Dutch Elm disease
Hi- We have an old Elm (about 50 ft. high, 4 ft diamter with large canopy) in South Mpls that we have had profesionally treated for Dutch Elm prevention the last 10 years (every 2 years). Out next door neightbor has a similar sized elm and that has also been treated for dutch elm prevention regularly at the same time as ours. The two trees are aprox 25 ft apart and their canpapies overlap some. The neighbors tree looked very poor and suspect this spring and when we went to have the trees both treated in May the tree specialist confirmed that our neightbors tree had dutch elm. He cut a ring into the diseased tree near the bottom to try and help prevernt the ditch elm from spreading downward and di not treat either tree this spring stating it would do no good this year and might make it worse for so and all we could do it was hope we got lucky and it didn't spread to our tree but said odd were slim. The neighbors disesed tree has looked worse and worse though the summer and they are supposed to be arranging to have to it taked down but have not yet. Is there anything we can do to help our odds of our tree not becoming diseased? Specifically, there have been several dead branches up high on our tree for years that we have never had trimmed. Would it help to have these trimed?
Hennepin County Minnesota
Thank you for the question. The Dutch elm fungus can't be transmitted to your tree through air or water, but rather is spread via bark beetles or through connected roots systems that can graft together. Your tree could get the disease from the beetles or grafted roots from your neighbor's tree.
The best way to control the disease is to make sure that all dead or dying wood with intact bark is cleaned up and discarded because this reduces breeding sites for the beetles. Do not move the wood with intact bark off your property. It should be chipped, buried, burned, or buried. Moving the wood off your property risks spreading the disease. If you have dead or dying branches, a certified arborist should remove them and check for the disease. Several publications also recommend having infected tree roots severed before removing the tree to prevent transmitted the disease through root systems.
Read more here:
Thank you for contacting Extension.