First report of a leaf spot caused by Boeremia exigua var. linicola on autumn sage (Salvia greggii) in Italy and worldwide.
During the autumn of 2014, in a mountain garden located near Biella, northern Italy, a leaf spot was observed on 12-month-old plants of Salvia greggii, autumn sage. All plants grown in the garden were affected, with 20-30% of leaves showing symptoms. First symptoms consisted of circular necrotic spots, with diameter ranging between 10 and 70 mm, well defined by a brown margin, and generally the centre of the necrosis was bleached. Severely infected leaves became chlorotic and abscised. Infected plants rarely died, but the presence of lesions on mature plants decreased their aesthetic quality. The disease started from basal leaves on plants grown in shade and at higher relative humidity, progressing up and outward on the plants, until they were almost completely defoliated. A fungus was consistently isolated from the margin of the necrotic lesions. Based on morphological characteristics, sequence analysis of the rDNA internal transcribed spacer region and pathogenicity tests, the fungus was identified as B. exigua var. linicola. The presence of different species of Phoma (P. exigua, P. nepeticola and P. strasseri) has been reported on Salvia officinalis as well as on other plants belonging to the Lamiaceae in Poland. This is thought to be the first report of B. exigua var. linicola on S. greggii in Italy and worldwide. Isolates of B. exigua have been obtained from over 200 genera of plants and this report expands the list with a new host.