Environmental health

A spray buffer zone is the downwind distance separating the point of direct pesticide application from the nearest boundary of a sensitive habitat. Farmers must plan to leave a suitable spray buffer zone between the treatment area and adjacent sensitive areas.

The Pest Management Regulatory Agency (PMRA) of Health Canada has created an online calculator that enables pesticide applicators to modify the size of the spray buffer zone specified on a pesticide product label when spraying their fields.

Using the Site-Specific Buffer Zone Calculator takes only a few moments, and rewards good agricultural practices that reduce the potential for spray drift with a reduced buffer zone. The required spray buffer zone is calculated based on weather conditions and spray equipment used for an individual spray application.

When the pesticide product label allows, use the PMRA calculator to reduce the potential for spray drift and the required buffer zone.

Learn more about spray buffer zones and vegetative filter strips.

As part of sustainable agricultural practices, pesticides need to be used appropriately as part of a larger stewardship program. Farmers are stewards of the land and take steps to minimize the environmental impact of pesticides on soil, water and wildlife. One of these steps is the use of conservation buffers.

Conservation buffers help to maintain soil, water, and air quality by trapping sediment, filtering pesticide and nutrient pollution, as well as minimizing off-target pesticide movement caused by drift, water runoff, and soil erosion.

Syngenta is involved in numerous water quality stewardship initiatives and partners with growers, grower organizations, government agencies, researchers, and non-government organizations. These initiative help to preserve water quality and enhance biodiversity by promoting native habitats in agricultural areas.

These initiative help to preserve water quality and enhance biodiversity by promoting native habitats in agricultural areas.

Spray drift occurs during pesticide applications, when droplets move through the air from a target site to a non-target site. This can expose people, wildlife, and other plants to pesticide residues. However, in order to minimize spray drift, we must first understand what causes it.

The spraying equipment used in the field can have a large impact on spray drift. During applications, pesticide droplets flow through hydraulic nozzles. Each nozzle is classified according to its spray quality, which produces different sized droplets.

Smaller droplets provide better coverage, but tend to evaporate and drift onto non-target areas. Larger, coarse droplets are not easily moved by the wind but are more likely to run off the target area and provide less coverage.

Weather conditions, natural and man-made physical barriers, and the type of target site are additional factors that will influence spray drift.

Research has shown that for most applications, some spray drift is expected. This is not unacceptable, as very small amounts of most pesticides will generally not affect non-target sites. However, great precautions should be taken to minimize drift where highly sensitive sites occupied by humans, non-target crops, and wildlife habitats are known to be close by.

Learn more about drift mitigation .

Under normal, sunny daytime conditions, the atmosphere is considered “unstable”, which means that the air close to the ground is warmer than the air above. In these unstable conditions, increased wind speed causes different air layers to mix together. Any pesticide in the air is quickly dispersed and diluted with clean air.

At night, a “stable” atmosphere occurs, where the air close to the ground is now cooler than the air above it. This is called a temperature inversion. Instead of air layers mixing together, the cold air near the ground is slower, more concentrated, and moves horizontally, rather than upward.

Low wind speeds mean that any pesticides remaining in the air can hang over the treated area in a concentrated cloud for a period of time. If the wind speed increases, that concentrated cloud could drift over another area and cause damage.

Heavy cloud cover and some wind can produce neutral atmospheric stability conditions. A combination of no inversion, good dispersion, and consistent wind direction tends to result in the best spraying conditions.

Pesticide applicators must consider several factors when treating a crop, such as swath displacement, sprayer and nozzle type, equipment calibration, application speed, and protective shields.

During normal application of pesticides, some displacement of each swath may carry pesticide to the adjacent area. Applicators usually allow for this when determining their spray run positions; for example, they may not spray to the edge of the outermost rows by adjusting those swaths. Swath displacement is a normal practice, particularly in aerial application, and can be an effective drift mitigation technique. In orchard spraying, some rows of trees may be skipped when spraying, using a similar type of swath adjustment.

Newer equipment such as tower sprayers, wrap-around sprayers, tunnel sprayers, and hooded sprayers can reduce drift, as can nozzle technology.

Low pressure or low-drift nozzles produce a medium to coarse droplet size spectrum and minimize fine droplets. Products requiring finer droplets are generally applied at a lower speed to improve coverage and reduce drift.

Shields, such as those that cover spray nozzles, allow spraying with ground equipment in higher winds.

Excess spray mixture is diluted pesticide left over in the spray tank after a pesticide application. Excess spray mixture cannot be stored, so it’s always preferable to minimize excess spray mixture through careful measurement, calibration and application. If a pesticide containing spray mixture cannot be used in accordance with label directions, the farmer must evaluate its waste classification before determining the correct disposal method.

New technologies, such as sprayers with in-line pesticide-injection systems, eliminate excess spray mixture entirely. Pesticide and water are kept in separate tanks, and a separate metering pump feeds the pesticide into the spray line. Any excess water is left in the water tank, while excess pesticide remains in the pesticide tank.

Rinsate is pesticide-containing water that results from rinsing a pesticide container, pesticide equipment, or other pesticide-containing materials. Rinsate should not be stored but can be recycled if used the next day as a portion of the next spray mixture of that same chemical.

Farmers rinse application equipment over an impermeable surface that drains to a sewage pump. The site is labeled and located away from aquatic habitats. Rinse water can then be recovered from the sewage pump for recycling.

Canada has an extensive container recycling program that collects obsolete pesticides. The program, called Cleanfarms, is funded by pesticide manufacturers and operates as a not-for-profit industry stewardship organization.

Cleanfarms partners with ag-retailers and municipalities to collect empty commercial pesticide, fertilizer containers, and bags from farmers across the country. Since the program began in 1989, more than 143.6 million empty containers have been collected.

Cleanfarms is also undertaking new initiatives that provide farmers with recycling options for on-farm plastics and packaging, as well as seed bags, to keep these materials out of landfills.

Retailers that would like to return deposit containers and totes can notify Syngenta for container pickup using this form.