First report of elm canker caused by Pestalotiopsis mangiferae in the United States.
Chinese elm (Ulmus parvifolia) is native to China, Korea, and Japan and was introduced to the USA to replace the American elm, which is highly susceptible to Dutch elm disease. Cultivar Emmer II trade mark Allee elm (or Allee elm) is preferred by nurseries for its rich green foliage and beauty of bark. In the summer of 2011, a new disease was observed on Allee elm at a tree farm in Florida, USA. Approximately 1% of elms in the same farm and in residential areas in central Florida had similar canker-like symptoms consisting of tan to orange patches of decomposed and loose bark. These symptoms were observed on the main trunks often extending into branches of affected trees. Cankered sections of the trunk were often several feet in length and penetrated the wood to a depth just under the bark into the phloem. Based on morphological and cultural characteristics, sequence analysis of the rDNA internal transcribed spacer region, and pathogenicity tests, the causal agent was identified as P. mangiferae. This is thought to be the first report of P. mangiferae on an Ulmus species in the USA and the world.