Petri disease is a grapevine trunk disease responsible for the decline and dying of young vines a few years after planting. Phaeomoniella chlamydospora (Pch) is one of the main Petri disease-causing pathogens in asymptomatic vine plant material. It is believed that Pch remains latent within plant material, but when young vines are subjected to stress, Pch becomes pathogenic, leading to visual symptoms of Petri disease.
Project Layout
Young Merlot vines were used, own-rooted, and grafted on SO4 rootstock in an experiment that spanned two seasons in a greenhouse and four seasons in field conditions. These vines were inoculated with different Pch spore concentrations and subjected to water deficit. Arbuscular mycorrhizal fungi (AM) were also introduced into the greenhouse experimental soils to investigate their effects on disease development. DNA was extracted from grapevine wood, and PCR tests were performed to determine Pch abundance before- and after the experiments.
Results
- In the greenhouse, Pchabundance in inoculated grapevines was greater in water-stressed grapevines treated with AM than in stressed grapevines without AM or in non-stressed grapevines.
- Also, in the greenhouse, necrosis was more severe in vines inoculated with Pch.
- In the field, Pch abundance was not affected by water stress, but vine necrosis was greater in grapevines inoculated with a high spore concentration of the fungus.
- Petri disease-like symptoms developed during the third year of the field experiment, and water stress increased grapevine mortality.
Significance of the study
This study affirms a connection between water stress, Pch abundance and possible mortality of young grapevines within the first few years after planting. The mechanisms are still unclear. Producers must be critically aware of the soil water status in their newly planted blocks. Under- or over-irrigating leads to poor root development and water uptake, inducing stress in young vines that may develop into Petri disease and vine mortality.
Reference:
Hrycan, J., Bowen, P., Forge, T., Hart, M., & Úrbez-Torres, J. R. (2025). Impact of water stress on Phaeomoniella chlamydospora abundance and Petri disease symptom development in young grapevines. OENO One, 59(1). https://doi.org/10.20870/oeno-one.2025.59.1.8317