Emerald Ash Borer
Emerald ash borer, an exotic insect responsible for the loss of more than 100 million ash trees in the United States over the past two decades, has now been discovered in Sioux Falls. This is the first confirmed infestation in South Dakota.
Emerald ash borer (EAB) was found in northern Sioux Falls. The South Dakota Department of Agriculture received confirmation on May 9 that the insect is indeed EAB. The confirmation was made by the Animal Plant Health Inspection Service (APHIS), a division of the United States Department of Agriculture. The infestation so far appears to be confined to a relatively small area. The South Dakota Department of Agriculture is conducting surveys to verify the extent of the infestation.
Emerald Ash Borer
The emerald ash borer is a small beetle that was accidentally introduced from East Asia into the Detroit Michigan metro region sometime during the 1990s. Since that time, it has spread out into 32 states and three Canadian provinces including Minnesota, Iowa, and Nebraska. The emerald ash borer has killed nearly 100 million ash trees killed since the beetle was discovered in this country.
The larval (worm) stage of the insect feeds in the food-conducting tissue of the tree’s trunk severing the flow of food from the leaves to the roots. Infested trees usually survive for about five years before dying from the continual attacks.
Our black, green, and white ash trees and their cultivars are all susceptible to attack. Emerald ash borer does not attack mountainash or ash-leaf maple (boxelder). These trees are not related to ash.
All ash trees have a compound leaf, meaning its leaves are divided into smaller leaflets. There are usually 5 to 9 leaflets. The compound leaves are arranged across from one another along a shoot.
The insect was detected and confirmed in South Dakota in May 2018. The infestation is located within the northern portion of the city of Sioux Falls. This is the only known infestation in the state at this time.
The answer is yes unless a tree is periodically treated with an insecticide indefinitely. Typically, a community loses all their untreated ash trees within a ten-year period following detection. Tree owners who live in Sioux Falls should consider treating their individual trees for this insect. It is not practical for large plantings.
There is no need to call the City, Cooperative Extension, or the SD Department of Agriculture to inspect your ash tree if you live within the city. If you want to protect your ash tree, it should be treated.
The most effective treatments for mature trees, those more than 6 inches in diameter, are treatment applied by commercial applicators. They have the equipment and chemicals to properly treat your tree.
Trunk injections can begin after the tree’s leaves have opened and until the end of June. Injections during this time provide the most effective protection. The injections will need to be repeated every 2 years until after the outbreak is over, approximately 10 to 12 years. After that time the period between treatments can lengthen to 4 years or more. The cost of treating a tree generally ranges from $150 to $350 for trees between 10 and 25 inches in diameter.
The emerald ash borer is attracted to fresh pruning wounds so do not prune your ash trees between May 1 and September 1. Ash trees should not be removed during this same time as adult beetles can emerge from logs and brush as it is being transported.
After September 1 until the following May 1 the insect is inside the tree, so ash tree can be pruned. Ash wood and brush can be moved during this time, but it still must remain within the quarantine area.
There is a quarantine for Minnehaha, northern Lincoln (north of Hwy 18) and northeastern Turner (north of Hwy 18 and east of Hwy 19) Counties. No ash trees nor any ash brush, logs, or raw wood products such as ash firewood should be moved outside of this area. Contact your state (605-353-6700) or federal (605-244-1713) official prior to moving any of the above items outside the quarantine. Since firewood is difficult to identify to species, the restriction on firewood pertains to all hardwoods, not just ash.
If you are within the quarantine area the same restrictions for the movement of ash and firewood apply. Tree owners should consider treating their ash trees within the next few years as the insect will spread out beyond Sioux Falls.
There is no need to treat your trees nor are there any restrictions on pruning or movement of ash wood. However, ash tree owners may want to inspect their tree for signs of an infestation.
Infested ash will have their sections of their bark shredded off by woodpeckers searching for the larvae. If the bark is pulled off these trees near the woodpecker pecks, there will be S-shaped tunnels on the wood’s surface. These narrow tunnels, about 1/8-inch wide, will be packed with sawdust. There may even be white, flat, legless larvae (about 1/2- to 1-inch long) in these tunnels. Another possible sign of an infestation is 1/8-inch D-shaped holes along the trunk where the adult beetles have emerged.
Dr. John Ball, Forest Health Specialist, SD Division of Resource Conservation and Forestry/Extension Forestry Specialist, South Dakota State University, phone 605.695.2503. email firstname.lastname@example.org