Canola Watch Report No. 7
Western Canada June 12, 2008
In This Issue
Cool weather slows emergence and development
Weekly moisture variable and sporadic
Frost strikes again
Hail hits several areas
Reseeding
Remain on the lookout for flea beetles
Control weeds early
Continue regular scouting
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.
Cool weather slows emergence and development
Crop development varies widely. Some earlier seeded crops are at the 4-6 leaf stage, but crops seeded within the last two weeks have not yet emerged. Plant populations vary widely with generally even stands in southern and central Alberta but patchy emergence and variable stands throughout many parts of eastern Saskatchewan and Manitoba due to the combination of frosts, flea beetles and dry soils. Most areas are also reporting slower plant development due to cloudy and cool conditions in many areas.
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Hail hits several areas
Hail fell in eastern Saskatchewan near Langenburg, Melville and Moosomin and in parts of central Alberta near Wetaskiwin, Camrose, Bawlf, Heisler, Castor and Sangudo. Growers considering reseeding should wait several days until it can be determined whether or not new growth is evident on damaged plants – just as with frost.
Hail damage at this crop stage usually results in leaf stripping rather than plant mortality, as hail stones must damage the growing point directly or break the stem completely to cause plant mortality. However, the damage will delay development as the plant channels its resources into rebuilding damaged parts.
If possible, avoid applying herbicide until signs of recovery are evident to help ensure good crop tolerance and adequate weed control. Canola stands with lower than optimal plant density will require careful management for the remainder of the season. Properly timed weed and insect control will be critical to allow the crop to compensate for plants lost early in the season. The crop likely will take longer to mature.
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Reseeding
More reseeding has taken place in areas of Saskatchewan and Manitoba that experienced multiple frosts or a combination of frost, flea beetle feeding, wind damage and drought.
Each year some fields see poor emergence or damage after emergence due to frost, wind, hail, seedling diseases or insects. The decision to reseed is difficult. To help with this decision, consider the cause and severity of damage, soil moisture, reseeding costs, potential herbicide residues, and the date. Will reseeding likely increase income without significantly increasing risk?
Accurately assess crop injury and estimate yield potential of the surviving stand. Growers often overrate the injury and underestimate the potential for recovery of canola seedlings. Remember that canola seedlings injured by insects, wind or frost need several days of recovery before an accurate survival assessment can be made.
Remember there is no "minimum number of plants" because growing conditions have a significant impact on the ability of the plant to compensate. With herbicide-tolerant systems, late in the season seeding or with dry seedbed conditions, 11-22 plants/m² (1-2 plants/ft²) can be adequate. Thin stands such as these can yield up to 90% of the normal stand seeded at an early date, but they will mature later. Crops replanted late in the season typically yield less than earlier plantings that had less-than-optimal stands.
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Remain on the lookout for flea beetles
Flea beetles continue to appear in many parts of Manitoba, Saskatchewan, in central Alberta around Edmonton, and in the central Peace region. In some cases, growers are including an insecticide along with their first pass of herbicide without doing an adequate job of assessing flea beetle pressure. This can destroy beneficial insects, which can expose crops to damage from other pests later in the growing season.
Ensure insect pressures are at or close to threshold levels before applying recommended insecticides at the proper dose. Watch continuously for flea beetle activity on newly emerging crops. Don’t assume that flea beetle activity is low because of cool and/or rainy weather. A return to warmer weather will increase flea beetle pressure, which may cause more damage because of delayed crop development. Striped flea beetles are known to be more active than crucifer flea beetles under cool conditions. For more information on identifying flea beetles, refer to the following link: http://www.industrymailout.com/Industry/Redirect.aspx?u=103437&q=76292989&lm=11426940&r=97015&qz=a573696f1aee3478451bc8fe81621ae5
Current seed treatment insecticides require flea beetles to feed on canola in order to provide control, so seeing some flea beetle damage does not mean the seed treatment insecticide is not working. However, these treatments have a limited window of efficacy, and delayed emergence and growth due to cool, wet weather may allow for increased feeding damage.
Check the entire plant for signs of flea beetle feeding. The stem and underside of leaves may show signs of feeding, especially under cooler conditions. When flea beetle feeding is combined with poor plant growth and low plant populations, canola can tolerate less feeding than if plants are growing rapidly under better conditions.
Applying control measures at 25% defoliation will reduce the risk of flea beetle damage reaching a level where yield loss and plant development are substantially reduced. If damage only exceeds threshold levels near field edges, a foliar spray around the field edge may provide sufficient protection. However, on hot and calm days flea beetles are capable of moving long distances, which could result in significant damage further into the field.
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Control weeds early
Weed growth has been rapid in most areas due to favourable moisture conditions. Cool, wet weather has delayed herbicide application, which is especially problematic in fields that did not receive a pre-emergent burnoff application. Control of early germinating weeds helps reduce weed competition for moisture, nutrients and light, which allows for establishment of a healthy, competitive crop stand. If weed pressure is low to moderate, give frost-damaged crops time to recover before applying another stress in the form of a herbicide. Herbicides will be more effective if weeds are actively growing. However, spraying may have to take priority over complete crop recovery after frost, especially if weed pressure is high and conditions are dry, since weeds will be using what little available moisture is present.
Refer to the Canol@Fact at http://www.industrymailout.com/Industry/Redirect.aspx?u=109999&q=76292989&lm=11426940&r=97015&qz=ccb9d6c626a748a0beb999c3ac2f951a for more information on weed control timing.
Assess the number, growth stage and type of weeds present, as well as the range of canola plant development prior to herbicide application. Read the herbicide label. With several herbicides available in various formulations (glyphosate, for example), it is important to apply the correct rate of active ingredient at the best timing possible to ensure good weed control and crop tolerance. Don’t wait for all weed flushes to emerge before applying the herbicide. Most crop yield damage is done by weeds that emerge before or at the time of crop emergence. These weeds must be controlled in a timely fashion.
With all products – especially contact herbicides such as Liberty – ensure that recommended water volumes are used to allow adequate coverage, especially for harder to kill weeds such as grasses and in heavy weed pressure situations.
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Continue regular scouting
Scout fields on a regular basis to detect crop development problems early. Consider establishing a scouting tramline by driving an ATV in an ‘X’ or ‘W’ pattern in the field to establish pathways for crop scouting. This will allow for easier scouting with minimal trampling at later crop stages, especially once the crop is blooming.
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Questions & Contacts
Direct questions regarding this report to John Mayko, Senior Agronomy Specialist with the Canola Council of Canada at maykoj@canolacouncil.org ph/fax: 780-764-2593.
Direct specific questions regarding regional issues to one of the following Canola Council of Canada regional agronomists or provincial oilseed specialists:
Derwyn Hammond, Agronomy Specialist, Manitoba, hammondd@canolacouncil.org,
204-729-9011
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
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