Fighting Fungal Diseases Organically: Powdery Mildew

Today I am reading an online issue of Wines & Vines and in it there is an article written by Glenn T. McGourty on Fighting Disease Organically. McGourty called for active intervention if the vineyard is to be maintained organically and stressed the following.
Basic Integrated Pest Management (IPM) principles:

• Know the disease lifecycles
• Use canopy management to reduce conditions that favor disease development
• Monitor for disease incidence and severity

In California, Extension Plant Pathologists Doug Gubler and Carla Thomas have developed a Powdery Mildew Risk Assessment Index (RAI). Three consecutive days of temperatures in the optimum growth range for conidial spore development, 70-85°F, triggers the model. There are suggested treatment intervals based on this model which helps to time and stretch the treatment intervals.
Organic Fungicides to Combat Powdery Mildew
Kumulus 80 df is an organically certified micronized sulfur when applied at full bud break is highly effective at stopping powdery mildew infections early in the season.
Materials suitable for low- to moderate-pressure disease conditions include:

• Stylet oil
• Potassium bicarbonate (i.e. Kaligreen, Armicarb)
• Biological fungicides (i.e. Bacillus subtilis (Serenade) and Bacillus pumilus (Sonata))

In addition to the use of the above organically approved fungicdes to combat powdery mildew, cultural practices in the vineyard can help ameliorate the disease.
Canopy Management

• Remove leaves around the clusters after fruitset
• Remove 4 to 6 basal leaves to expose fruit clusters early in the season to help thicken the fruit cuticle, helps to resist mildew infections
• Exposed fruit also has a less humid microclimate, and sunlight is likely to hit the fruit for part of the day, discouraging mildew growth.
• Fungicide applications on exposed fruit are much more effective

This is a very good article which goes on to discuss in detail how to mange botrytis, Phomopsis and eutypa. I'll follow up with more details on those in another blog.