Canola Watch Report No. 16
Western Canada August 21, 2008
In This Issue
Swathing getting into full swing and a few fields harvested
Lygus bug spraying winding down
Watch for grasshoppers in late maturing fields
Isolated spraying for bertha and diamondback larvae
Revised insect thresholds
Keep records of late season diseases
Deciding when to swath? – Check the seed and avoid the heat
Thinking about straight cutting?
Considering chemical applications to assist crop dry-down?
Applying a pod sealant?
Started harvesting? – Keep canola cool
It’s not to early to think about weed control for next year
Flea beetles showing up in some areas
Questions & Contacts
The Alberta Canola Producers Commission (ACPC) has developed an Alberta focused version of this report. Visit the ACPC website at: http://www.canola.ab.ca and click the Alberta Canola Watch button.
Isolated spraying for bertha and diamondback larvae
Some spraying for bertha armyworm larvae was reported in the Prince Albert area of Saskatchewan, with populations approaching threshold levels in northeastern Saskatchewan as well. When determining the number of larvae per square metre, make the assessment in various parts of the field and be sure to beat the plants together to dislodge all the larvae. Thoroughly inspect the soil surface, including areas beneath leaf litter, to get an accurate count. Check the revised insect threshold link below for more information on appropriate economic thresholds. For further information, go to the bertha armyworm section at the following link: http://www.industrymailout.com/Industry/Redirect.aspx?u=124027&q=84588216&lm=11426940&r=108600&qz=0cf47b7a03e5dcb411f58da022177ac2
In some instances diamondback moth larvae are also being found in fields. Spraying was reported in western Saskatchewan around Wilkie, Rosetown, Kindersley and Lloydminster. For more information on diamondback moths refer to this link: http://www.industrymailout.com/Industry/Redirect.aspx?u=125344&q=84588216&lm=11426940&r=108600&qz=042b938c94445d981f202a4230e0544b.
Keep scouting fields but if considering an insecticide application, keep in mind the pre-harvest intervals for the registered products. With the recent hot weather seed colour change is advancing rapidly so be realistic about the number of days to cutting the crop. Also keep in mind that a general rule of thumb is to decrease insect thresholds by 25% when more than one type of insect is contributing to the same type of feeding damage.
to the top
Deciding when to swath? – Check the seed and avoid the heat
The recent hot weather has caused much of the crop that was approaching the swathing stage to yellow very quickly in terms of pod and stem colour. In this situation, remember that some varieties will show pod colour change prior to seed colour change so growers must still ensure that seed colour change is occurring when assessing the proper time to swath. Do not use plant colour to gauge proper timing as some pods will appear ripe on the outside before the seeds are mature. Open up pods on the main stem and look at the colour of the seeds to accurately assess swathing timing.
Research indicates that the optimum stage to swath for both yield and quality is up to an average of 60% seed colour change (SCC) on the main stem within the field. However, for growers faced with uneven maturity within fields, or a large amount of crop which is now maturing at the same time as a result of the heat, it may not be possible to swath all of the crop in that 50-60% SCC window. In situations where uneven maturity is the problem, the best approach is likely to swath when the most mature plants are at close to 60% SCC, provided that the least mature plants are showing some seed colour change at the base of the main stem and that the seeds in the upper pods (and branches) are dark green and firm. This will minimize yield loss from seed shrinkage and improve the odds that the seed will cure although it will likely take longer and may require some moister conditions. For growers with large acreages to cover, waiting for at least 25 to 30% SCC will capture most of the yield potential because the bulk of the seed will be past physiological maturity and entering the dry down phase.
While growers should always try to avoid swathing during the hottest part of the day to minimize shattering of mature pods and slow dry down of less mature ones, this is particularly important in the situations described above. Slower dry down aids the curing process, which is important for reducing the chance for green seed issues. Swathing in the late evening through early morning hours when moisture levels are higher also helps in situations where hail or insect damage is present, or diseases such as alternaria black spot have predisposed the plants to shattering. If damage from these factors is fairly severe and shattering risk is high, growers may need to consider swathing earlier, but should try to wait for at least 20 to 25% average seed colour change.
As mentioned last week there have been some situations (hail damage, rainfall after a period of drought stress) where canola is re-flowering. Any pods forming from these new flowers are unlikely to produce mature seed prior to fall frost. In most cases they should be ignored when assessing seed colour change for swathing, as they will likely contribute very little to the overall yield of these fields.
