How to Harvest Damaged Crop

Sclerotinia stem rot

• In fields with low sclerotinia stem rot infection, growers should swath when healthy plants are at the proper seed colour change in order to maximize yield and quality. Swathing earlier will not stop the disease and will not help save diseased plants.
• If most of the crop is infected, then swath to limit shelling of pods that are diseased but contain healthy seed. These pods will provide most of the crop’s yield.
• When swath-rolling diseased canola, do it lightly to avoid excessive shattering of ripe pods. Sclerotinia can also spread throughout the swath, especially if windrows are packed tight. Since rolling knits the windrow together, protecting plants from blowing in the wind, a light rolling to tuck swath edges into the stubble is usually better than no rolling at all.

Hail

• Hail tends to damage top pods worse than bottom pods. But top pods are at later stages and typically have lower yield potential, so there’s no sense cutting early to save these pods, especially if seeds in these pods are still watery. Concentrate on doing what’s best for the lower pods that are not damaged — which is swathing at 50% to 60% seed colour change.
• An exception: Growers may want to swath early after a really late hail storm. If pods are bruised and seeds in these pods are still firm, then swathing right away may save these top seeds from shelling out. And if these top seeds are firm, seeds lower in the plant should be more advanced and suitable for swathing.

Frost

• Some growers will cut canola in anticipation of frost. Note that this only works when the swath has 3 good drying days before frost hits. In that time, seed has time to dry to below 20% moisture. When seed is less than 20% moisture, enzyme activity that removes green from seed is complete. If light frost occurs before 3 good drying days, green levels can be reduced if there’s enough time before the next frost and if there’s adequate rain to rehydrate the seed. For an explanation how frost stops synthesis of chlorophyll in the seed, read the CCC factsheet "Understanding the maturing canola seed and the impact of frost."
• When canola is fairly green and frost risk is only slight, there is more upside to leaving the crop standing. Swathing too early to avoid the risk of frost can often translate into yield and quality losses.
• With frost, no situation is alike. On the last page of our CCC factsheet "Early Fall Frost. Now what?" we provide 4 frost scenarios with suitable harvest steps for each.

Source: Canola Council of Canada