Prepared by Anastasia Kubinec, MAFRI Oilseed Specialist & Pam deRocquigny, MAFRI Cereal Specialist
With the cool, damp weather, crops are not maturing as fast as we would like. ‘Stagey’ crops, big weeds (ragweed, buckwheat, kochia, redroot pigweed) and risks of weathering impacting quality have resulted in many calls about the differences/benefits of swathing, desiccating or letting the crop be.
First, go look at the crop again – how many stages is the crop at? Is it just low spots that have not turned? If the crop is starting to even up, you may want to leave it with the warmer temperatures coming this week (August 12-19, 2013) and let nature work for you. If the crop is at multiple stages and there are big weeds that will cause combine plugging, swathing, desiccating or pre-harvest weed control is a good management option. For specific product information, contact the marketing companies for rates and registration details.
- Swathing or desiccating earlier than recommend (30% seed moisture) will not shorten the maturity of the seed. That is based on genetics and weather. Performing these activities too early will result in reduced seed yield and quality.
- Glyphosate is not a desiccant- it is a pre-harvest herbicide and kills crops and weeds. Use it for perennial weed control and not to desiccate the crop. Don’t use if crop is for seed use.
- Some product MRLs (Maximum Residue Limits) have not been set or are lower than what we can meet for crop export into other countries. Be aware of marketing restrictions that may arise from using certain desiccants/harvest management tools. For pulses see www.rayglen.com/pdf/2013%20Desiccant%20Guidelines%20for%20Growers.pdf. For other crops, talk to you buyers.
- Know the weather conditions at application timing that will give the best results – Reglone works better on senescing plants and when temperatures are warm, Glyphosate works better on actively growing plants.
Field pea –Swath when most of the vines/pods are yellow-tan color and you can only barely leave a thumbnail impression. Desiccate when bottom 75% of pods are yellow with seeds firm and rattling in pods. Desiccation usually eliminates the need for swathing and avoids the issues of wind-blown or rain-soaked swaths, and pick-up losses. Decision to swath or desiccate will be based on weather forecast for the next 10 days, experience and machinery available.
Winter/Spring Wheat – Swathing timing and desiccation timing is the same – seed at 30% to 35% moisture, or hard dough stage (thumbnail imprint can barely be left in seed). Reglone and HEAT are not registered on any cereal crops for pre-harvest use. If crop is intended for seed, using glyphosate is not an option, so swath. If not for seed and the weather forecast calls for wet conditions for the 10 days, glyphosate may be preferred versus swathing as the crop will weather better standing than in a swath.
Barley/Oat – Check with your buyer about their policy on desiccants on the crop. This may make the decision for you. After determining this, the timing of swathing/desiccant is the same as wheat and the considerations to swath or desiccate are applicable as well.
For malting barley, maltsters want plump, mature kernels. The crop must not be swathed on the green side. Delay swathing until the heads have lost their green colour and have a moisture content of <30%. Swath around green patches to avoid having the sample from the field turned down because of green or immature kernels. Keep in mind that wet weather may loosen the hull, reducing quality. Straight combining is becoming popular. Standing malt barley suffers less damage from moisture and dries faster. However, this benefit must be balanced against the increased risk of shattering losses. Six-row barley is more prone to shattering and neck-break than two-row barley.