Swath, Desiccate or Let it Be – Field Peas & Cereals?!?

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.

Key Notes:

  1.  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.
  2. 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.
  3. 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.
  4. 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.


Have a follow-up question?

Assessing Canola for Swathing Timing? Why Not Look for Diseases Too!

Prepared by Anasatsia Kubinec, MAFRI Oilseed Crop Specialist

Once your canola comes out of flower the countdown is on to swathing and then harvest. 

The prime stage to be swathing is at 50-60% seed color change.  On the plants that looks like the bottom 1/3 of the plants pods have mostly black/brown seeds, the middle 1/3 has 50% brown/black seeds and the top 1/3 seeds are firm when rolled between your fingers and at there are some seeds that can be found to have spots started turning brown.

While out there staging for swathing, scout for the diseases your canola field has too.  Scouting at this stage does not mean control, but it will give you and idea of diseases the crop has and how you can plan for your next canola crop in that field.

Examine the plants from root to top.  What do you see:

Leaves – yellowing and lesions – could be blackleg, look also for black pepper spots that could be blackleg (raised black spots that don’t rub off or smear).  No black spots – it could be alternaria which will also have concentric rings in the lesion.  Just yellow but lesion look ‘water-soaked’, that may be the start of sclerotinia

Stems – grey/white lesions – does the spot ‘shred’ when you scratch the lesion, then is is probably sclerotinia.  Does the lesion have black pepper spots and does not shred – then it is probably blackleg. Is there entire portion of the stem that are grey and hollow, but not shredding or no black spots?  Then is may be grey stem. 

Base of plant – see pinching?  It could be a root rot.  If you cut through the base of the stem and see blackening in the base that is blackleg.

Get what you see confirmed by your agronomist or take the plants to your local MAFRI office to be confirmed.  Then write the diagnosis down.  Management options like longer time between canola crops, variety selection and fungicide use can be integrated into your future cropping plans and reduce the amount, and severity of the above diseases in the future.

For more information also see Canola Council of Canada CANOLA WATCH for July 31, 2013 http://www.canolawatch.org/

SCLEROTINIA on STEM – note the shredding. Photo from Anastasia Kubinec, MAFRI

BLACKLEG on STEM – see black pycnidia or “pepper spots.” Photo from Anastasia Kubinec, MAFRI

BLACKLEG found when cutting through canola crown.
photo from Anastasia Kubinec, MAFRI


Have a follow-up question?

How do I know when it is time to swath my canola?

First of all, walk or drive around the perimeter of the field to assess for uniformity – no flowers should be seen and plants should not look grass green. Drive around again, stop and go into the crop at numerous points and pull pods from the bottom of the main stem, the middle and the top, as well as pods from secondary stems.  The seeds in the pod on the bottom of the plant should be firm with some black seeds and most seeds with a spot of black or tan color. Seeds in the middle pods should be firm with most seeds also showing a spot of color change.  In the top pods, seeds should be firm and not able to be squished between fingers.  The odd seed may have a spot of color change.  Seeds from pods on side stem should also be firm and have seeds with some color change. If the crop is ripening too fast or the edges are ripe and the middle green, swath the area that is ripe, potentially in the early morning when there is still dew on the pods, as this will reduce the amount of shelling out.

Have a follow-up question?