The thing is about 15-20 years old. I have trained to to go back and forth across to fill in a 50 ft. metal fence. It’s never grown full sized grapes - just some bb sized things, but the foliage has been just fine. This year, I’ve got some stretches of several feet along the vine that are not growing leaves at all. There are a couple of buds that grow a little, and then they die. Added to that is the fact that near the trunk, there are several spots of a strange, yellow exudate. They appear in elongated spots, parallel to the direction of growth of the vine, about an inch or so long, and they’re sort of foamy. I know this is little to go on - but does that sound familiar to anyone? Any ideas on what the problem is, and how I might address it? Thanks.