Canola Watch Report No. 6
Western Canada June 4, 2008
In This Issue
Seeding virtually done
Weekly moisture variable and sporadic
Crops slow to recover from frost
Reseeding
Tips to hasten maturity
Crop emergence
Remain on the lookout for flea beetles
Control weeds early
Spraying tips
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.
Seeding virtually done
Seeding is complete, except in parts of northern Saskatchewan near Prince Albert and in central, eastern and northern areas of the Peace region, which report 75-90% completion.
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Crops slow to recover from frost
Crops are slowly recovering from extensive frosts across most of Manitoba and Saskatchewan. Cool conditions have slowed crop recovery. The amount of frost injury depends on moisture conditions, duration of the frost and the coldest temperature reached, rate at which thawing occurred, the growth stage of the plants, and the amount of cold temperature hardening the plants had experienced. Canola seedlings will usually recover from a light spring frost that does not damage the plant’s growing point. A light frost that wilts the leaves but does not cause any browning will not severely damage the plants. Even plants with some discolouration of the leaves (ranging from yellowing or whitening to brown necrosis or blackening in more severe cases) may survive.
Always wait several days following frost to determine the extent of damage and whether or not the growing point has been killed. If there is any green colour at the growing point in the centre of the frozen leaf rosettes, the plant should recover. In some cases the hypocotyl may be intact and green, indicating life and a good chance of plant recovery. In other cases, the top part of the hypocotyl may be shrunken, constricted and/or brown. It is unlikely these plants will survive.
Remember: A proper assessment of frost damage cannot be made for several days – until it can be determined whether new growth is appearing from damaged plants. Under good growing conditions, green re-growth from the growing point should occur in four to five days. Under poor growing conditions – cold and/or dry, which has happened this year – re-growth may take up to 10 days.
If you have dry soil, rethink reseeding strategies and determine the odds of getting quick germination and adequate emergence of a reseeded crop, especially after the further soil disturbance of reseeding.
For more information on assessing frost-damaged canola, refer to the Canol@Fact "Tips for assessing spring frost damage in canola": http://www.industrymailout.com/Industry/Redirect.aspx?u=109996&q=74799595&lm=11426940&r=95579&qz=d9a62eeb899228607677bfcedc552643
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Reseeding
Some reseeding has taken place in areas of Saskatchewan and Manitoba. Many of these fields were reseeded due to multiple frosts or a combination of frost, flea beetles, wind damage and drought. However, comments indicate that only some of these fields actually required reseeding.
Each year some fields suffer from poor emergence or damage after emergence due to frost, wind, hail, seedling diseases or insects. It is often difficult to decide whether to replant. To help with this decision, carefully 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?
To make a decision, 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. 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 can have a significant impact on the ability of the plant to compensate. As a guide, a reasonable threshold for conventional varieties is 32-43 plants/m² (3-4 plants/ft²) early in the season.
However, 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 will be later in maturity. Crops replanted late in the season typically yield less than earlier plantings that had poor stands.
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Tips to hasten maturity
Late seeders and re-seeders – give your canola the best possible start. The combination of good to excellent soil moisture and favourable soil temperatures is ideal for rapid and even emergence as long as you use proper seeding techniques. Seed shallow to facilitate rapid emergence, ideally at a depth of ½ to ¾ inch. Keep pre-seeding tillage shallow to help maintain seedbed firmness and moisture. Consider increasing seeding rates slightly to reduce individual plant branching. Make sure seeding rates are high enough to establish the target of 7-14 plants/ft². Apply recommended rates of phosphorus fertilizer for the "pop-up effect" in cooler areas to ensure more uniform crop maturity, but watch seed-placed fertilizer rates to avoid seedling toxicity.
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Crop emergence
Crop emergence ranges from patchy and uneven in parts of the eastern prairies to excellent in parts of southern and central Alberta, but crop growth remains slow in all areas due to cool nights and at best, only normal daytime highs. Consequently, many of these fields are at greater risk of yield loss due to weed and/or insect pressure. Assess the relative competitiveness of a canola crop when deciding on control measures and timing.
Begin scouting fields 7-10 days after seeding to detect germination problems early. With ample moisture and warm soil, emergence can begin to take place within a week. Refer to the Canol@Fact "Factors affecting canola survival for seeding to 21 days after emergence": http://www.industrymailout.com/Industry/Redirect.aspx?u=109997&q=74799595&lm=11426940&r=95579&qz=eddce10e4b28693321511d99a8ce0fcd
When scouting fields with stand establishment problems, check for the blue seed coat at or near the root of the seedling or at the depth of seeding. This will indicate affected plants are either from the current year’s seed or are volunteers from previous years.
