DES MOINES, Iowa – With spring planting on the horizon and emerald ash borer (EAB) having already invaded 35 states, farmers are looking for the best way to combat the pest this year. 

According to the USDA Animal and Plant Health Inspection Service’s (APHIS) Emerald Ash Borer Program’s latest state and county data, as of April 24, all 35 states have documented confirmations of EAB infestations – and all are within the federal EAB quarantine area. 

“Some more recent first time detections in bordering states include North Dakota (spring 2018) and Nebraska (summer 2016),” Mike Kintner, Iowa Department of Agriculture and Land Stewardship (IDALS) EAB and Gypsy Moth outreach and regulatory coordinator, and entomologist, told Farm World. “These findings involved Sioux Falls and Omaha, respectively.”

These states (and the District of Columbia) include: Alabama, Arkansas, Colorado, Connecticut, Delaware, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, West Virginia, and Wisconsin.

The EAB is a small, metallic-green beetle that attacks and kills ash tree species. In its larval stage, the EAB bores beneath the bark, disrupting the movement of water and nutrients within the tree, with infested trees typically dying within two to four years.

Native to China, Mongolia, North Korea, South Korea, Japan, Taiwan, and the Russian Far East, the EAB was unknown in North America until its discovery in southeast Michigan in 2002.

Ash trees infested with EAB might exhibit canopy thinning, woodpecker damage, water sprouts from the trunk or main branches, serpentine (“S”-shaped) galleries under the bark, vertical bark splitting and 1/8 inch D-shaped exit holes.

 “Woodpeckers like to eat EAB larvae beneath the bark of ash trees,” Kintner said. “Despite it being winter, woodpecker damage is an indicator EAB may be lurking in a tree.”

The adult beetle can spread naturally by flying short distances to area host trees; however, the more threatening long-distance spread is by human-assisted movement. 

Beneath the bark, larvae can unknowingly be transported in infested wood products such as firewood. People are encouraged to use locally-sourced firewood where they are going to burn it.

In Iowa, a federal quarantine, enforced by the USDA, prohibits the movement of regulated articles such as living and dead material from ash trees and all hardwood firewood out of the state into non-quarantined areas of other states, according to the IDALS.

If a landowner is interested in protecting a valuable and healthy ash tree within 15 miles of a known infestation, he or she should treat through mid-May.  Kintner said individual, healthy ash trees can be protected with insecticide treatments, spring through mid-September, depending on the product and method of application.  

“Systemic insecticides are the most effective way to protect ash trees from EAB and can be applied through soil drenches and granules, soil injection, trunk injection, or basal bark sprays,” Kintner said. “DIY methods are limited and need to be applied on an annual basis, during the correct timeframe.  

“For hired help, commercial pesticide applicators have more options with applications lasting one or more years,” he added. “Preventative treatments are suggested for ash trees within 15 miles of a confirmed EAB site because of the risk of attack.”

“The USDA biological program has guidelines for choosing sites and they make the final determination whether or not to approve a site based on a number of criteria,” he added. “If approved, the biological agents (parasitoids) are provided to the cooperator at no cost.” The parasitoids used are stingless wasps. Kintner said parasitoids are released during the summer months. 

“Two species attack the larvae (the immature stage) of EAB under the bark, while the third species seeks and kills EAB eggs tucked away in the bark crevices of ash trees,” he said. 

He said the parasitoids were produced and supplied from the APHIS, Plant Protection and Quarantine (PPQ) EAB Parasitoid Rearing Facility in Brighton, Mich.

“The biocontrol effort is a long-term management strategy and is not served for saving existing large ash trees in the landscape; it’s about the future generations of ash trees,” he said. “Biocontrol is not for eradicating EAB.”  

Because there are multiple factors to take consider when looking at EAB treatment options, information should be obtained locally from organizations such as a local state land-grant university, local extension service, or private arborists. 

“This ensures that all applicable state and local regulations or current recommendations are taken into consideration,” Suzanne Bond, APHIS assistant director of public affairs, told Farm World.

“We continue to work with state cooperators to detect and control the pest in order to safeguard America’s ash trees,” she added. “Strategies focus on biological control and trapping surveys, combined with public outreach and education initiatives to promote program support and compliance.”

The APHIS works with state, federal, and other partners to detect and manage known emerald ash borer (EAB) infestations. Bond said the Emerald Ash Borer Program Report provides announcements, the status of EAB in the United States, links to maps, and other useful links on the USDA APHIS PPQ EAB program. 

She added the APHIS also recommends signing up to the Stakeholder Register to automatically receive the EAB Program Report. To view the federal EAB quarantine map, visit: https://www.aphis.usda.gov/plant_health/plant_pest_info/emerald_ash_b/downloads/eab_quarantine_map.pdf

The public can report EAB by calling the EAB Hotline at 866-322-4512.