First report of leaf rust caused by Coleosporium solidaginis on Liatris pycnostachya (prairie blazing star).
In November 2017, several individuals of prairie blazing star (Liatris pycnostachya) were observed with symptoms of leaf rust and severe defoliation in La Marque, Texas, USA. Symptoms were distributed across multiple leaf surfaces with no clear correlation with leaf age. The abaxial leaf surface had circular to angular spots surrounded by brown necrotic tissue, and the adaxial leaf surface had bright yellow-orange rust pustules (uredinia) that were erumpent and 200 to 500 µm in diameter. Urediniospores were broadly obovoid, amber in colour, and ovate (30-35 μm long × 15-25 μm wide; n = 40) with echinulate spore walls 1.3-1.5 µm thick. Based on host information, morphological characteristics and sequence analysis of the 28S gene region of rDNA, the causal agent was identified as Coleosporium solidaginis. This is thought to be the first report of leaf rust caused by C. solidaginis on L. pycnostachya.