"Swathing canola at the proper seed colour change will reduce green seeds and ensure high grades and prices," stresses David Vanthuyne, Canola Council of Canada agronomist for Eastern Saskatchewan.

The best time to swath for optimum canola seed yield and quality is when average seed colour change on the main stem is at 50 to 60%. At this stage, seeds will have changed colour on at least the bottom half of the main stem in B. napus varieties and on the middle and upper pods in B. rapa. When seeds in the bottom half of the plant have changed colour, seeds in the top, or last formed pods will be firm and roll between the fingertips.

To be considered "colour changed," green seeds must have small patches of colour or spotting. Seeds slowly turn from green to light yellow, or reddish-brown to brown, depending on the weather and variety, he says.

Canola seeds within pods on the main stem will change colour about 10% every two to three days. Physiologically mature seeds lose moisture at about 1 to 3% per day. Start inspecting canola fields approximately 10 to 14 days after flowering ends. The end of flowering is defined as the stage when less than 5% of plants have flowers.

"After assessing the main stem, look at seeds from pods on the side branches to ensure they are firm with no translucency, especially in fields with low plant populations and multiple branches," says Vanthuyne.
Sampling various parts of the field every two to three days and averaging the percent seed colour change will give growers an accurate assessment of the overall maturity of the crop. Plant densities, soil type, topography and moisture availability will affect the rate of seed maturity. "Walk out and sample at least five to 10 plants in various areas of the field," he says.
Growers with large acreages will need to start swathing at about 20% seed colour change. This allows the majority of the crop to be swathed at or near optimum seed colour change. Risk of an early fall frost may also warrant swathing earlier.
"Growers have invested a lot of time and money in their canola crops.
Swathing at the optimum seed colour change will help maximize canola returns," says Vanthuyne.
For a free copy of the Canola Council's Time of Swathing Guide, contact admin@canola-counil.org or (204) 982-2100. An on-line version is available at: http://www.canola-council.org/cpc/timeofswathing.html

This press release is part of the Canola Council's Canola Advantage program. The program is supported regionally by: Alberta Canola Producers Commission; Saskatchewan Canola Development Commission; Manitoba Canola Growers Association; Canola Council of Canada; Peace River Agriculture Development Fund; and B.C. Ministry of Agriculture, Food and Fisheries.