Old Monkey
Treehouser
- Joined
- Mar 9, 2005
- Messages
- 8,764
We just finished our annual Horticultural Expo here in Boise. There were some interesting lectures and some that made me envy my old boss who was snoring two seats away from me. One that was quite interesting and a bit depressing was by Professor Whitney Cranshaw from Colorado State University. He talked about boring insects in our region. He has been working on something called Thousand Canker Disease which is killing all of our black walnuts out West. Its really a two organism attack. Small walnut twig borers are carrying a fungus called Geosmithia morbida that infects and kills the tissue around the borer. The fungus doesn't spread too far but their are so many of the borers that the end result is a girdling of the tree.
These borers and the fungus started out in the Southwest, New Mexico, Arizona and Mexico. There they have a minimal effect of the native walnuts. Somehow they spread north and the effect on black walnuts has been devastating.
Now they have been found in Tennessee. That means they have a toe hold in the native, Eastern black walnut stands. Professor Cranshaw feels that that it may take decades but that all the black walnuts are goners. He highly recommends that we do not move black walnut around as two firewood pieces could contain thousands of these very small beetles. The symptoms are flagging, the die back of top branches. If you see this, he feels that it is already too late and the tree will be dead in under three years. Chemical treatments are not proving effective at this point.
http://www.thousandcankerdisease.com/
These borers and the fungus started out in the Southwest, New Mexico, Arizona and Mexico. There they have a minimal effect of the native walnuts. Somehow they spread north and the effect on black walnuts has been devastating.
Now they have been found in Tennessee. That means they have a toe hold in the native, Eastern black walnut stands. Professor Cranshaw feels that that it may take decades but that all the black walnuts are goners. He highly recommends that we do not move black walnut around as two firewood pieces could contain thousands of these very small beetles. The symptoms are flagging, the die back of top branches. If you see this, he feels that it is already too late and the tree will be dead in under three years. Chemical treatments are not proving effective at this point.
http://www.thousandcankerdisease.com/