First report of black leg of hydroponic Basil in the United States caused by Plectosporium tabacinum.
During August 2007 and January 2008, compact sweet basil (Ocimum basilicum cv. Genovese) plants grown hydroponically in Indiana, USA, showed dark, irregular, stem lesions extending 2-3 cm above the interface of the nutrient solution. These necrotic stem lesions (black leg) observed on 20-30% of the basil plants caused very weak, brittle stems so that they could not be marketed fresh. Although no wilting was noted, reduced plant height was observed. Diseased plant samples were studied, and morphological and molecular analyses identified the pathogen as P. tabacinum [Monographella cucumerina]. This is thought to be the first report of P. tabacinum causing black leg and reduced growth on basil in the USA and the first report of P. tabacinum on hydroponic basil.