Plasmopara viticola

Common name: Downy mildew of grapes


Plasmopara viticola ia an obligate parasite and the sexual reproduction spores are Oospores (survival spores-decayed leaves in soil). The asexual reproduction spores are called Zoospores. It is a severe fungal disease and the optimum conditions are winter-wet and spring-warm rainy summer. Spread through the wind (conidia) and rain. The pathogen survives in leaf debris (soil) or diseased shoots. Symptoms of downy mildew may be confused with powdery mildew spots, in early stages.

Downy mildew symptoms under the leaf surface . Source: Dr. Dimitrios Tsitsigiannis


Leaves: Oilspots. White cottony fungal growth on the underside of leaf on the oilspots(warm/humid night). Oilspots became necrotic and may proceed to defoliation

Stem: Shoots takes an S form with oil brown areas sometimes covered with white fungal growth

Fruits: Brown discoloration and shrinkage of berries

Flowers: Inflorescences are covered with white fungal growth

Hosts: Vitis vinifera, other vitis varieties

Kingdom Chromista
Class Oomycetes
Order Peronosporales
Family Peronosporaceae
Genus Plasmopara
Species P.viticola

“Diseases of fruit trees and grapevine”- Panagopoulos G.C

Department of Primary Industries and Regional Development’s Agriculture and Food division- Government of Western Australia, Downy Mildew of Grapes