By Mitchell Japp, MSc, PAg, Provincial Specialist, Cereal Crops; Matthew Bernard, MSc, PAg, Provincial Specialist, Oilseeds; Dale Risula, MSc, PAg, Provincial Specialist, Special Crops
Two potential challenges in using a swather in 2019 arise from the early dry conditions experienced. In some fields, or parts of fields, the crop stand may be too thin to support the swath on the stubble. Even if the crop emergence was reasonable, the crop may be too short to lay a swath successfully.
#selltheswather has been a popular phrase for a long time. Generally, a swather has remained on most farms for canola harvest management, but with straight-cut (pod shatter-tolerant) varieties being available in recent years, some farms may indeed have sold the swather.
Straight cutting can remove the extra step and extra cost that swathing can incur at harvest. Additionally, in some conditions, the crop can be more at risk (to wind, pests, wet/disease conditions, etc.) while drying in a windrow. If the swaths are combined too soon after swathing, there might not be enough time for green seed to clear in the windrow. However, a swather is a useful tool for managing variable staging. Assuming no pre-harvest herbicide application has been made, and the pre-harvest interval has been exceeded for pesticide applications, there are no MRL concerns with using a swather.
In canola, optimum swath timing is 60 per cent seed colour change on the main stem. For larger operations or flexibility in harvest management, swathing can begin at 30 to 40 per cent seed colour change on the main stem without losing much yield or quality. Swathing, if possible, might be the best option for fields with extreme maturity variability, since it avoids risk of early herbicide application shutting down maturation of delayed plants, avoids risk of accumulating residues of systemic herbicide and is compatible with canola regardless of shatter-tolerance rating. Avoid swathing in hot weather (30 C and above) when possible, since conditions could create a very rapid natural desiccation resulting in higher green seed, as well as lower oil content. Many crops this year are shorter than in a year with less extreme weather. When possible, aim to cut just below the pods to maximize the stubble height for anchoring the swath and snow catch to help replenish moisture in the spring. Swathed canola will be ready to combine at 10 per cent moisture, which will be about five to 14 days after cutting (depending on size of swath, bunching in swaths or weather).
Flax is ready to swath at 75 per cent brown boll stage. Make sure your sickle bars/knives are sharp, because flax straw fibre is naturally very tough, more so than most other crops. In hot and dry weather, be ready to combine even a couple of days after swathing. Swathed flax is ready to combine once grain moisture reaches 10 per cent or less, corresponding with 90 to 100 per cent brown boll stage (the seeds will rattle loudly within bolls). Swathing flax is ideal for crops with non-uniform maturity.
Although mustard is relatively shatter-resistant, swathing can be effective in fields with different stages of maturity. Swathing should begin at 25 per cent seed moisture; lower pods will begin to change colour and upper pods will be green. Check seed colour change, as well; swath timing should correspond with 75 per cent seed colour change from green to yellow (in oriental and yellow), and 60 per cent from green to brownish/red (in brown mustard). Target nine per cent seed moisture for combining.
Peas are ready to swath when the bottom 30 per cent of pods are ripe, the middle 40 per cent of pods and vines are yellow-coloured, and the upper 30 per cent of pods are turning yellow. This is the same stage to either desiccate or swath regarding either method of choice. If you harvest too soon, immature seeds will be harvested and cause downgrading. Waiting too long will result in excess shattering and will also expose peas to weathering degradation.
Lentils may be swathed, desiccated or treated with pre harvest herbicide when the bottom third of the pods turn yellow to brown and rattle when shaken. Swathing can hasten dry down and reduce shattering. Cut the lentils close to the ground, setting the cutter bar at an angle of 20 to 30 degrees. Pick-up reels and vine lifters are usually used to do a good job.
In some years, it would be feasible to cut above the later tillers. This may lead to straw management issues, but at least the primary yield and best quality has been collected separately from the later immature kernels. In 2019, the crop height is less than normal and this is likely not feasible.
When a true desiccant is being applied to oilseeds (except for canola with pod shatter-tolerance), be aware there is increased risk of pod/boll shatter or pod/boll drop if there is too much delay between desiccant application and harvest.
If harvesting a pod shatter-tolerant canola, allowing it to dry down naturally and allowing the delayed patches to catch up will be the most suitable and economical option. But timing for straight cutting canola depends on a few things. Focusing on seed moisture and harvesting earlier minimizes crop exposure to less ideal weather later in the season, but will pass more green material through the combine and could result in higher amounts of unthreshed losses. Allowing more time for dry down will enable a more efficient harvest but delays harvest more and increases risk of shattering. The quickest straight cut harvest approach will result from allowing complete dry down but will significantly delay harvest timing and might require a pre-harvest aid. Targeting 10 per cent or lower seed moisture is ideal.
Flax is ready to straight cut when grain moisture reaches 10 per cent or below, or 90 to 100 per cent brown bolls. If flax is harvested last or after most other crops have been combined, ensure your cutter bars/knives are sharp. The naturally tough nature of the flax straw fibre will be particularly challenging to combine with dull knives. The time and cost required to swap out sections need to be weighed against slower ground speed, stops and repair time associated with dull knives. Lastly, a stripper header can be a good option for flax, especially when the stems have not fully dried down but the bolls are ready for harvest.
Mustard, especially yellow, is relatively shatter-tolerant and straight cutting is a good option in fields with even maturity, or in crops that are too short to achieve adequate stubble height for anchoring the swath. But, be aware that straight cutting fields too early that have a range of maturity could result in higher levels of green seed. Aim for nine per cent seed moisture to harvest mustard. If following cereal harvest, remember to adjust the concave and fan speed settings to minimize unthreshed or cracked seed; check SaskMustard's production manual for details.
For patches of delayed maturity, your harvest approach will depend to some degree on guessing what weather will be encountered at harvest. For example, in extreme hot and dry conditions at harvest, seeds in delayed patches might not fully fill and could shrivel up. In this case they could be considered a loss, but therefore your harvest timing decisions do not need to consider those later patches. In less extreme years, the seed from plants in those delayed patches might still fill and would be economically worth saving, and thus your harvest approach will have to acknowledge these parts of the field.