#17 Western Canada – August 22, 2007
In this issue:
(click the bookmark links below to move to specific sections of this report)
Crop maturity slowed by cooler weather
Frost may have damaged some canola crops
Assessing frost damage
Late season diseases showing up
Insect pressures vary
Adjust spraying thresholds for multiple pests at once
Allow for adequate pre-harvest intervals
Scout for prematurely ripening plants
Assess seed colour change before swathing
Swathing timing with uneven growth
Swathing early to avoid frost?
Consider pre-harvest weed control
Desiccation tips
Assess crop conditions prior to considering straight cutting
Straight cutting tips
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 continues to range widely depending largely on seeding date and area. Cool, wet weather over the past week limited the rate of crop advancement across many areas. Swathing ranges from virtually 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 continued in central and eastern Manitoba as well as southern areas of Saskatchewan and Alberta.
Most regions received some moisture and a continuation of cooler temperatures last week, with rainfall amounts ranging from a trace to over 165 mm. The moisture will help fill out pods on crops still standing and will help cure crops already swathed. Isolated, but in some cases severe hail was reported in some areas including Grenfell, Odessa, Admiral, Leader and Imperial, SK as well as Viking and Woking, 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/crprpt070818.asp
For current maps of moisture conditions from PFRA, 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 at Insinger, Leroy and Porcupine Plain, SK as well as in parts of western Manitoba. Although the frost damage was light in many areas, some low lying areas likely experienced more damage, especially at Porcupine Plain, which had frost on two consecutive nights.
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 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 falls into.
Scenario 1: 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 are mostly intact. Check the colour of the inside of the seeds as well. If the outsides 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 insides 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: There are only white specks on the outside of the pods; only a few seeds in immature pods 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: There is considerable whitening of the outside of the pods on most 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 seeds. 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
Reports of late season diseases continue, including: high levels of sclerotinia in untreated fields in parts of Manitoba, northern Saskatchewan, central Alberta and the B.C. Peace; aster yellows across all areas; clubroot around Edmonton, Leduc and St. Albert, AB; alternaria in northwestern SK and north central AB; and fusarium wilt and blackleg in south central MB. Fields that received hail damage appear to be more prone to secondary disease development. Although there is nothing that can be done at this point in the season, records of disease incidence can assist in rotation and other management decisions for next year.
Insects reported this week include:
Bertha armyworms remain a concern in parts of western Manitoba and across many areas of Saskatchewan.
Diamondback larvae continue to be reported in many parts of SK as well as parts of south central Alberta including Rumsey and Torrington.
Flea beetles have been reported in parts of southern MB, southern and western SK and southern AB. Crops still left standing in these regions should be closely watched as flea beetle pressure is likely to increase as the remaining fields (food sources) are swathed.
Cabbage seedpod weevil numbers (second generation) are increasing in southern AB. Again, fields left standing are at most risk and should be monitored closely and frequently.
For more information on later season insects and their control, refer to a previous week’s Canola Watch report at: http://www.canola-council.org/canola_watch_report_2007_15.html
Adjust 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 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%.
Before considering any further applications of pesticides, allow for the required pre-harvest interval for any products being considered. Remember that pre-harvest interval refers to the time from application to when the crop is cut (straight cut or swathed). Ensure 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 a description of the importance of following pre-harvest intervals: http://www.canola-council.org/pre_harvest.html
During fall scouting for proper swath timing and late insect scouting, 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 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. 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.
The hot and dry weather earlier this summer has caused purpling and premature plant colour change in many canola fields. This is a relatively normal response to stress and growers need to ensure that seed colour change is occurring when they assess the proper time to swath. The colour of mature plants and pods will vary among varieties. 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 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. 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.
When assessing seed colour, also check seed firmness. Under cool conditions, seeds near the top of the plant may continue to fill and become firm before the lower seeds begin to turn colour. Also, be conscious of disease-infected or hail-damaged fields and do not let the premature ripening of the diseased or damaged plants influence the time of swathing. Realize that the bulk of the yield is likely still coming from the healthy plants. A better strategy than swathing early to capture more yield is to swath during dew periods to prevent shattering of the damaged plants. To learn more about proper field assessment, refer to the revised Canola Council publication "Canola Time of Swathing Guide" or visit the Canola Council website: http://www.canola-council.org/pub_swathing.html
There continue to be many questions regarding swathing timing for canola fields with variable growth caused by uneven emergence or stress from early season flooding. Growers should assess where the majority of their yield will come from and manage accordingly. If the majority of the field is still green, swathing should start when adequate seed colour change occurs in these areas. In fields where green and mature areas are more equal in size, be sure that seeds in the green areas are firm and no longer translucent. Delay swathing as long as possible to allow for seed colour change to start in the green areas. To minimize losses in the ripe areas, consider swathing in the evening or early morning.
Growers considering early swathing in anticipation of frost to avoid or reduce green seed levels need to remember that swathing prior to 15-20% seed colour change will likely reduce some yield potential. Also, canola has to dry down sufficiently to reduce freezing damage and it may need to be swathed for several days before this stage is reached, especially if conditions are cool and damp.
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.
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 60-75% of seed has turned brown.
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.
Straight cutting has been successfully done with all types of headers, but most consistent success has come from the use of flex headers or rigid headers with extensions such as the Biso header attachment. Draper headers can work well also, but take care with the transition areas from the drapers to the feeder house, as gaps in these areas can allow for seed loss to occur. With any headers, adjust the reel as far back as possible, so that any seed shattered by the reel has a chance of being recovered by the table below. Adjust reel speed to match ground speed and keep the reel as high as possible to reduce the chances of shattering seed. Combine as soon as crop condition will allow. This will reduce the time the crop is prone to damage in the field. As a result the crop may be tough or damp, especially if no preharvest glyphosate or desiccant was used. This will likely require more threshing power as well as increase the moisture content of the seed. Ensure that adequate aeration or drying facilities are available to condition the crop properly for storage.
There were more reports of wind blown swaths this week. Many of the worst affected fields were swathed at right angles to prevailing winds. Growers with fields still to swath are encouraged to swath their fields parallel to 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 bins for storage, 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.