To learn more about proper harvest field assessment, refer to the revised Canola Council publication "Canola Time of Swathing Guide" or the following link: http://www.industrymailout.com/Industry/Redirect.aspx?u=124032&q=84588216&lm=11426940&r=108600&qz=f514d4145225758c1d416f5843d47205
Finally, there have been many reports of short crop heights and lodging resulting from the stresses of the season. This means crops will require cutting close to the ground to capture all of the pods on the plants, leaving less stubble to anchor swaths. As such, reducing the odds of wind damage to swaths will be even more critical this year. Swathing parallel to the typical direction of prevailing winds in the area and utilizing a properly adjusted swath roller to anchor swaths will help reduce wind damage.
to the top
Thinking about straight cutting?
There are a number of growers considering straight cutting their canola this year. To improve the odds of success, consider the following four factors:
· Crop canopy – The crop should be well knitted and slightly lodged to reduce potential seed loss through pod drop and shelling. Frost, drought and insect damage all affect pod integrity. A uniform crop with minimal green weed growth is also a huge advantage when straight cutting.
· Disease – The crop should be relatively free from blackleg, fusarium wilt, sclerotinia and alternaria, as these diseases can cause premature ripening, which makes the crop prone to pod shatter.
· Hail - Crops affected by hail are poor candidates for straight cutting because they typically see greater disease infection due to tissue damage. The physical damage also reduces pod integrity. If late season hail is common in your area, keep in mind that hail will cause more damage to a standing crop than a swathed crop.
· Frost risk – Canola seed is at significant risk for fall frost damage until seed moisture drops below 20%. This moisture drop will take much longer in a standing crop, making late maturing crops poor candidates for straight cutting. Canola will be much more vulnerable to yield loss and downgrading from frost damage when standing.
to the top
Considering chemical applications to assist crop dry-down?
Growers who have decided to straight combine some of their canola may be considering pre-harvest weed control or desiccation, particularly in fields with uneven maturity. While these products can hasten dry down of mature plants, they will kill any immature ones. It is also important to understand that these products are not designed to seal the pods against pod shattering, and in some cases may make the crop more vulnerable to shattering if harvest is delayed. Be prepared to harvest as soon as the crop is ready as the more rapid dry down will leave the crop vulnerable to shattering sooner than if it is left to mature on its own. If applying pre-harvest chemicals with ground rig sprayers, using crop dividers can reduce the amount of crop loss due to trampling and shattering. In addition, traveling back and forth in the direction of prevailing crop lean will help reduce losses.
If a Roundup Ready canola variety has been grown, a pre-harvest glyphosate application will assist in some dry down of green weeds and offer perennial weed control but it will not dry down the crop. For other types of canola, it is critical to not apply the product too early. Apply when the crop has 30% or less seed moisture content. At this stage, which is past the typical swathing timing, the pods are green to yellow and most seeds have turned from green to yellow or brown. For a faster acting desiccant like Reglone, it is even more important to delay application to allow seeds to reach physiological maturity. The recommended stage is when an average of 65 to 75% of seed on the whole plant has turned brown. Keep in mind that this will be well past 75% seed colour change on the main stem.
to the top
Applying a pod sealant?
There have been many questions from growers considering straight cutting and wondering about some pod sealant products which are new to the Canadian marketplace. These products are designed to prevent the pods from splitting open during ripening. As with any new agronomic tool where information on its performance under our environmental conditions is limited, it is always a good strategy to start small in order to learn what works best. Part of this learning may involve leaving check strips, and in this case it may be wise to leave both a swathed check and an untreated standing check to compare to straight cutting with a pod sealant. The comparison of yield from the swathed treatments to the untreated straight cut will provide a measure of any shattering losses, and comparing them both to the pod sealant will help assess potential yield benefits where shattering was minimal, and risk reduction where shattering was significant.
