Detection of pine needle diseases caused by Dothistroma septosporum, Dothistroma pini and Lecanosticta acicola using different methodologies

Dothistroma and Lecanosticta needle blight are among the most damaging foliage diseases in plantations and natural pine stands worldwide, and are therefore listed as quarantine organisms in numerous countries. The aim of this study was to validate different methodologies used for the detection of both diseases. Based on multiplex quantitative PCR (qPCR), simultaneous detection and discrimination of the three pathogens Dothistroma septosporum, Dothistroma pini and Lecanosticta acicola were possible in symptomatic needles. Additionally, the same set of needles was analysed for the presence of all three pathogens using novel end-point PCR assays followed by enzymatic digestion of PCR products. Results were compared with the qPCR data, and for validation, collected needles were screened morphologically for the presence of typical fruiting bodies and spores. Differences in detection sensitivity were found between the detection tools. The qPCR-based detection allowed for specific and efficient identification and quantification of all three pathogens simultaneously. At the same time, conventional PCR assays, which target the multicopy ITS region, showed increased detection sensitivity and can be conducted without the use of expensive infrastructure and reagents.