Pay attention to pre-harvest intervals. These intervals — the time between spraying and cutting or straight combining — are important because we don’t want pesticide residues on export canola. For example, lygus bug numbers are high on some early-seeded crops in the Peace and some of these crops are a week from swathing. The shortest pre-harvest interval is 7 days. (See the table below.) Note that if pods are hard and leathery, they are beyond lygus damage at that point anyway. For more on pre-harvest intervals, listen to Denise Maurice, CCC vice president of Crop Production, speaking on ACPC radio. Or click your province to for a link to your guide to crop protection: AlbertaSaskatchewan Manitoba
Keep scouting. Lygus bugs, diamondback moth larvae and bertha armyworms can do a lot of damage fairly quickly. Some good-looking fields in north central Alberta, for example, are at or near thresholds for lygus. Click here to see threshold tables for key insects.
Don’t rush to swath. With many regions one to 3 weeks later than normal, growers may be tempted to swath earlier than optimal. Swathing at 60% seed colour change on the main stem is generally the best time for both yield and quality. If growers can’t wait that long, at a minimum make sure green seeds are firm when rolled between the thumb and forefinger. Swathing prior to 15% to 20% seed colour change will likely reduce yield potential and could contribute to green seed issues under hot and/or dry conditions. For more on swathing timing,click here to see a CCC video.
Growers needed for combine loss study. As part of a CCC-funded project, researchers are looking for growers in select regions to take part in a combine-loss survey. Growers remain anonymous and researchers do most of the work. Growers around Lacombe and Edmonton,click here for more information. Growers around Saskatoon, click here. And growers around Winnipeg, click here.
Growers who seeded clubroot-resistant hybrids should know that low-level infection — up to 8% of plants — is normal for these hybrids. These off-types will be scattered uniformly through the stand.
If resistant hybrids have levels higher than this, a patch of susceptible volunteers is the most likely reason. Volunteer canola densities can easily exceed 10 plants per square foot in canola-on-canola rotations, and will be part of the current crop unless a different herbicide-tolerant system was used. With canola-wheat-canola rotations, volunteer canola in the next canola crop may persist at levels of about one plant per square foot in certain situations.
If volunteers cannot explain high infection rates in resistant varieties, then growers should contact their seed rep for further diagnosis.