Laura Arts
01/ 17/2011
Thousand Canker Disease A recently Recognized Threat to
North America Black Walnut
By Whitney Cranshaw and Ned Tisserat
This article is from the ISA (International Society of Arboriculture) newsletter under arborist news. I recently subscribed to in November. In the article they talk about a new disease that is affecting Black Walnut (Juglans Nigra) trees in the Western U.S. By a Fungus called, Geosmithia and the beetle that carries the fungus called Pityopthovous juglandis.
First off I want to give everyone a description of Black walnut for those that don't know what the tree looks like. It's a tall tree height of 70 to 150 feet. the bark is grey to black and deeply furrowed. Black walnut can be found in well drained bottoms and likes to grow in the open sun. Leaves are alternate with 15-23 leaflets. The fruit is round and brownish/ green which falls in October. The twig pith is black with small air pockets. The bundle scar right below the bud looks like a heart shaped monkey. With that, do you have a black walnut tree close to your home or in your backyard?
The disorder is called Thousand Canker Disease. It gets its name from the numerous cankers that form on the branches and trunk. It currently is so far east as southeastern Colorado. Increasing temperatures are a factor to eastern spread. It is important to be aware of this disease because the fact that Wisconsin has many black walnut trees and I'd hate to see them disappear like: American chestnut tree, American Elm, and Ash trees here due to the unawareness of the spread of disease. Black walnut is very prized for its beauty in wood products This disease happens and develops within the walnut twig. The twig beetle is yellow/ brown and is three times long as is wide. it is native to Southwestern U.S. and likes to tunnel and breed in branches greater than 2 cm in diameter. Branch cankers are visible until outer bark is shaved off to expose tunnels that the beetles create. Often the tree will die after two to three years after foliar symptoms are observed.
To not spread the disease it is important to not transport diseased wood to other areas. The fact that the beetle is so small it still can live in chopped wood. Right now there is no insecticides or methods to stop the spread of Thousand canker disease once it establishes itself in a community. I want to know is if butternut trees will be affected by this do to the fact that they are closely related? I want to know if the western U.S. is enforcing rules like here in Wisconsin. As in establishing quarantine areas that have this disease and firewood regulations or slogans that get the general public aware of this issue. The public are the biggest concern they need the most information. I had no idea that black walnut had a disease until this article came out and I'd hate to see such a prized wood go extinct. I hope this information has enlighten everyone to realize what's happening out west and to keep watch for further information on this current issue.
4 comments:
Laura,
Your enlightenment is fascinating. I haven't heard of this disease up until now. It almost seems as though it is getting to the point where all species are being nearly threatened by some kind of insect or pathogen. It is not uncommon in places around here for species like American elm and red oaks to grow up twenty feet high and then die. Ash trees in central Wisconsin are also about to face that same fate. I've grown accustomed to the early deaths of American elms. They still manage to survive long enough to pass on their seeds and reproduce. I guess it's not all bad for these things to happen since there is always something to take it's place. Just as long as they aren't replaced by invasives, the plant communities will continue to flourish. Nature always has a way to keep things in check as it did with American chestnuts years ago and with the currently progressing disease affecting multi-flora rose. I can not wait for a disease to come along and wipe out buckthorn. I've pretty much given up on fighting it, so that is my only hope.
We have a wonderful black walnut tree that we planted about 20 years ago. It's still only about 4" DBH, but really a big producer. The squirrels just love the nuts. I haven't seen any canker, but there are often some type of bug infestations on the leaves that don't damage the trees at all. I sent one down to Phil Peliteri in the UW insect lab and he said don't worry. After your post, I'll be watching out for other problems!
Laura,
I had not heard of this disease until I read your post. I am not sure if butternut trees would be effected by the thousand canker. I can say though that butternut is already being ravaged by butternut canker. Also, in WI where Black Walnut is mostly prevelent in the Southern 1/2, I have not seen an abundance of Butternut trees. Spatially, the Butternut may be safe.
I will be watching for signs of the thousand canker down in Belleville, WI south of Madison where I work on a property with a quite large B. Walnut plantation. To my understanding, tree diseases spreading across the landscape is quite a natural occurance. Sadly, we expodite the process by moving wood and not being educated on the newcomers. I will be on the look-out now. Thanks!
I also have never heard of this disease. There are many other common diseases around the midwest such as dutch elms,oak wilt and borers. By the sounds of it its not close to Wisconsin thankfully. I think that if the regulations prohibit them from transfering wood across boarders and to areas that are not effected we should be fine. However, there is always possiblities that people will not follow the rules and we could get the deadly disease which we do not need. I hope I do not see it anytime soon or while I pursue my career in Urban Forestry. Thanks for the knowledge on this matter.
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