Canola Watch Report No. 5

In this issue:
- Seeding progress
- Soil moisture conditions
- Soil temperatures
- Reseeding
- Maturity considerations
- Broadcast seeding
- Weed growth
- Flea beetles
- Stem feeding
- Cutworms

Canola seeding continued to advance across many areas of central and northern Saskatchewan and central and northern Alberta including the Peace region. However, rain and cool weather this past week stalled seeding progress across most areas of Manitoba and southeastern Saskatchewan. Seeding progress across Manitoba varies from 25 to 90% complete, with the southwest, central and eastern regions generally most advanced. Seeding in Saskatchewan ranges from about 70% seeded in the southeast to virtually complete in the northwest. Most of Alberta, including the Peace are almost done except for about 10-15% remaining in the Innisfail and Beiseker areas and 20% in the LaCrete area. The lack of general precipitation in areas other than the southern Prairies and most of Manitoba this past week has allowed rapid progress of seeding, despite the cool conditions in most areas. Soil moisture conditions across western Canada range from poor to excessive. Growers in many areas of Manitoba and southeastern Saskatchewan are reporting standing water in fields. But moisture conditions continue to deteriorate across many areas of western Saskatchewan and central Alberta from Red Deer north. Rainfall is needed very soon in these areas to allow for adequate crop germination.

For current maps of moisture conditions from PFRA for western Canada, check the following link: http://www.agr.gc.ca/pfra/drought/drprec7_e.htm

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/crprpt040524.asp

Additional moisture information for Alberta is available from Alberta Environment at: http://www3.gov.ab.ca/env/water/WS/data/precipmaps/weekly.pdf

Soil temperatures remained low across most areas this past week. Canola emergence in early seeded fields has been quite general across most regions, but crop development is delayed due to the cool temperatures. The delayed crop development has led to many concerns regarding the efficacy of seed treatments, in terms of the window of protection that can be expected following emergence. As cool weather delays crop development, it puts greater stress on the plants, especially when faced with multiple pressures such as insects, disease and frost. The best advice is to scout fields frequently following emergence for any signs of damage, so that rescue treatments can be applied appropriately. Some reseeding has taken place in areas of northwestern Saskatchewan near Lashburn and St. Walburg, central Alberta near Coronation, Edmonton and Westlock, and the Peace region near Debolt, Rycroft and Falher. Many of these fields were reseeded due to multiple frosts or to a combination of frost, flea beetles and seedling diseases.

Each year there are fields that suffer from poor emergence or damage after emergence due to frost, wind, hail, seedling diseases or insects. The grower often has difficulty deciding whether to replant. To aid in the decision, carefully consider the cause and severity of damage, soil moisture, reseeding costs, potential herbicide residues, and the date. The key question is: will reseeding likely result in greater net income without significantly increasing risk? The first crucial step in the reseeding decision is to accurately assess the crop injury and then estimate the yield potential of the surviving stand. Growers often overrate the injury and thus underestimate the potential of canola seedlings to recover. Canola seedlings injured by insect, 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 to 43 plants/m2 (3 to 4 plants/ft2) early in the seeding season. However, with herbicide-tolerant systems or late in the season seeding or with dry seedbed conditions, 11 to 22 plants/m2 (1 to 2 plants/ft2) can be adequate. Thin stands such as these probably will yield 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 (see Table 1 for more examples).

Table 1: Examples of Reseeding Yields with B. Napus Canola
 

Date seeded Emergence Yield   plants/m2 plants/fl2 kg/ha bu/ac May 6th 35 3 1456 26 May 18th 79 7 1232 22 May 31st 70 6 1400 25 May 6th, reseeded 31st 62 6 1512 27 Least Significant Difference 17 2 168 3

Therefore, the decision to reseed is often difficult and must be based on thorough agronomic and economic assessments, including an accurate evaluation of seedling mortality, surviving stand density and yield potential of the existing stand versus reseeding. Growers who still have canola left to seed should be reassessing the maturity suitability of their chosen varieties. The accumulation of temperature or Growing Degree Days (GDDs) has a major influence on days to maturity for canola. In the short and mid season zones of western Canada, maturity for B. napus varieties will range from 95 to 125 days, depending on the growing season heat accumulation. B. rapa varieties usually range from 80 to 115 days to maturity. First, find out how many days to maturity are required for the variety that is to be seeded. Usually the variety will be rated as so many days earlier or later or equal to the check. Using a typical first late summer/fall frost date, count back the days to maturity to get to the safe seeding date. For example, if the first frost is August 25 on average and maturity of the check in the area is 103 days, counting back gives a safe seeding date of May 17. If the variety to be seeded is five days earlier in maturity than the check, this means that in a typical year, seeding up to May 22 would be acceptable for that variety. If the variety does not meet the requirements, ask your local retailer to suggest other suitable varieties.

