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Invasive insects are found throughout the United States and Canada in alarming numbers and have become a major problem in the past several years. Invasive shot hole borers have been targeting more than 300 tree species between San Diego and San Luis Obispo, California. Additionally, pine bark beetles have been relentlessly attacking trees in Arrowhead, Big Bear and other California mountain and foothill regions. Goldspotted oak borer, while spreading more slowly, has been decimating live oak trees north through Santa Barbara County.

All this activity currently is in California, but throughout the U.S., invasive insects such as Asian longhorned beetle, emerald ash borer and spotted lanternfly have become established and well known in just the last few decades. Millions of trees have died due to these infestations, with more than 100 million trees lost to emerald ash borer since 2002. It’s no wonder these invasive pests are a huge concern for Americans concerned about trees in their community.

Even so, while the problems with invasive species have received widespread media coverage, these reports can often be misleading, leaving the public confused about treatment options.

Current methods of insect control for trees

Several methods for insect control exist in the green industry, but when news about new invasive tree pests makes it into the media, it is often mischaracterized as a binary issue: the use of pesticides for large-scale spraying, or the loss of thousands of trees.

Pesticide sprays, as we know, cover not just the invasive insects, but the entire plant and surrounding area. This method impacts the overall environment, since nonhost plants and insects also are affected. Unfortunately, pollinators that are critical to the balance of our ecosystems are often negatively impacted by the spraying of large areas. In addition, topical sprays can be of limited utility and are not always a precise option.

Tree injections, on the other hand, are administered directly into the tree’s vascular system. Arborjet’s treatments are administered through a plug placed in a drilled hole, ensuring the product goes directly into the vascular system. The product then gets dispersed through the trunk, branches and leaves.

Tree injection as a method of delivering nutrients, insect control and disease control has been a common practice since the 1970s, and can trace its origins to the 12^th century. It has been used in several major cities and regions throughout the U.S. to great effect, eradicating insect infestations and protecting hundreds of thousands of trees.

Addressing injection misconceptions

Why, then, is tree injection often left out of conversations about treating invasive pests? There are several misconceptions about tree injections that should be clarified, including:

1. Tree injection is prohibitively expensive.
2. Tree injections take too much time.
3. Treatments aren’t effective and are harmful to pollinating insects.

Repeated use and decades of data have shown us how safe and successful tree injections are. They are cost effective in the long run, since each injection is only a few milliliters of product, and some treatments are active for two or three years. Treated trees also can provide protection to nearby untreated trees by lowering overall insect pest populations, resulting in further savings and greater efficiency.

Given the precision nature of injection, less product is used overall compared to a topical spray. Injectable formulations are far less diluted, which means faster work and easier transportation – no need for a large backpack or a truck for tank mixing on site. Additionally, with the proper technique, field tests have shown that even large trees can be completed in just minutes, and multiple trees can be worked on at once, meaning large-scale jobs can be managed efficiently. Product injected into trees remains in the wood and leaves, leaving the surrounding soil, water and air unaffected, thus reducing damage to off-target species.

University studies have shown that when correctly performed, tree injections provide minimal risk to pollinators. Pollinating insects can be protected from harmful side effects of treatments by ensuring the product is injected into the tree after it has finished flowering and producing pollen. Some products also have a very short half-life, meaning there’s no risk of the product remaining active the following spring.

Working for positive results

Tree injections have been effectively used in cities to protect trees on a large scale. In 2007, the city of Chicago experienced a huge outbreak of emerald ash borer, threatening the health of 95,000 public ash trees. At least 18,000 trees were injected each year, preserving more than 65,000 ash trees. Far more cost effective than replacing dead or dying ash trees, injection technology also helped to keep urban areas shaded while preserving neighborhood character.

New York City is another example of a large city that used tree injection to protect its trees from an infestation, this time by Asian longhorned beetle. By 2019, several of the city’s boroughs were declared clear of the pests, preserving thousands of trees. Additionally, New York currently treats more than 10,000 ash trees each year for emerald ash borer.

Conclusion

While other choices, such as sprays or tree removal, may be the best decision in some situations, tree injection should not be dismissed because of common misconceptions. Performed correctly, tree injections are fast, effective and targeted, and have minimal impact on pollinators and the environment.

The more information arborists have, the better they can inform customers and help educate the public and green industry about an important plant-health-care procedure. Tree injections should always be considered as a valuable option available to plant-health-care experts.

Kevin Brewer is the Northeast technical manager for Arborjet | Ecologel, as well as a Board Certified Master Arborist (BCMA) and Registered Consulting Arborist (RCA). He’s worked in the green industry for more than 20 years.

TCI Magazine’s Educational Sponsored Content is a sponsored feature available only to TCIA corporate members. This article is sponsored by Arborjet | Ecologel, a 23-year corporate member with headquarters in Woburn, Massachusetts.

Arborjet | Ecologel is a global leader in plant health care. Since the year 2000, the company has provided thought leadership, scientific research and sustainable products that have advanced the green industry. This innovative approach has led to significant advancements in tree care through trunk injection and Arborplugs along with advanced formulations for water conservation and plant nutrition. Driven by a deep commitment to customers, the company’s environmental stewardship protects trees, reduces water usage and develops sustainable products with people and the planet in mind.