Best time for… Tips for various harvest-time scenarios

September 18, 2019 – Issue 25

Best time to spray perennial weeds. If you have a canola field with a lot of perennial weed escapes, especially Canada thistle, are you better to spray them pre-harvest or post-harvest for maximum efficacy? There are benefits to both options. Read more.

Best time for a disease survey. The ideal time is around 60 per cent seed colour change when diseases are at their peak, relatively easy to distinguish and identification is not yet confused by the saprophytic fungi that can set in as plants dry down. Verticillium is one disease that can be more obvious and easier to identify after cutting a canola crop. As the plant dies, verticillium microsclerotia — if present — will start to grow under the stem’s skin. Read more about post harvest scouting tips for verticillium and other diseases. Post harvest is also OK for soil tests to check for clubroot and stubble tests for blackleg pathogens.

Best time for pre-harvest glyphosate. It is critical to wait until seed moisture content is less than 30% in the least-mature areas of the crop before applying glyphosate. Applications made before the correct stage increase the risk of unacceptable residue in the seed. By waiting until 50 to 60% seed colour change in the least-mature areas of the field, growers can be confident seed moisture will be at less than 30%. VIDEO with more tips.

Best time for pre-harvest Reglone. Diquat (Reglone Ion) stops maturity, so anything too green when sprayed will stay green. The risk with an uneven crop is that chlorophyll levels will be locked in, which is why Diquat should not be used on crops with extreme variation in maturity. Diquat application timing is 90% brown seeds. At this stage, all but 10% of the seeds on the very top and outer most branches haven’t completely turned black or brown. This is very different from a seed colour change (SCC) measurement that only refers to the main stem and includes any seeds with a degree of speckling or mottling. Syngenta provides the following tips on how to stage the crop: (1) Survey the field. Look for brown colouring in the upper pods and stems. You should not see any yellow or green. (2) Listen for a rattle in your pods. Mature seeds are loose in the pod and rattle when the plant is shaken. (3) Look for brown seeds. Strip out seeds from several areas of the field. The crop is ready when 90% of each plant has seeds that have turned completely brown. Syngenta supports the use of Reglone Ion on shatter-tolerant canola only.

Best time for pre-harvest Heat LQ. Saflufenacil (Heat LQ) has a labelled application rate of 60-75% brown seed, although most recent BASF literature recommends 80% brown seed. Talk to your rep about the application timing they support.

Best time to swath. Waiting until at least 60% seed colour change on the main stem is the best time for yield, but by mid September the higher priority may be timely harvest. Here are two helpful articles: Swathing early: Economics AND Frost risk rising. Should I cut that green canola?

Best time to straight combine. To determine whether a canola crop is “ready” to straight combine, stalk dry down, pod dry-down, and seed moisture all need to be considered. Read more. Which is most important to you? What are you compromising by focusing on one and not the others? Your answers to these questions will determine the ‘best’ time to combine and the amount of ‘time’ it takes to work through the crop.

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