A dynamic mechanistic model for Diaporthe ampelina for improving IPM in Montenegrin and Italian viticulture: VITISUST Project

Phomopsis cane and leaf spot disease (PCLS) is one of the most important grapevine diseases in Montenegro and is re-emerging in other European areas, including Italy. It occurs every year and causes considerable damage. Recently, a bilateral project for ‘Italy-Montenegro Joint Science And Technology Cooperation’ in the area Agriculture and Food Sciences was settled up in order to develop and calibrate a new model for PCLS management. The VITISUST Project is supported by Foreing Affaris Ministries of both Countries. In 2018, studies about overwintering structures of the pathogen were carried out in continuation of previous studies conducted in 2016 and 2017, then a weather-driven model has been developed for predicting Diaporthe ampelina infection. The model is based on a mechanistic approach: the model splits the life cycle of D. ampelina into different state variables and changes from one state to the following depend on environmental conditions by means of mathematical equations. In 2019 and 2020 model evaluation was performed in Italy and Montenegro in specific experimental fields. The disease assessment was performed on typical varieties Barbera and Vranac in Italy and Montenegro, respectively, both trained at double guyot by mean of a visual assessment at dormant stage (i.e. presence and type of symptoms on canes) and during the growing season (i.e. symptoms appearance on leaves and shoots). First symptoms were observed 22 and 19 days after bud break in Montenegro and Italy, respectively, and the final disease incidence was 54.3 % and 50.5 % of the shoots, respectively. The highest disease severity was observed on shoots in the basal and apical sector of the winter cane (curved down) while the shoots developed from the buds located on the top of the cane curve were not affected. This could be explained with the stem-flow effect caused by rainfall that floods pycnidia at the top cane positions and spread the pycnidiospores. After further validation, confirming the effectiveness of the PCLS model, it will be implemented in the decision support system vite.net®, which is currently used by hundreds of growers across Europe for managing other relevant grape diseases.