Management of Grape Powdery Mildew with an Intelligent Sprayer and Sulfur

Area of Science:

• Agricultural Science
• Plant Pathology
• Horticultural Engineering

Background:

• Grape powdery mildew (GPM) significantly impacts wine grape production in the Pacific Northwest.
• Effective disease management is crucial for maintaining crop yield and quality.

Purpose of the Study:

• To evaluate the efficacy of the Intelligent Spray System (ISS) for GPM management in wine grapes.
• To determine optimal sulfur concentrations and output volumes for GPM control using the ISS.
• To compare ISS performance with traditional air blast sprayers.

Main Methods:

• The study utilized an air blast sprayer retrofitted with the Intelligent Spray System (ISS), featuring LiDAR and Doppler sensors.
• Various micronized sulfur concentrations and output volumes were tested for GPM control.
• Grape cluster severity and leaf incidence were measured to assess disease levels.

Main Results:

• The ISS at a default rate (62.5 ml/m³) with sulfur (6 g/liter) showed higher GPM severity than other fungicide treatments.
• Using the ISS with locally systemic fungicides at 62.5 ml/m³ resulted in the lowest GPM incidence and severity (11%).
• ISS performance with sulfur matched constant-rate sprayers when ISS rate doubled or sulfur concentration quadrupled.

Conclusions:

• Sufficient GPM control may not be achieved with variable-rate sprayers if pesticide rates are not adjusted, particularly for contact fungicides.
• The ISS, with proper adjustments, can reduce pesticide use, water consumption, and labor by optimizing application.
• Variable-rate technology offers potential for more efficient and sustainable vineyard pest management.