#16 Western Canada – August 15, 2007
In this issue:
(click the bookmark links below to move to specific sections of this report)
More canola crop closer to maturity
Recent moisture may assist ripening and curing
Early frost may have damaged some canola crops
Aster yellows disease found in many fields
Late season diseases showing up
Insect pressures ease
Adjust spraying thresholds for two pests at once
Scout for prematurely ripening plants
Allow for adequate pre-harvest intervals
Assess seed colour change before swathing
Consider pre-harvest weed control
Thinking about straight cutting?
Reduce risk of wind blown swaths
Keep malathion far away from canola bins
Keep stored canola cool
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
Crop development ranges widely depending largely on the seeding date. Swathing ranges from mostly complete in central and eastern Manitoba to a week to 10 days away from starting in parts of west-central Alberta and the Peace, except for many Polish (B. rapa) crops which have been swathed in the Peace. Combining of canola continued in central and eastern Manitoba as well as southern areas of Saskatchewan and Alberta.
Most regions received some moisture and a return to cooler temperatures last week, with rainfall amounts ranging from a trace to over 50 mm. The moisture will help to fill out the pods on crops still standing and will help to cure crops already swathed. Isolated but in some cases severe hail was reported in many areas, with some of the worst reports from around Dauphin MB, near Canora and Kamsack SK and near Wetaskiwin AB.
An overview of prairie vegetation conditions is available at (use the “start the prairies application” button on the left hand side): http://www26.statcan.ca/ccap/ccaphome_en.jsp
The latest crop report from Manitoba Agriculture, Food & Rural Initiatives is available at: http://web2.gov.mb.ca/agriculture/mwcr/index.php
The latest crop report from Saskatchewan Agriculture, Food & Rural Revitalization is available at:
http://www.agr.gov.sk.ca/docs/reports/crop_report/crprpt070812.asp
Recent moisture from scattered showers in most regions was welcome but has likely come too late or in insufficient amounts to have a big impact on yield. However, it may aid seed development in later maturing fields and will certainly improve conditions for ripening in fields that are nearly ready to swath or curing in those fields already swathed. For current maps of moisture conditions from PFRA for western Canada, check the following links for precipitation since September 1 and April 1 respectively:
http://www.agr.gc.ca/pfra/drought/prpay07_e.htm
http://www.agr.gc.ca/pfra/drought/prpgs07_e.htm
Additional moisture information for Alberta is available from Alberta Environment at: http://www3.gov.ab.ca/env/water/WS/data/precipmaps/weekly.pdf
Frost was reported this past week in parts of the Peace region including St. Isadore, Tangent and Fairview and in north-central Alberta near Two Hills. Although the frost damage was light in many of these areas, some low lying areas likely experienced more damage. Growers need to be patient to accurately determine the level of damage after a frost. To determine when to swath frost damaged canola, check the extent of damage 2-3 days after the frost.
The condition of the frost affected areas will likely fall into one of three main categories, with appropriate swathing strategies for each category. Carefully assess each field and note which scenario the majority of the plants fall into.
Scenario 1: when there is little evidence of frost damage. The pods remain mostly green or tan-green, with few, if any, white spots on the outside of the pods. The seeds inside are mostly intact. Check the colour of the inside of the seeds as well. If the outside of the seeds are starting to turn, the insides should be yellow or a light lime-green. If seeds are still green on the outside and the inside of the seeds are still watery, the outside seed coats should remain intact and turgid. In these cases, leave the crop to mature until enough seed colour change occurs.
Scenario 2: when there are only white specks on the outside of the pods, or only a few seeds in immature pods that are not intact, or only a few seeds in the upper plant parts are prematurely browning. Premature browning occurs when the outside of the seed has been damaged by the frost and the inside of the seed remains dark green. Check the following link for a photo of moderate crop damage, including premature browning of seed vs. normal seed:
http://www.canola-council.org/production/Frost/frost.html
In these cases, the fields should be left and monitored on a daily basis to evaluate further crop changes. If no further damage is evident, the remaining crop may continue to fill and mature. If the seeds continue to deteriorate and/or pod integrity declines, begin swathing to conserve seed volume.
Scenario 3: when there is considerable whitening of the outside of the pods for a majority of the plants. Check the previous link for a photo of severe crop damage. In this case, the pods will begin to shrink and desiccate rapidly, and swathing should begin immediately using the dew to reduce pod shelling and pod drop to conserve any seeds in those pods. In all cases, monitoring should be done daily or every other day to evaluate further crop development and conditions, especially if warmer temperatures and sunshine return.
