A lot of canola hit by frost or swathed in the heat is now stuck with high green counts. Every field is different, so there is no one best answer. Here are a few questions to ask and sample scenarios to consider before making the decision to combine now or give the crop more time.
—How long has the crop been down? If canola has been down for three weeks and is at 6% moisture and 6% green, this crop has likely cured as much as it will without a lot of moisture to reactivate the chlorophyll-clearing enzymes. Two to 3 days of continuous showers may be required. One big rain is less effective because it does not keep the pods moistened for the time required to absorb high levels of moisture. Warm weather in conjunction with the moisture also helps. Once daytime highs are cooler than 15 C, the chance of any significant de-greening is reduced even with the required moisture. Warmer weather is currently forecast and it’s still September, so you could leave the crop for a few more days to see what happens. If the crop has only been down a week, it may still have time to cure — but if it’s already at 6% moisture (which is possible) curing may be over without some wet weather.
—If the crop has been down for a week or two and moisture is still at 10%, green counts could continue to fall. Added rains would be a bonus, so patience is encouraged.
—Green locked in by heat vs. frost.
Heat: Green locked in by quick dry down due to excess heat at swathing can be cleared again if seed moisture returns to 20%.
Frost: A killing frost to standing or just-swathed crop will stop the enzyme process in affected seeds, locking in green regardless of subsequent of weather conditions. But if crop lower in the canopy was not hit hard by frost, it may continue to cure naturally and clear the green. Waiting will benefit the seed in these pods. Waiting may also cause seeds in severely damaged pods at the top of plants to shell out. This may reduce overall yield but could increase grade if seeds in top pods have a high green count. Scout closely to identify the extent of frost damage throughout the canopy.
—Killing frost may not be as killing as you think. We’ve had reports this fall of canola fields being at -4 C for a few hours but not showing signs of serious frost damage. Monitor these fields regularly to make sure shattering losses are not excessive. If no shattering, the extra time will benefit chlorophyll reduction.
—How much canola do you have to harvest? If you have one or two fields left, you may be in a better position to wait than someone who still has a week or more of steady combining to do.
—How is your other canola grading? If the rest of your canola is No.1, you may be in a position to negotiate a better deal for a few loads with higher green.
—What is the forecast? Moisture and above average temperatures are going to offer the best chance of further curing for crop that has already been down for quite a while. If a week of warm and dry harvest weather is in the forecast, and the crop needs moisture to restart the enzyme process, then binning the crop now may be the best option. October is around the corner and snow is not the moisture you’re looking for.
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