When Should You Swath (Canola, Wheat, Peas, Barley)?


Research shows that the optimum stage to swath canola is when you have up to 60% seed colour change (SCC) showing on the main stem.  By delaying swathing on any variety to the 60% SCC can improve yield and quality through increased seed size, reduced green seed and higher oil content.  This also will help avoid economic shattering losses prior to or during swathing.  Farmers with large acres of canola should wait till at least 20 to 30% SCC to swath their first field so that their last fields will still be within the optimum swathing stage at the time of finishing.


Ideal time to swath wheat is at the medium to hard dough stage and still firmly attached.  Moisture testing of the entire seed head of 35 – 50% is a useful indicator of when to swath.  Crop is ready to harvest when seed is at the medium to hard dough stage.  Swath when 75% of the seed heads have matured, and if seed heads shatter when roughly struck against the palm.  Harvest immediately if seed heads shatter when gently struck against palm.  Hard spring wheat can be swathed at 45% seed moisture content and still make a No. 1 grade with no bushel loss.  To identify 45% seed moisture content, it should be mid-dough stage where it can be easily crushed between finger and thumb.  The below pictures may also assist in identifying the seed moisture content.  Growers should always use their own judgement and experience to make harvesting decisions.

If a glyphosate is being used as a pre-harvest dry down application, timing is essential.  Properly timed pre-harvest glyphosate application can mean the difference between No. 1 HRS and feed in a wet, humid fall.  Poorly timed application can result in no dry down effect and yield loss from shrunken kernels.  The registered timing for pre-harvest glyphosate is 30% seed moisture content, but there has been a push towards spraying earlier to speed up dry-down.   Glyphosate on wheat with seed moisture content +25% saw improvement on both seed and foliage drying compared to leaving a standing crop.  Maximum benefit of glyphosate was observed when seed moisture content was +40%.  However, this was well before the crops reached physiological maturity and consequently yield losses and high residue levels in the harvested seed resulted.  When seed moisture content dropped below 40%, there was little to no difference in yield losses, kernel weight, test weight, grain protein or germination.  Before doing a pre-harvest dry down application, the amount of green leaf area remaining on the flag and penultimate leaf needs to be observed.  If the top two leaves have died from disease or other stresses, then a pre-harvest glyphosate application will not work and only leave you disappointed.  The glyphosate must translocate to the roots to stop growth, and if there is dead tissue between the stem and green leaf area the glyphosate has nowhere to go but to accumulate in the leaf and will not stop growth.


Field pea desiccation can speed up dry down when crop maturity is uneven, or when green weed growth is a problem. A desiccant will not assist in maturing immature seed. Field pea desiccation can eliminate the need for swathing, avoiding potential problems with wind-blown swaths, rain-soaked swaths, and pick-up losses.

These tips will help you desiccate your field peas properly:

  • Apply desiccant as the field pea crop is approaching physiological maturity: bottom and mid-area pods have turned tan to yellow color, and top pods are pitted and starting to turn yellow.
  • Apply the desiccant at the same time as the proper swathing stage, wait approximately five to seven days, then straight combine, or swath and follow immediately with the combine,
  • Spray only as many acres at one time as can be combined in two or three days after dry down.
  • Use proper rates and high water volume, and spray at the correct crop stage

Swathing can be done when most of the vines and pods have turned to a yellow-tan color, and seeds are difficult to dent with a thumbnail. As much as one-third of the vines and pods may still have some lime green color left, but these plants will cure in the swath. The fully formed but immature seeds will dry without much shrinking; the overall seed moisture content will be approximately 25%.


Feed barley can be swathed 5 to 10 days before it can be harvested by straight combining. Swathing reduces losses from insects, from shattering, from hail and frost, and eliminates problems associated with harvesting grain with green undergrowth and green kernels. Barley may be swathed without loss of yield or volume weight as soon as most of the crop has turned from green to light brown or buff color, and the kernels contain less than 40% moisture. Grain intended for seed should contain less than 35% moisture before being swathed.

Kernel moisture should be determined with a reliable moisture meter on representative grain samples from the entire field. Kernels that contain about 40% moisture are in the firm dough stage. They can be flattened by squeezing between the thumb and forefinger, but no beads of moisture will appear in the squashed dough.

At swathing time, some small patches of less mature, slightly green barley will usually be present, but this should also be cut. Some varieties of barley develop a slightly purple or pink color as they mature and ripen for swathing.