For more information on assessing frost damaged canola refer to the following link: http://www.canola-council.org/PDF/sept20_canola_fact_sheet_r3.pdf
Unusually large numbers of aster yellows-affected plants continue to be reported in many areas of Manitoba, Saskatchewan and northeastern Alberta. This disease is sometimes mistaken for sulphur deficiencies or herbicide damage. Aster yellows is caused by a phytoplasma, a plant pathogenic micro-organism. The phytoplasma inhabits the phloem (nutrient-carrying vessels) of infected plants and is carried from plant to plant by sap-sucking leafhoppers. Infected plants are more conspicuous because they tend to stand taller and are discoloured compared to non-infected plants. Although highly visible, aster yellows is not usually present on a large enough percentage of plants to cause economic losses. There are no preventative or control measures that producers can do to manage or prevent aster yellows in canola. Following is the link to SAF’s factsheet on aster yellows: http://www.agr.gov.sk.ca/docs/production/asteryellows01.asp
Reports of late season diseases continue to come in, including high levels of sclerotinia in untreated fields in parts of Manitoba, northern Saskatchewan, central Alberta and the BC Peace; clubroot around Edmonton, Leduc and St. Albert; alternaria in northwestern SK and north central Alberta; and fusarium wilt and blackleg in south central Manitoba. Fields that received earlier hail damage appear to be more prone to secondary disease development.
For more information on later season insects and their control, refer to last week’s Canola Watch report at: http://www.canola-council.org/canola_watch_report_2007_15.html
Insect pressures have decreased in most areas this past week. Lygus bugs continue to be found in parts of southern Alberta between Calgary and Brooks and in north-central Alberta near Boyle. Bertha armyworms remain a concern in parts of northwestern Manitoba, in Saskatchewan near Watson, Wadena, Norquay and Preeceville and in areas northeast of Calgary. Diamondback larvae continue to be reported in many parts of central Alberta. Both bertha armyworms and diamondback moth larvae have been found in many fields. With both pests present in some fields, it is important to differentiate diamondback moth larvae from bertha armyworms especially when trying to determine if thresholds are being reached. A couple of tips for distinguishing between the two are:
- Diamondback moth larvae will hang from “threads” when disturbed in the canola where bertha armyworms will not.
- Diamondback larvae will wriggle backwards vigorously if tapped on the head while bertha armyworms will tend to curl up. Don’t forget to try both ends if you can’t tell the head from the tail!
As well, an infrequent insect, the salt marsh caterpillar has been reported in many areas of central and northern Saskatchewan, central Alberta as well as the Peace region. Being an infrequent pest, there are no current thresholds developed. In the absence of further information, growers should consider using similar thresholds as bertha armyworm since the larvae are similar in size and feeding patterns. For more information on salt marsh caterpillar refer to the attached pdf file which was obtained from the University of New Jersey at http://www.cook.rutgers.edu/.
Adjust your thresholds when many pests are present. Feeding damage by more than one insect pest at the same time can create more stress on plants. While neither pest may trigger an economic threshold on its own, the combined damage could be reducing yields faster. In this case, remember to adjust your economic thresholds to account for the increased damage. A good “rule of thumb” for adjusting thresholds when two pests are present in significant populations is to reduce the threshold for each pest by 25%.
During fall scouting for proper swath timing and late insect scouting, producers should watch for abnormal areas that have wilted or for prematurely ripening plants within canola stands that are otherwise healthy. Post swathing (within approximately 3 days after swathing) is another ideal time for disease scouting. Prematurely ripening areas may be indicators of these diseases that restrict water and nutrient uptake by plants. It is important to accurately identify what is causing the damage and properly document the information for future reference and decision making. Identification of clubroot will allow growers to take steps to limit soil (and associated spore) movement to other fields through equipment sanitation. Fields with alternaria will be poor candidates for delayed swathing and should not be straight combined as pods will be prone to shattering.
Before considering any further applications of fungicides or insecticides, allow for the required pre-harvest interval for any products being considered. Remember that pre-harvest interval refers to the time from when the product is applied to when the crop is cut (straight cut or swathed). Growers need to ensure that the appropriate pre-harvest interval is followed to eliminate chances of excess residues appearing in the harvested seed, and damaging markets. Refer to the following links for information on pre-harvest intervals for some common pesticides and description of the importance of following pre-harvest intervals: http://www.canola-council.org/pre_harvest.html
With more crops nearing maturity, growers need to ensure that seed colour change is occurring when assessing the proper time to swath. The colour of mature plants and pods will vary among varieties as they mature. Some will appear ripe on the outside before the seeds are mature, so avoid using plant colour as a gauge to proper timing. Open up pods on the main stem and look at the colour of the seeds to accurately assess swathing timing.
