EAB AND ASH RUST NOTES

In light of recent news coverage about Emerald Ash Borer (EAB) and a recent outbreak of ash rust we want to clarify the difference since both affect ash trees. EAB is an exotic beetle that was imported to the U.S. from China by accident in 2002. EAB has been responsible for the destruction of millions of ash trees in twelve states with the largest concentration found in Ohio and Michigan. EAB only attacks the Genus Fraxinus (White Ash, Green Ash, Autumn Purple Ash are among the most commonly planted ash trees in this genus) and will not attack Genus Sorbus (Mountain Ash). EAB is not in Nebraska and we do not know when or if it will arrive to our state. The most current information about EAB is located on the USDA Forest Service web site www.emeraldashborer.info.

A flood of ash leaf samples showing signs of rust have been arriving at our store recently. Ash rust, is a fungus (Puccinia sparaganioides) that appears on the leaves and green twigs as small, round, orange bumps giving the tree the appearance that it has caught measles. Ash rust does not harm the tree and is not related to EAB. Once symptoms of rust appear on the tree, treatment is not a viable option. To prevent this fungus a fungicide needs to be applied just as the leaves come out in the spring, but again, the disease is rarely destructive enough to warrant special control measures. It is difficult to predict if ash rust will be a problem next year. The University of Nebraska-Lincoln Extension has ssposted a fact sheet outlining the disease in more detail: http://extensionhorticulture.unl.edu/Current/AshRust.shtml

If you have any questions or concerns about your ash, or any other trees in your landscape please know that you can visit our store to for more information. In order for us to better diagnose your tree’s aliment please provide us with a fresh sample; a branch that is 6”-8” long with both the good and bad symptoms showing. Digital pictures are always welcomed; however, we are not always able to see the finer details that could lead to solving the problem.

Scott Evans
Garden Shop Mgr.
Mulhall's Nursery
Phone: 402.496.0700
Fax: 402.547.5003

Please Read Before Buying an Ash

Emerald ash borer is a threat to the ash population in the state of Nebraska. A clearing house for information about EAB is the website, www.emeraldashborer.info. Here is an excerpt from their home page, “Emerald ash borer is an exotic beetle (emerald green in color) that was discovered in southeastern Michigan near Detroit in the summer of 2002.... Emerald ash borer probably arrived in the United States on solid wood packing material carried in cargo ships or airplanes originating in its native Asia. Emerald ash borer is also established in Windsor, Ontario, was found in Ohio in 2003, northern Indiana in 2004, and northern Illinois in 2006.”

The insect attacks all varieties of ash. The adult insect can travel only about ˝ mile on its own. It can travel great distances though in infected wood. Transporting firewood from infested areas seems to pose the greatest threat of spreading EAB to un-infested areas. Many things are being done to slow the movement of the insect, including state and federal quarantines on ash nursery stock and firewood movement from infested states, and work on ways to kill the insect where it has been established.

Ash is a major part of the Nebraska forest. If EAB were to become established here, the effects could be devastating, not just to the trees planted recently, but to the millions of ash trees across the state. Our main focus therefore is to make everyone aware of the pest so everyone can help us prevent it from coming to Nebraska. Since the insect can only travel about ˝ mile by itself in its lifetime, it will not get to Nebraska by itself. If it gets here, it will be carried in on infected wood. Through discussion we have had with the USDA and the Nebraska Dept. of Agriculture, we are confident in the procedures they have in place to prevent EAB from coming into the state on nursery stock. (Mulhall’s has plenty of Nebraska grown ash in our fields.) Secondly, Mulhall’s is working with local, state and federal regulators and industry associations to encourage an ad campaign informing campers of the hazards of moving firewood and to develop rules about the movement of firewood. As well, we are trying to instruct our customers, via signs and our website of the potential harm of the insect and the need to avoid moving firewood. By slowing the progression of EAB, we are hopeful that pesticides will be developed to control the pest long before it gets to Nebraska.

The ash remains a wonderful tree for the plains. Because of the threat of EAB, ash prices have dropped significantly across the country. Our prices on ash trees this year will be considerably lower than previous years. Customers and clients will be able to get more tree for the dollar by selecting ash. Mulhall’s will continue to sell ash trees to our customers, but we want to make sure our customers know about EAB before they decide to buy an ash. We will also continue to encourage diverse plantings, which always are best, regardless of which pest we are battling.

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