What Did We Learn? A Wrap-Up of the Orchard Sprayer Workshops.

In June and July of this year, the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) held 5 orchard sprayer workshops across the apple-growing regions of Ontario. The purpose of these workshops was to evaluate sprayer performance and recommend ways to improve coverage and spray deposition.

At the workshop, we looked at the spray deposition with different water volumes, air speeds (no air at some sites), travel speeds and cover sprays versus alternate row sprays. We used the spraying practices typically used by the grower on site as the standard. 

These side by side trials were installed before the workshop started using Surround® WP Crop Protectant. Surround WP is a useful visual tool for checking spray deposition. 

What did we find out? At some sites alternate row spraying didn't look too bad, depending on factors such as canopy thickness and porosity. However, at each site it was shown that alternate row spraying was not as consistent as spraying every row. While spraying every row does take extra time and fuel, the probability of getting better coverage is very good. Just think of apple scab. Poor coverage for this disease normally results in poor control. 

From a quick visual assessment, there didn't appear to be any disasters when comparing the different water volumes, air speeds and travel speeds trials. There appeared to be slightly better coverage with a higher water volume. 

Also, using some air helps with droplet distribution and deposition; however, if the air speed is too high, too much spray may be forced through the intended target row setting up two or three rows over. 

Another demonstration was shown using a patternator that was built by John Gardner and other OMAFRA staff, using the design principles developed by Dr. Andrew Landers of Cornell University. 

The sprayer is readied and positioned beside the patternator, roughly the distance it would be from the row during spraying. The patternator takes a sample of the wall of spray delivered by the sprayer at different height intervals all done from a stationary position. A more detailed description was given previously in the June 2007 Orchard Network Newsletter. This is not a quantitative test. It is a tool that shows where the spray is going at different heights. What we were looking at during these workshops was pattern symmetry. 

When using the patternator, if it is shown that disproportionate amounts of water are collected at various heights in the canopy, adjustments to the sprayer should be made. This may involve resizing, turning off certain nozzles or adjusting nozzle angle and/or airflow pattern. Clogged nozzles show up wonderfully well when using the patternator. 

Figure 1 - OMAFRA Specialists Kathryn Carter, Todd Leuty and John Gardner ready the patternator at one of the sites during the recent sprayer workshops held across Ontario.

Information on windbreaks was covered at the workshops. Highlights of this presentation were:

• 1 to 3 rows of trees is optimal for windbreaks
• Plant at least 3 different tree species, such as spruce, pine, white cedar, gray alder, Russian olive (note: Russian olive is not a host for fire blight)
• 50% porosity is ideal (50% is air space; 50% is needles, leaves and branches)
• For an effective spray drift buffer, the windbreak should be about twice the height of the spray release height. A width of 30 to 100 feet, consisting of diverse trees, shrubs, vines and herbaceous plants will effectively catch 50 to 90 percent of drifting spray material. Conifers ensure drift buffers are working early in the spring before other deciduous species have leafed out.

Another point raised was that spray record keeping is becoming increasingly more important. Plan to keep detailed records of your pesticide applications. It is a good idea to include the wind speed at the time of spraying in these records.

A special thank you to Paul Frankis, Murray Porteus, Art Moyer, Charles Stevens and John Ardiel for hosting the sprayer workshops. Also, thanks goes to the sprayer equipment dealers for presenting on nozzle orientation and new sprayer technologies. We appreciate the time and effort all of you put towards these workshops.

Thank you to BASF Canada Inc. and Engage Agro for supplying the Surround WP for the spray demonstrations. We are grateful for the support. Also, thank you to the growers and consultants for attending these workshops. It is encouraging to see Ontario growers continuing their education in pesticide application.