Le conseguenze dell’inerbimento sullo sviluppo di peronospora ed oidio della vite

As soil management influence vine growth, it can also affect the outbreaks of downy and powdery mildew. The effect of total cover cropping with legumes or grasses and of traditional tillage has been evaluated from 2013 to 2015 by calculating the average infected area of leaf and bunch on unsprayed vines. It was also evaluated downy mildew natural sporulation and tissues susceptibility by artificial infections on leaf disks. As regards downy mildew, its development in the vineyard was very similar in the different treatments. The number of germinable sporangia had not an uniform trend, resulting in turn higher on each treatments, while artificial infections have been more severe on the leaves of grapevines managed with traditional tillage. As regards powdery mildew, its development in the vineyard was stronger in the tillage treatment in 2014 and 2015. Not all outlined differences were statistically significant (P ≤ 0.05), probably due to the limited number of plants on which it was possible to make observations compared with a large variability between the blocks. Even with these restrictions, the results let suppose that traditional tillage could promote the development of both diseases by increasing the nutritional value of host tissues and the vigor of the vines. The shadowing effect of a thick vegetation might have affected mainly powdery mildew, more exposed to the negative effect of solar radiation because of its development on the outer surface of leaves and clusters