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Tuesday - January 25, 2011

From: Pittsburgh, PA
Region: Mid-Atlantic
Topic: Trees
Title: A tree to replace a pin oak in PA
Answered by: Anne Bossart

QUESTION:

My 120 yr old pin oak has root and butt rot, 5 of 13 roots dead by pressure testing. I am in Pittsburgh PA. I want to plant a root rot resistant tree, either evergreen, fir or deciduous. The tree is 90' and 6' at trunk. It has to be cut down. Arborist recommends felling due to fall risk. Where can I get info about what to plant?

ANSWER:

What a heartbreaking situation!

Because the rot can be caused by many members of the Armillaria fungus family, the disease has a huge range and many plants are susceptible (or resistant) to varying degrees. So you will find a plant to replace that giant.

You don't describe the situation of the tree that will be removed or how big you want its replacement to ultimately be. The form of a large evergreen tree is very different than a large deciduous tree so if you are on a small suburban lot, a large conifer will ultimately cover the whole yard. Once you have determined what form of tree you would like, choosing one that is suited to your conditions (native to PA) and resistant to Armillaria will be easy, as the list will not be long!

Learn about the fungus on Wikipedia, this article by the US Forest service and check out this article on eHow.com. There are several links from the article you will find helpful. The list of immune plants they refer to in the article was produced by one of our Affiliates, The Theodore Payne Foundation for Wildflowers and Native Plants. Although they are situated in California, the disease is widespread and so you might try plants they recommend that are native to PA. You can generate a list of plants native to PA by visiting our Native Plant Database and doing a combination search for PA, the plant type (tree) and narrow the search according to the conditions on your property. We also recommend checking with your local agricultural extension service to see what advice they can offer and ask your "tree guy" his opinion.

According to the Wikipedia article, the only trees that are truly resistant are larch and birch (which are not mentioned because

By cross referencing those lists, here are some plants that might work:

Betula nigra (River birch)

Cercis canadensis (Eastern redbud)

Fraxinus americana (White ash)

Larix laricina (Tamarack)

You can also select fron the many maples, pines and firs native to your area.