As a Master Gardener we are frequently presented with problems that various gardeners face. Sometimes people will bring in pictures or even samples of the plant they are dealing with. Sometimes figuring out the problem is simple, other times definitely not.
We have learned to ask a series of questions to help tease out clues which may help us diagnose the problem. We also have many references and resources which we can use to help us narrow down the possibilities.
When we were in Germany we came upon what appeared to be an outbreak. First describe what you see. The manifestation seems to involve only the trunks of trees not the branches. The problem seems to be an enveloping, raised, almost furry growth. The coloration is quite variable, not only from trunk to trunk, but within a single trunk. We also saw that the outbreak did not limit itself to a single species but seemed to cross into several genera in the area of older Wiesbaden.
Next find out the history or progression of the symptoms.Find out what the gardener has done or not done. I didn't speak German well enough to ask questions, but I suspect if I had the answer would have been that the manifestation appeared overnight. Lastly, hit the books! In the last few years there have been similar outbreaks in cities and towns across the globe. They have even experienced an outbreak on the campus of UC Davis.
The manifestation is called..... yarnbombing. Some industrious knitters knit up multicolor sleeves which are generally put up and sewn together in the dead of night. The decoration is not necessarily limited to trees; we saw a few lamp posts adorned as well. It's a wonderful surprise for a town's inhabitants. In the dead of winter, under generally gray skies, it made for a wonderful pop of color.
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