Most of the questions regarding these products have focused on application timing. The information provided by the companies suggests that the majority of the pods should be changing colour from green to yellow but the pods should still be pliable enough to fold over without splitting open. However, it will also be important for there to be enough seed colour change within the pods to allow curing and harvesting within the window of protection provided by the product you are using. The best advice is to consult with your company representative on the ideal timing for your fields. One other general tip that applies to these products is to stick with the high water volumes that are recommended by the company. Because these products form a physical coating to seal the pods against splitting open, thorough coverage of all the pods is very important.
to the top
Started harvesting? – Keep canola cool
For those few growers that have started combining canola during the recent warm temperatures remember that canola storage can still be a concern even at seed moisture levels considered dry. This can be compounded by the presence of insects such as grasshoppers and ladybugs in the grain. Be aware that canola binned at high temperatures may be susceptible to heating and spoilage even though it may test dry, particularly if it contains green material such as weed seeds, chaff or insects. Use aeration to bring down the temperature of the binned canola.
to the top
It’s not to early to think about weed control for next year
With swathing and harvest getting underway, consider a valuable weed control tool to set up for next year's canola crop -- pre-harvest glyphosate. The challenging conditions this spring resulted in less than ideal control of perennial and winter annual weeds in some fields so this fall may be an opportune time to control these weeds for next year. Fall is the most consistent and effective timing for many perennial weeds, providing an effective and economical alternative to in-crop applications. In early fall, perennial weeds are moving nutrients down into roots and rhizomes to prepare for winter. This is when they are most vulnerable to herbicide translocation to the roots and better control is possible. Wait three full days (72 hours) after application before cutting to allow thorough translocation of the herbicide to ensure extended long-term weed control. If utilizing this tool to control weeds in canola crops prior to swathing, keep in mind that three days typically translates to about a 10 to 15% increase in seed colour change, so in fields with uniform maturity you should be able to spray at up to 40% seed colour change and still swath prior to 60%. In less uniform fields you may not be able to wait for an average of 60% seed colour change to swath, but try to keep the herbicide application as close to the most appropriate swathing stage for that field to avoid yield loss from premature death of less mature plants. Keep in mind that in general, the use of pre-harvest glyphosate on crops grown for seed should be avoided.
to the top
Flea beetles showing up in some areas
Swathing time is a good time to assess the population of emerging adult flea beetles as these will make up the overwintering population that we may have to deal with next spring. High numbers were reported on headlands of fields in the eastern part of south central Manitoba and in the St. Albert area of central Alberta. If you find high numbers in any fields you are scouting this fall, Agriculture and Agri-Food Canada would like to know as they are hoping to collect some for their research into this canola pest. Please contact Dr. Julie Soroka at:
107 SCIENCE PLACE
SASKATOON, SASKATCHEWAN S7N 0X2
Telephone: (306) 956-7294
Fax: (306) 956-7247
Email: sorokaj@agr.gc.ca
to the top
Questions & Contacts
Direct questions regarding this report to Derwyn Hammond, Agronomy Specialist, Manitoba with the Canola Council of Canada at hammondd@canolacouncil.org, 204-729-9011.
Direct specific questions regarding regional issues to one of the following Canola Council of Canada regional agronomists or provincial oilseed specialists:
Ingrid Kristjanson, Manitoba Agriculture, Food and Rural Initiatives, Ingrid.Kristjanson@gov.mb.ca,
204-746-7504
David Vanthuyne, Agronomy Specialist, Eastern Saskatchewan, vanthuyned@canolacouncil.org,
306-946-3588
Venkata Vakulabharanam, Saskatchewan Agriculture, Venkata.Vakulabharanam@gov.sk.ca
306-787-2594
John Mayko, Senior Agronomy Specialist, Parkland West (West Central AB), maykoj@canolacouncil.org ph/fax: 780-764-2593
Doug Moisey, Agronomy Specialist, Parkland East (East Central AB & NW SK), moiseyd@canolacouncil.org, 780-645-3624
Matthew Stanford, Agronomy Specialist, Chinook (Southern AB & SW SK), stanfordm@canolacouncil.org,
403-327-4832
Erin Brock, Agronomy Specialist, Peace Region, brocke@canolacouncil.org,
780-568-3326
Murray Hartman, Alberta Agriculture and Rural Development, murray.hartman@gov.ab.ca,
403-782-8024
Kerry Clark, BC Ministry of Agriculture and Lands, Kerry.Clark@gov.bc.ca,
250-784-2559
The Canola Watch Report provides just-in-time information on canola production to growers and industry. Contributors to the Canola Agronomy Network are:
Manitoba Agriculture Food and Rural Initiatives; Manitoba Canola Growers Association; United Farmers of Alberta; Viterra; Saskatchewan Ministry of Agriculture; Saskatchewan Canola Growers Association; Saskatchewan Canola Development Commission; Alberta Agriculture and Rural Development; Alberta Canola Producers Commission; BC Ministry of Agriculture and Lands; Agriculture and Agri-Food Canada, and the Canola Council of Canada.