There are many different wood conditions grouped under the term stain, with many different causes. The only one we need to really be concerned with here is blue stain.
This is a blue-grey stain of wood that can tend to being black. It is caused by ascomycetes or deuteromycetes that have dark brown hyphae. The way light goes through the wood, it ends up looking bluish grey.
The most common and well-known form of blue stain is found in conifers, especially pines, that have been invaded by bark beetles. The beetles either kill the tree or invade it as it is dying. They carry with them a fungus in a group we will just call by the genus Ophiostoma.
When the beetles attack, they inoculate the tree with their fungus. The fungus invades the wood, but especially the rays and the resin canals. The rays are heavily colonized. When you look closely at the wood, you can often see dark streaks where the resin canals were stuffed with hyphae. Such wood is common after salvage operations (harvesting recently killed trees), and when logs are stored after cutting under conditions that permit beetle attack.
One hypothesis on the relationship is that the fungus helps the insect by killing cells in the sapwood such as rays and resin canal cells. This reduces the host reaction against the beetle. Another is that the fungi may produce chemicals that are important in beetle maturation. Other things may be involved. In turn, the beetles provides the fungus with vectoring services. This is a symbiosis.
There are many different wood conditions grouped under the term stain, with many different causes. The only one we need to really be concerned with here is blue stain.
ReplyDeleteThis is a blue-grey stain of wood that can tend to being black. It is caused by ascomycetes or deuteromycetes that have dark brown hyphae. The way light goes through the wood, it ends up looking bluish grey.
The most common and well-known form of blue stain is found in conifers, especially pines, that have been invaded by bark beetles. The beetles either kill the tree or invade it as it is dying. They carry with them a fungus in a group we will just call by the genus Ophiostoma.
When the beetles attack, they inoculate the tree with their fungus. The fungus invades the wood, but especially the rays and the resin canals. The rays are heavily colonized. When you look closely at the wood, you can often see dark streaks where the resin canals were stuffed with hyphae. Such wood is common after salvage operations (harvesting recently killed trees), and when logs are stored after cutting under conditions that permit beetle attack.
One hypothesis on the relationship is that the fungus helps the insect by killing cells in the sapwood such as rays and resin canal cells. This reduces the host reaction against the beetle. Another is that the fungi may produce chemicals that are important in beetle maturation. Other things may be involved. In turn, the beetles provides the fungus with vectoring services. This is a symbiosis.
You're a symbiosis, Ellen.
ReplyDeleteEllen, I'm pretty sure you just turned into me for a second.
ReplyDelete