This winter I began the long and seemingly unending process of removing buckthorn from my property. We cut the clumps down to about 12 inches, and then we applied a herbicide called Tordon RTU to the stumps. Like I said, it seems a never-ending job, and this spring, we are still battling on with it. A couple of weeks ago, I began noticing that many of the leaves on the buckthorn had small orange spots on them. It seems to be affecting everything from seedlings to years old plants.

While stopping in at the Extension Office in North Branch the other day, I was telling our Master Gardener Coordinator about this, and one of the Chisago Soil and Water Conservation District employees overheard me. She informed me that the spots are a rust disease called Oat Crown Rust. It is caused by the pathogen Puccinia coronata var. avenae. Common buckthorn is an alternate host for the disease and provides a place for it to overwinter, allowing it to infect new crops in the next season. Those orange spots on the buckthorn leaves are a warning to wheat and oat growers that their crops could become diseased with this fungus. It also affects other cereal crops like barley.

  
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