Colletotrichum cliviicola as a new causal agent causing leaf spot disease on Tilia tomentosa moench (silver linden) in China

Abstract

Tilia tomentosa Moench (silver linden) is a globally preferred option for landscaping and street tree planting. Its intentional introduction to China in recent years has led to widespread cultivation. In 2021, a leaf spot disease significantly impacted silver linden trees in a sentinel garden in China, with an average incidence and disease severity of 94.3% and 5.0, respectively, adversely affecting the trees' growth and development. In this investigation, potential fungal pathogens were isolated from the affected leaves, and Koch's postulate was subsequently employed to validate the pathogenicity of the fungal isolates (TM-1 and TM-2). The pathogen was unequivocally identified as Colletotrichum cliviicola through a combination of morphological observation and a multi-locus analysis (ITS, ACT, ApMat, CAL, CHS-1, GAPDH, and TUB2). This marks the first record of C. cliviicola affecting silver linden in China. The information provided a valuable foundation for the rapid detection and effective prevention and control of the diseases affecting linden trees.