing with the observed surrounding influences that are germane to the site. Fortunately, product suppliers, university extension faculty and other arborists are good sources of diagnostic assistance.

Tailoring/customizing: Each landscape is different: different client incomes, different client goals, different tree problems, different soils, different neighbors. As a result, there is no “one size fits all” program. The best approach is to start with a basic monitoring schedule and add to it based on the interests and goals of the property owner.

The additions can be simple or complex, with each program enhancement presented with the goal in mind of creating and maintaining a quality landscape with healthy trees.

Connect with Tree Services: Like us on Facebook, Follow us on Twitter