Sprayer Technology

COVERAGE IS KEY
Considerations when Spraying Specialty Crops

With all the different specialty crops, nozzle choices, application methods and agrichemical products, there is no "best-way" to spray. However, by understanding the basic principles of spraying, you can make informed decisions about how best to protect your crop.

The objective of spraying is to deliver an effective, uniform dose of product to the target area in a safe and timely manner. In order to cover your target, you must first think about what your target actually is. Crops can be leafy, waxy, hairy, dense, vertical, and any number of shapes and sizes throughout the growing season. Insects can hide under leaves and while some might move through droplets, others can't and have to be "hit". Diseases require a more complete and uniform coverage and might located be closer to the root, the foliage or on the fruiting body. In short, every application is different.

Start by consulting the "Rules of Thumb" below and think about what you hope to achieve

Water Volume

More	Less
Better canopy penetration Better coverage (to a point) More runoff	Fewer refills Less runoff

Droplet Size

Coarser	Finer
Better canopy penetration Less drift Poorer coverage (at lower volumes)	Worse canopy penetration Better coverage More drift

Forward Speed

Faster	Slower
Done faster Poorer penetration and coverage	Takes longer Better penetration and coverage

Here's an example using a conventional crop:
Cabbage is waxy with tightly layered leaves. In early growth stages, you'll need less water per hectare than later in the season, because there is less plant to spray. You'll want smaller droplets for uniform coverage, because waxy leaves cause big droplets to run and pool. If you use finer droplets, you'll want to improve their poor penetration by slowing down when you spray. You might even consider air-assist and/or an angled spray to convey the droplets under leaves. Since fine droplets drift, so you might want to employ drift-reducing nozzles and shrouds. So, does it make sense to spray carrots the same way as cabbage? Of course not.

There is very little information about spraying specialty crops and still less about doing it in Ontario. The best approach is to take lessons from crops with similar morphology and similar pests and make systematic adjustments based on the efficacy of the application. For more immediate feedback, try placing pieces of water-sensitive paper (available from most nozzle retailers) in and around your crop and see if the droplets are going where you intend them to.

If there isn't a representative conventional crop to learn from, take the time to think about what you hope to achieve and follow the rules of thumb. For more information about the basics of spraying, consult OMAFRA's webpage or consult Jason Deveau, OMAFRA Application Technology Specialist at 519-426-8934 or by email at jason.deveau@ontario.ca.

AIRBLAST 101

Ontario's airblast sprayer operators regularly apply pesticides to ensure the health and marketability of their tree fruit, nursery, berry and vine crops. Their success relies on three things: an understanding of safe pesticide handling, criteria for what and when to spray, and having the requisite skill to apply pesticides effectively and efficiently. Until recently, operators had few if any resources to address the final point.

Airblast 101 is a four hour classroom-based course designed to provide participants with practical tools to allow them to apply pesticides, plant growth modifiers and foliar nutrients in an effective, economic and environmentally-responsible manner. Developed by the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) and funded by Croplife Canada, this course was created to introduce a new operator to spraying, or to refresh a seasoned veteran.

Since its introduction in 2011, hundreds of operators have received a solid grounding in the basics of airblast sprayer operation, as well advanced techniques. Those that have made changes to their spray programs report significant improvement in the effectiveness of the application (i.e. improved crop quality and/or yield) and greater application efficiency (e.g. pesticide inputs reduced by ~10% or more per annum and reduced environmental impact such as drift and runoff).

Thanks to the continuing financial support of Croplife Canada, Airblast 101 is live at www.sprayers101.com and www.sprayers101.ca. The website hosts all the content in the participant's handbook, but also includes a library of additional resources such as:

factsheets,
a series of sprayer-related PowerPoint presentations,
instructional videos, and
articles submitted by extension and university staff across North America.

The website will serve as a one-stop shop for airblast sprayer information and provide information about where Airblast 101 courses are being taught. The website is free to anyone interested in improving their spray programs.