Moving Beyond 'Spray-Centric' Plant Pest Management

If only trees could talk, especially when they’re unwell. They could tell us where it hurts or why they’re looking a little peaked. Often, when a tree or shrub is ailing, the cause isn’t immediately obvious. Arborists or plant healthcare technicians must do a fair amount of investigative work to pinpoint the problem. Sometimes, that means taking an up-close look through tissue sampling. A laboratory analysis can be key to diagnosing the issue and developing an effective treatment plan.

Understanding Integrated Pest Management

Identification and diagnosis can involve a variety of factors, including fungal and bacterial diseases; arthropod pests; chemical and physical causes of plant disorders; and impacts from rodents, birds and nematodes. Understanding the specific cause of damage to a tree or shrub is critical for establishing a proper integrated pest management (IPM) recovery plan.

IPM is an ecosystem-based approach to landscape plant health care. It aims to sustain plant health and performance through strategically implemented actions designed to minimize unintended human, ecological and environmental effects. A successful IPM program begins with regular landscape inspections to identify:

           •  Underlying plant health issues

           •  The pests and diseases present and their densities

           •  The damage caused or potential damage

Treatment Strategies and Monitoring

Treatments are applied when damage reaches an injurious level, although there are times when immediate treatment isn’t necessary or a proactive approach is more suitable. 

Armed with this information, a variety of management approaches (e.g., biological, cultural, chemical) can be combined to maximize long-term pest management success. Many innovative strategies aim to limit the use of conventional, broad-spectrum products that can negatively affect non-target plants or beneficial organisms. For example, growing degree-day calculations—used to track when specific pest species are active in different geographic areas—are critical for proper treatment timing. 

Innovative Solutions:
Beneficial Insects

Exploring the efficacy of beneficial insects, such as natural predators of pests, is vital. These insects play a crucial role in all-organic approaches when needed. Trees and shrubs near water generally cannot be treated with aerial foliar sprays due to potential drift into the water. Similarly, areas with heavy human or vehicular traffic, such as parking lots and recreational parks, may not be suitable for foliar applications. In these situations, beneficial insects become a valuable tool.

Trunk Injection and Pruning for Tree Health

In the Midwest, trunk injection applications are a common method for protecting native trees from serious threats like Dutch elm disease and emerald ash borer. Emerging techniques, such as injecting into the root flare instead of the trunk, have been shown to reduce tree wounding, enhance uptake and promote more even crown distribution. These systemic injections often provide months or years of protection, while foliar sprays typically require multiple applications each year.

Pruning is also an essential aspect of IPM. It can remove dead, weak or decaying branches, while structural pruning promotes healthy future growth and form. Proper pruning helps trees defend against potential insect and disease threats. Improving air circulation through pruning can also reduce fungal growth. Rejuvenation and renewal pruning fosters new growth, removes weak or diseased branches, and maintains the desired shape and size of the tree.

Expert Care for Healthy Trees and Shrubs

Each situation requires careful consideration of available treatment methods, and arborists should recommend the most appropriate course of action. Ongoing evaluation of new techniques and materials is essential, as is training plant healthcare specialists to provide responsible, sustainable management for the health of landscape trees and shrubs.

M.D. Skeet (“Skeet”) is an ISA-certified arborist and commercial arborist representative in the Bolingbrook office of Bartlett Tree Experts. Bartlett operates five offices serving Chicagoland, Wisconsin and Indiana, with more than 165 offices nationwide. For more information, call 630-960-4001 or visit Bartlett.com.