Gibbago trianthemae causes Trianthema portulacastrum (horse purslane) blight in Pakistan

Abstract

Trianthema portulacastrum (horse purslane) is among the most noxious summer annual weeds in Pakistan. During June 2010-2012, a severe outbreak of leaf and stem blight was observed for the first time on T. portulacastrum in Pakistan. Symptoms on leaves and stems were examined as round to oval straw colored spots with maroon margins. As the disease progressed, affected leaves became chlorotic and dried up causing severe defoliation and withering of stems. The pathogen was identified as Gibbago trianthemae on the basis of morphology and cultural characteristics. A pathogenicity test was performed and Koch's postulates were fulfilled by re-isolation of the fungus G. trianthemae from diseased tissues of T. portulacastrum. This is the first report of G. trianthemae causing blight on T. portulacastrum in Pakistan. © 2013 Australasian Plant Pathology Society Inc.