Manitoba growers can check the following link to determine their frost-free days: http://www.gov.mb.ca/agriculture/climate/waa50s00.html

Alberta growers can check the following link to determine their frost-free days: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex10

The delay in seeding progress due to wet weather in Manitoba has led to many questions regarding the feasibility of broadcast seeding. In general, broadcast seeding is not recommended due to generally lower yields when compared to drilled seeding. However, when confronted with wet conditions that limit equipment flotation plus the risk of fall frost due to further delays in seeding, broadcast seeding is a practice that may be an option for some producers. Here are some tips for enhancing the success of broadcast seeding.
* Increase seeding rates slightly to compensate for non-uniform seed depth.
* Consider lightly cultivating (2-4 cm) or harrowing to incorporate the seed into the soil if soil conditions allow.
* Avoid creating lumps or clods during cultivation or straw piles with harrows or cultivators.
* Increase phosphorus (P) fertilizer rates by 50% to compensate for the reduced efficiency of broadcast P.

Weed growth continues to be slow in many areas due to cool conditions. Growers are reminded to get on their hands and knees to do a proper assessment of early and small emerging weeds and ensure that spraying is done early to avoid yield losses due to early weed pressure. Flea beetles have been reported in western Saskatchewan, southern Alberta near Seven Persons, central Alberta near Didsbury, Acme, Wetaskiwin and St. Albert, and many areas in the Peace region. Stem feeding of canola by flea beetles has been reported in many of these areas. Cool conditions can cause flea beetles to remain close to the soil surface to retain heat, leading to high flea beetle pressure and stem feeding. . Stem feeding can quickly girdle the stem and the plant dies within two to three days (To view stem feeding of flea beetles, download this image:
http://www.canola-council.org/slides/pests/insects/Fleabeetlestemfeedinghs.zip).

Ensure that field scouting includes stem monitoring as well as leaves. If stem feeding is noted, ensure the damage is caused by flea beetles and not cutworms. Refer to the May 5 report for further information on flea beetles: http://www.canola-council.org/production/agronomy_may05.html

Refer to the following link for more information on stem feeding by flea beetles: http://www.gov.mb.ca/agriculture/news/insect/miu03_05_27.html

Cutworms continue to be noticed in areas of southern Alberta near Cayley, central Alberta near Vermilion and Vegreville and wireworms near Cremona and Cayley. One report of cutworms near Vegreville was confirmed instead to be crane fly larvae, which are not a pest. Refer to the following link for more information on crane fly larvae: http://www.fcps.k12.va.us/StratfordLandingES/Ecology/mpages/crane_fly.htm

Refer to the May 12 report for more background information on cutworms and
wireworms: http://www.canola-council.org/production/agronomy_may12.html

Any questions regarding this overall report should be directed to John Mayko, Agronomic Research & Extension Manager with the Canola Council of Canada at maykoj@canola-council.org- ph/fax: 780-764-2593.

For specific questions regarding regional issues associated with this report, please consult one of the following Canola Council of Canada regional agronomists or provincial oilseed specialists:
Derwyn Hammond, Agronomist, Manitoba, hammondd@canola-council.org, 204-729-9011
Rob Park, Manitoba Agriculture, Food & Rural Initiatives, rpark@gov.mb.ca, 204-745-5665
David Vanthuyne, Agronomist, Eastern Saskatchewan, vanthuyd@canola-council.org, 306-782-7799
David Blais, Agronomist, Western Saskatchewan, blaisd@canola-council.org, 306-895-2122
Jim Bessel, Senior Agronomist, Northeastern Saskatchewan, besselj@canola-council.org, 306-373-6771
Bill Greuel, Saskatchewan Agriculture, Food & Rural Revitalization, wgreuel@agr.gov.sk.ca, 306-787-2756
Doug Moisey, Agronomist, Central Alberta, moiseyd@canola-council.org, 780-645-3624
Christine Mardell, Agronomist, Peace River Region, mardellc@canola-council.org, 780-518-1513
Nancy Muchka-Dahl, Agronomist, Southern Alberta, muchkan@canola-council.org, 403-625-1596
Murray Hartman, Alberta Agriculture, Food & Rural Development, murray.hartman@gov.ab.ca, 403-782-8024
Kerry Clark, BC Ministry of Agriculture, Food & Fisheries, Kerry.Clark@gems9.gov.bc.ca, 250-787-3213

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; Cargill; 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.