First report of charcoal rot caused by Macrophomina phaseolina on sunflower in Illinois.
During field experiments in Illinois, USA, in September 2009, silvery gray, girdling lesions on the lower stems and premature death were observed on sunflower cv. Mycogen 8C451. When lower stems and roots were split open, the pith tissue was compressed into layers. Black microsclerotia were present on the outside of the lower stem tissue and on the stem wascular tissue. The pathogen was identified as Macrophomina phaseolina based on morphological, genetic (ITS) and pathogenicity tests. This is thought to be the first report of M. phaseolina infecting sunflower in Illinois, USA.