Pesticide Application and Equipment in Greenhouses
Pesticide Spray Coverage
Adequate amounts of pesticide being sprayed on the target is only one aspect of efficient pesticide application. An equally important aspect is how efficiently and uniformly the target is covered. The term used to describe this is “spray coverage.” The goal in spraying fungicides and insecticides should be landing as many droplets on the target as possible (maximum coverage). This is one reason why nozzles producing fine to medium droplets are preferred in general, especially when using air-assisted sprayers.
Water Sensitive Cards
The most practical and easy way to determine the location and uniformity of pesticide application is to use water-sensitive papers attached to leaves in different locations of the canopy (depth, height). These water-sensitive papers (WSP) should also be affixed to the upper side and underside of leaves (Figure 30.15). Check the coverage on these cards after spraying pesticides. Spray droplets intercepted by the yellow water-sensitive cards leave a blue stain, representing the spray deposit and coverage.
Image Processing Software for Analysis of Droplets
Image processing software is becoming the standard in analyzing the deposition of spray on WSP. This requires a camera or scanner to produce a digital image of the WSP and specialized analytical software to extract the relevant data. DepositScan, offered by USDA, consists of a set of custom plugins that are used by an image-processing program to produce a number of measurements useful for expressing spray deposit distribution.
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