Loading Events

« All Events

  • This event has passed.

El Dorado Wine Grape Growers Powdery Mildew Prevention & Control

May 15, 2019 @ 6:00 pm - 9:00 pm

Please join us for a discussion on Powdery Mildew prevention and control with guest speaker Justin Guadagnolo of Mid Valley Ag Services.

Mildew is one of the most imperative and costly diseases that winegrape growers encounter. At the May 15 meeting, Justin will discuss this disease and focus on the importance of prevention to avoid or minimize the battle of controlling it once established. The cost for labor and materials needed to control the disease is significant to small and large growers alike.

However, the biggest issue may be the potential for a crop to be rejected by a winery due to powdery mildew’s negative impact on grape flavor and wine quality. (Such a clause is often inserted into grape contracts.) This disease is equally detrimental to organic and traditional vineyards and requires a well-thought out and systematic program to keep it out.

Justin will discuss this and touch upon the many factors used to help determine the optimal timing of a fungicide application. These factors include: the powdery mildew index (PMI); a vineyard’s mildew history; temperature and humidity; and, the important factor of what visual symptoms you may spot despite how the PMI reads.

Knowing when to properly time a fungicide application is key to keeping a vineyard clean and in the best condition possible. The most effective application time is often before you see visual symptoms. In addition, the accurate calibration of spray equipment for proper vine coverage is critical to keeping powdery mildew away.

Meeting of the Members
6:00 Wine social and sign-in: Bring a glass and a bottle of wine to share if you’d like
6:30 Announcements: Welcome and general announcements
7:00 Featured Speaker: Justin J. Guadagnolo PCA, CCA, QAL of Mid Valley Ag Services, Inc.
 Board of Directors Meeting follows the presentation. All members are welcome to attend.

About Justin Guadagnolo: Justin is a licensed pest control advisor (PCA), holds a qualified applicator license (QAL) and is a  certified crop advisor (CCA). He has over ten years of experience working in vineyards throughout the Sierra Nevada Foothills and works with vineyards as far south as Tuolumne and as far north as Grass Valley. Mid Valley Agricultural Services, Inc. is a full service chemical and fertilizer retailer with multiple locations throughout the Central Valley of California. They are comprised of administration, operations, sales and technical service departments.

Please join us and bring your specific questions, concerns and observations for Justin. We hope to see you there!


El Dorado Wine Grape Growers Association


Veteran’s Hall
130 Placerville Dr.
Placerville, CA 95667 United States
+ Google Map
(530) 621-5892