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Remain on the lookout for flea beetles
Flea beetles continue to appear on cruciferous weeds, volunteer canola and early emerging canola in many parts of Manitoba, eastern Saskatchewan near Moosomin, and in the central Peace region, with some insecticide spraying occurring in all of these regions. Watch continuously for flea beetle activity on the newly emerging crop. Don’t assume that flea beetle activity is low because of cool weather. 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=74799595&lm=11426940&r=95579&qz=8309c19e1ec782b32215c940b71d4f76
Quick Tips for Scouting and Assessing Flea Beetle Damage
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Scout fields daily in the spring, especially in areas with high flea beetle pressure the previous year.
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Assess damage to cotyledons and the first true leaves of seedlings.
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Scout the first 14 days after emergence, especially on sunny, calm days when temperatures exceed 14oC.
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Scouting twice a day may be warranted when weather conditions are ideal for flea beetle feeding.
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Determine the extent and distribution of damage by observing plants at random while walking across the field, checking all field and slough margins where the insects over-winter.
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Damage and flea beetle numbers may be higher at the field edge than further into the field.
Current seed treatment insecticides require flea beetles to feed on the canola in order to provide control, so seeing some flea beetle damage doesn’t mean seed treatment insecticide is not working. These have a limited window of efficacy, and delayed emergence and growth due to cool, wet weather may allow feeding damage to build up.
Canola seedlings can withstand 50% leaf loss. However, flea beetles can locate, attack and quickly injure or destroy seedlings shortly after emergence. Therefore, the action threshold for flea beetle feeding on canola is 25% defoliation with flea beetles present. Check the entire plant for signs of flea beetle feeding. The stem and the underside of leaves may also show signs of feeding, especially under cooler conditions.
Applying controls 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 the field edges, a foliar spray around the field edges may provide sufficient protection. However, on hot and calm days flea beetles are capable of moving longer distances and may cause significant damage further into the field.
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.
Some growers are adding an insecticide for flea beetle control along with one of their herbicide applications. However, before considering this practice, determine whether both the target insects and target weeds are at appropriate levels and growth stages. For a list of approved tank mixes, refer to the following link: http://www.industrymailout.com/Industry/Redirect.aspx?u=109998&q=74799595&lm=11426940&r=95579&qz=631137c02c326919640b23e20de00da3
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Control weeds early
In some areas, the combination of early seeding and the lack of pre-emergent burn-off applications has helped weeds – especially grassy weeds like wild oats – develop faster than the crop. In these cases it is especially important to do an early in-crop herbicide application. Control of early germinating weeds is important to minimize moisture and nutrient loss and reduce weed competition to allow establishment of a healthy and competitive crop stand. However, it is important to give frost-damaged crops time to recover before applying another stress in the form of herbicide. Poor growing conditions often lead to poor weed control as well. Refer to the Canol@Fact http://www.industrymailout.com/Industry/Redirect.aspx?u=109999&q=74799595&lm=11426940&r=95579&qz=75ceba30dfbbbdcbafb0ac6735e5af98 for more information on weed control timing.
Recent frosts have meant a delay of herbicide applications in many areas as growers wait for the crop to recover and begin actively growing again. However the cool, and in some cases dry, conditions have delayed crop recovery, and weed pressure is only adding to the stress on the crop. Therefore, when deciding the appropriate to spray after receiving an environmental stress, take into consideration which factor(s) are causing the most stress on the crop. Weed spraying may be warranted over crop recovery after a frost if weed pressure is high and conditions are dry, since the weeds will be using what little available moisture is present.
Assess the number, growth stage and type of weeds present 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 to ensure good weed control and crop tolerance.
If you are relying on post-seeding, pre-emergent burn-off applications, keep in mind that many areas are reporting canola emergence within a week of seeding. Monitor carefully for emergence prior to spraying to avoid crop damage.
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Spraying tips
Review the following weed control and spraying tips:
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Control weed flushes early to maintain crop yield potential.
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Choose the proper nozzle to apply the product effectively and reduce the chances of damage to neighbouring crops from spray drift.
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Use adequate protection during spraying to reduce personal exposure.
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Water quality is key to achieving proper performance of many herbicides, particularly with glyphosate and many grassy weed products.
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Custom applicators (and growers in general) need to ensure they are applying the right product to the right field. Ensure legal land descriptions and field directions are 100% accurate to eliminate misapplication of products.
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Follow label directions for proper product rates and application techniques. Although good weed control has occasionally been reported in the past using reduced product and/or water volume rates, remember that the performance will be affected by factors such as growth stage and environmental conditions, and unless the product is applied in accordance with label directions the applicator will have little recourse in the event of poor product performance or crop damage.
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Place a 4’X6’ tarp on the ground prior to spraying or simply shut off booms for a few yards to create a weed check. This will allow for performance comparisons.
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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.