1. MILDEW DISEASES OF GRAPES
Pat Nolan
County Plant Pathologist
Dept. of Agriculture, Weights & Measures
County of San Diego

3. Diseases Caused by Fungi and Fungus-like Organisms

4. Downy Mildew Caused By Plasmopara viticola
P. Nolan

5. P. Nolan

6. P. Nolan

7. P. Nolan

10. Source: UC Pest Management Guidelines

11. Powdery Mildew Caused By Erysiphe (formerly Uncinula) necator
P.Nolan

15. P. Nolan

17. Source: UC Pest Management Guidelines

18. Downy versus Powdery Downy Mildew Powdery Mildew Kingdom Chromista
Needs a film of water, high humidity to infect
Opt. for disease 64-75º F
Disease cycle: 5-18 days
Spore types: Sporangia on sporangiophores, Oospores, zoospores
Move by wind or water
Overwinters in dead shoots & leaves
Kingdom Fungi
Needs 65% humidity, no free water to infect
70-86ºF
Dis. cycle: about 5 days
Conidia on conidiophores, ascospores
Move by wind
Overwinters in dormant, living buds