Swath timing for uneven canola fields

July 22, 2015 - Issue 18

Earliest canola in southern Alberta and here and there across the Prairies will be close to swath timing in the next week or two. Many of these early fields are not looking good, with patchy emergence, uneven emergence and short stature due to moisture stress.

The swath timing decision becomes more difficult in crops with plants at multiple stages of growth. For example, if some plants are at 60% seed colour change (SCC) on the main stem and other plants are still flowering, growers may want to hold off on swathing. Or if plants are large with many secondary stems, the main stem may be at 60% SCC, but seeds in side branches are still mushy and green. These seeds would wither up and amount to nothing if the crop is swathed at 60% SCC on the main stem.

Here are some tips to help with the swath decision on these fields:

Check the whole field. If half the plants are ready and half are just beginning seed color change, growers may want to hold off on swathing. By waiting 3 or 4 days, there is minimal risk of frost damage for riper parts of the field and a huge potential benefit for later parts if frost doesn’t occur.

If the field has distinct late and early parts, the two parts could be swathed at different times. When assessing stage for swathing, ignore plants that are prematurely ripened due to diseases like sclerotinia, blackleg and clubroot.  However, determine the actual cause of the premature ripening so appropriate changes can be planned such as selecting resistant varieties in the future.

There is no “perfect” time to swath uneven crops. Choose based on the best time for the majority of plants in the field with the least negative impact possible on the rest.

How many days of swathing does the multi-stage field(s) represent? If these fields represent a week or more of swathing, you may have to get started. If you have better fields with higher yield potential and more consistent staging, deal with optimal timing on those fields first, and leave the 50-50 fields for later.

Canola Watch