Preliminary evaluation of foliar diseases effect on grapevine growth

During the last few years the evaluation of economical injury level has represented a very important step in the rationalisation of crop protection management. Treatment applications can be timed according to the relationships between the real damage (i. e. reduction of potential yield) and the cost of intervention (economic threshold of application). On these basis a reduction of pesticide distribution, as well as an increase of their efficacy can be obtained. To reach these goals the functional consequences and the disease impact on crop physiology must be investigated, as well as their global consequences on crop growth. The present study was realised to evaluate the effect of downy mildew (Plasmopara viticola Berl. et De Toni) and powdery mildew (Uncinula necator Burr.) attacks on grapevine (Vitis vinifera L.). During the vegetative season and in correspondence with the development of pathogen infections, healthy and diseased leaves were collected to assess the consequences of fungus attack and intensity on several growth parameters. During the same period the number of leaves of the main and lateral shoots, the number of lateral shoots, the number of clusters, the diseases attack were measured every fifteen days on 20 healthy and infected shoots. Collected data were statistically analysed and the obtained results were discussed to emphasise direct and indirect damages due to pathogen attacks, with the physiological and technical consequences.