Impact of temperature on vegetative and pathogenic development of the fungal multi-host pathogen Lasiodiplodia theobromae (Pat.) Griffon & Maubl.

Lasiodiplodia theobromae is an economically important multi-host plant pathogen infecting nearly 500 hosts, including perennial crops. In Peru, L. theobromae has been identified as the cause of dieback in blueberries, avocados, mangoes, and table grapes. These crops are grown in the northern coastal regions of Peru at temperatures expected to increase due to global warming. We used the aggressive isolate LA-SOL5 of L. theobromae originally isolated from grapevine to study temperature dependence of in vitro vegetative growth, conidiation, conidial germination and virulence on grapevine cultivar Red Globe. Mycelial growth and formation of pycnidia were optimal at 30°C, but pre-infection rates of conidiation and conidial germination increased up to 35°C and correlated well with virulence on grapevine. Our studies show that simple conidiation and conidial germination assays could thus be used to predict development of disease severity and suggest increased severity of L. theobromae -associated dieback in grapes at future climate changes.