Recent research indicates that the optimum stage to swath for both yield and quality is up to 60% seed colour change. This enables many growers to start swathing at 30% to 40% seed colour change without sacrificing significant yield or quality. It widens the "swathing days" window for all growers, including those with large canola acreages. When conditions are hot and dry, avoid swathing during the hottest part of the day. Swath during cool evening hours, at night or early in the morning to allow plants to dry down at a slower rate. This reduces the chance of green seed. This strategy will also help in situations where hail damage or diseases such as alternaria black spot have predisposed the plants to shattering. Growers may need to consider swathing earlier in these situations as well, but should try to wait for at least 20 to 25% seed colour change if possible. 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.canola-council.org/pub_swathing.html
With swathing and harvest of other crops approaching, consider a valuable weed control tool to set up for next year's canola crop--pre-harvest glyphosate. It's the most consistent and effective treatment 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. Keep in mind that generally the use of pre-harvest glyphosate on crops grown for seed should be avoided.
There are more growers considering straight cutting their canola this year. To be successful, consider the following factors:
Crop Canopy – the crop should be well knitted and slightly lodged to reduce the chance of pod shelling and pod drop. Remember that pod integrity (including petiole strength which influences pod drop) can be affected by frost and drought.
Disease – the crop should be relatively free from diseases including blackleg, fusarium wilt, sclerotinia and alternaria. These diseases can cause premature ripening, which can in turn cause pod shattering.
Hail - Crops affected by hail are poor candidates for straight cutting due to the probability of greater disease infection through damaged tissue and reduced pod integrity from physical damage. Also, any late season hail often causes greater levels of damage to standing crops than swathed crops.
Growers who have decided to straight combine some of their canola may also be considering pre-harvest weed control or desiccation. 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 will be even more critical not to apply the product too early. Apply when the crop has 30% or less seed moisture content. At this stage, the pods are green to yellow and most seeds have turned from green to yellow or brown. 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 applying any pre-harvest chemicals prior to harvest with ground rig sprayers, the use of 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 further reduce losses. 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 60 to 75% of seed has turned brown.
There were reports of wind blown swaths in areas of eastern Manitoba. Many of the worst affected fields were swathed at right angles to prevailing winds. Growers with fields remaining to be swathed are highly encouraged to swath their fields parallel to the prevailing winds to reduce the risk of wind blown swaths and resulting crop loss from shelling. Cut as high as possible (just below the lowest pods) and consider using a swath roller to help anchor the swath into the stubble.
At this time of the year, as growers prepare their bins for storage of the upcoming harvest, it is important to note that oilseed crops including canola can absorb malathion from bin surfaces and the resulting residues have been found in crop delivered to elevators. Therefore, DO NOT use malathion to treat bins destined to store canola from the upcoming harvest. Refer to the following link for further information: http://www.canola-council.org/pesticide_link2.html
For those growers combining canola during warm temperatures, canola storage can also be a concern even at seed moisture levels of 8% or lower. 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. For more information on safe storage and conditioning canola, check the following link: http://www.canola-council.org/media_aug2306.html
Direct questions regarding this report to John Mayko, Senior Agronomy Specialist, Parkland West (West Central AB), with the Canola Council of Canada at maykoj@canola-council.org ph/fax: 780-764-2593.
Direct specific questions regarding regional issues to one of the following Canola Council of Canada agronomy specialists or provincial oilseed specialists:
Derwyn Hammond, Agronomy Specialist, Manitoba, hammondd@canola-council.org, 204-729-9011
Arvel Lawson, Manitoba Agriculture, Food & Rural Initiatives, Arvel.Lawson@gov.mb.ca, 204-745-0340
David Vanthuyne, Agronomy Specialist, Eastern Saskatchewan, vanthuyd@canola-council.org, 306-946-3588
Jim Bessel, Senior Agronomy Specialist, North-central/eastern Saskatchewan, besselj@canola-council.org, 306-373-6771
Penny Pearse/Scott Hartley, Saskatchewan Agriculture, Food & Rural Revitalization, ppearse@agr.gov.sk.ca / shartley@agr.gov.sk.ca , 306-787-4671 / 306-787-4669
Doug Moisey, Agronomy Specialist, Parkland East (East Central AB & NW SK), moiseyd@canola-council.org, 780-645-3624
Matthew Stanford, Agronomy Specialist, Chinook (Southern AB & SW SK), stanfordm@canola-council.org, 403-758-6660
Anne Vos, Acting Agronomy Specialist, Peace Region, av@summit-ag.com, 780-835-4632
Murray Hartman, Alberta Agriculture, Food & 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; Manitoba Canola Growers Association; Agricore United; Saskatchewan Wheat Pool; United Farmers of Alberta; Saskatchewan Agriculture, Food & Rural Revitalization; Saskatchewan Canola Growers Association; Saskatchewan Canola Development Commission; Alberta Agriculture, Food & Rural Development; Alberta Canola Producers Commission; BC Ministry of Agriculture; Food & Fisheries; and the Canola Council of Canada.