 Another stem disease that we're going to talk about is Dutch elm disease. Now this particular disease has an insect vector associated with it. So many of the things that we're looking for to try and identify Dutch elm disease are actually looking at the evidence that the insect has been there. One way to certainly figure out if you have Dutch elm disease is one of the first things that you may see is you have an elm leaf that is wilting. And that's a classic symptom of Dutch elm disease. It will cause wilting and sometimes it will cause yellowing of leaves and then wilting and then the tree. What's happening is the fungus is blocking the water conducting vessels so the tree can't bring water to the tree. Excuse me, the roots can't bring water to the tree. So we may see wilting on the leaves. The other thing we may see if you take a small branch and you peel away the bark you'll see some staining. What's happening here is the fungus is staining the internal xylem and it's gray to brown. If we were to have a branch here that did not have Dutch elm disease it would be creamy pure white. So this staining here is very common symptom of Dutch elm disease. The other thing associated if you look closely we see some insect galleries and these particular insect galleries are from the insect that is actually moving the fungus around. This is actually scolitis multistriatus and it's called that because it makes the gallery that goes up and down with the wood and it lays its eggs and all the insects scatter and it's multistriation. We have another example here. There's also another insect vector associated with this and this is the native elm bark beetle. Unlike where the scolitis multistratus goes up and down the native elm bark beetle goes across the bark. So what we have here is the scolitis multistratus going up and down and then we have the native elm bark beetle going back and forth and this is on the inside of the bark. So when you see these two insect galleries associated with elm bark you can pretty much assume you have Dutch elm disease and here's the inside where we remove the bark and you can see all the galleries and we have both multistratus on here going up and down and we have the native elm bark beetle going back and forth and we also have a very teeny tiny insect which if you were to take a hand lens you could see the scolitis multistratus tiny little insect associated with Dutch elm disease. So we would see wilting on the elm. We may see yellowing on the elm. We may see staining on the xylem and we would see the gallery, the two gallery patterns up and down and across and that would be Dutch elm disease.