Submitted to: Plant Protection Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/18/1999
Publication Date: N/A
Citation: Interpretive Summary: This manuscript is intended to provide educators, growers and research scientists with the latest information regarding the most efficient application techniques for protecting vegetable crops against disease. Basics of good applications, such as calibration, proper nozzle selection and nozzle placement, are critical to ensure effective application of pesticides. However, in the case of many diseases and new fungicide formulations, more emphasis must be placed on methods for increasing spray coverage. Chemical labels provide little guidance for pesticide applicators and most chemical evaluation research programs do not use commercial practices for making applications. New technology, as well as existing equipment can be used to increase on-target placement of pesticides. Results of recent tomato sprayer research demonstrates the potential benefits on new nozzle technology and air- assist sprayer technology. New, low-drift nozzles can improve upper surface spray coverage compared to traditional broadcast nozzles used to protect tomatoes. However, only an air-assist sprayer produced significant underleaf spray coverage. Disease control was significantly better for all application treatments compared to the no-spray control. These results demonstrate that new technologies, such as low-drift nozzles and air-assist sprayers, may improve tomato production and reduce the environmental impact of pest management practices.
Technical Abstract: Proper application of pesticides is crucial to ensuring their effectiveness. Application needs vary depending on the pesticide, crop and the pest problem. The little application research that has been conducted in vegetable crops has been shown that matching equipment to the crop canopy and pesticide and air- assisted applications can improve pest management. Previous field research has provided evidence that spray coverage may be important in providing effective disease control. To evaluate this theory, several different application techniques were used to apply protective fungicides in processing tomato plots. Volume median droplet size for the various nozzles varied from 120-275 microns. An air-assist treatment was also used in the trial. Foliar disease ratings were made three times during the season. Naturally occurring Septoria blight and early blight were observed in the test plots. There were no significant differences in the foliar disease ratings between treatments. Foliar spray coverage measurements were made using a fluorescent tracer. Upperside leaf surface coverage in the top of the canopy varied from 50 - 75%. Only the air-assist sprayer was able to provide any significant underleaf coverage. Growers could find that the larger droplet and air-assist application may provide Septoria and early blight control equal to conventional applications while reducing off- target spray drift.