Submitted to: Ohio Fruit and Vegetable Growers Congress
Publication Type: Proceedings
Publication Acceptance Date: 2/7/2001
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: The popular conception among vegetable producers is that high pressure atomization will provide the best canopy penetration and coverage. However, small droplets produced by these nozzles often lack sufficient energy to deposit deep in a canopy and are susceptible to wind movement. The objective of this research was to assess spray deposit characteristics produced by conventional and air-assisted spray delivery systems and to evaluate their impact on tomato disease management. Deposit quantity and quality on tomato leaves was evaluated using imaging technology and colorimetry techniques. Protectant fungicides were applied on a calendar schedule. Differences in spray deposit characteristics between drift reduction, flat fan, and hollow cone nozzles were relatively small. Higher application rates produced higher leaf surface spray coverage. Air-assisted spray delivery produced significantly higher spray coverage on all leaf surfaces than the conventional broadcast sprayer treatments. This machine also deposited more tracer within the canopies. Spray carrier treated with copper ions did not change the performance of either the air-assisted sprayer or a hollow cone treatment. There were no significant differences in foliar infection observed in treatments made with either full or half-rate applications of chlorothalonil. No significant differences in the yield of marketable fruit between treatments were measured. While these experiments demonstrate how growers can improve placement of and use of pesticides, additional work is needed to better define the influence of spray delivery and deposition on the effectiveness of pest management and crop production materials.