Check for seed colour change before you swath canola (July 26, 2005)

The colour of canola seed on the main stem at swathing is a good indication of the quality growers will get in the bin. Canola Council agronomist for eastern Saskatchewan David Vanthuyne says swathing canola when the colour is right will keep yield and quality high and green seed low.


Vanthuyne says the best time to swath is when average seed colour change on the main stem is at 50 to 60%. At this stage, he says, 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,” Vanthuyne says, “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 black, depending on the weather and variety. Canola seeds within pods on the main stem will change colour about 10% every two to three days.


“We’ve opened up the swathing days window to 20 to 60% seed colour change from 20 to 40% seed colour change”, Vanthuyne says. “This basically translates into an additional 10 days of swathing to maximize seed yields and quality.”


The Canola Council agronomist advises growers to start inspecting canola fields approximately 10 to 14 days after flowering ends - 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,” Vanthuyne says.


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. Vanthuyne says it’s a good idea to walk out and sample at least five plants in various areas of the field.


Hot dry, windy weather can also cause rapid seed moisture loss and seed colour change. “We’ve seen seeds on the main stem change from 20% to 50% in just a few days under these conditions,” he cautions.


To catch most of the crop at or near optimum seed colour change, growers with large acreages will need to start swathing at about 20 to 30% seed colour change. Vanthuyne says risk of an early fall frost may also warrant swathing earlier than 20% seed colour change.


“Growers have invested a lot of time and money in their canola crops. Swathing at the optimum seed colour change will definitely 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/properstage.aspx


For more information in your area, contact:


John Mayko, Agronomic Research & Extension Manager, 780-764-2593
Derwyn Hammond, Manitoba, 204-729-9011
Jim Bessel, North Central & North Eastern Saskatchewan, 306-373-6771
David Vanthuyne, Eastern Saskatchewan, 306-782-7799
David Blais, Western Saskatchewan, 306-895-2122
Christine Mardell, Peace, 780-402-3066
Doug Moisey, Central Alberta, 780-645-3624
Matthew Stanford, Southern Alberta, 403 – 758-6660


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.