Plant diseases are infinitively fascinating. This past weekend we saw excellent examples of galls on Jack Pine. There were pine trees with galls in early stages all the way through to nearby pines with what were clearly older galls – well developed woody growths on the stems.
A little bit of research revealed that these galls go by a variety of names – at least on the internet. According to Cornell University, a very credible and reliable source, the galls we saw are a symptom of “pine to pine gall rust” caused by a fungi – Endocronartium harknessii. Most plant galls are caused by either fungi, bacteria or insects. Just like oysters making a pearl around a grain of sand, a disruption or irritation in the plant produces extra material. In the case of plants, hormones are generally produced as a response to the fungus in turn stimulating extra plant growth. With these yellow galls, this extra plant growth provides a home for the fungus to produce spores and spread.
Our walks and hikes are such good opportunities to observe examples of the effects of different diseases on plants, I am reminded of long ago plant pathology courses. And if you are interested in this area too, you may be interested in the post on black knot.