Canola Council
Canola Watch
2003 Canola Watch Reports
Canola Crop Watch Report No. 5
Western Canada – May 28, 2003
Canola seeding is winding up in most areas. In Manitoba, only 10 to 20% of the crop remains to be seeded, primarily in the southwest and northwest. In Saskatchewan, approximately 80% of the canola has been seeded with the southeast farthest behind (60%) due to excess moisture. Canola seeding in Alberta is about 80 to 90% complete with some areas yet to be seeded to B. rapa (mainly in the Peace region) and early maturing B. napus varieties. Seeding in the BC Peace is virtually complete.
Soil moisture conditions
across most of western
Canada remain good to
excellent for germination
and early crop development.
However, surface moisture
levels are becoming dry
in Manitoba near Dauphin
and Newdale, in many areas
of northern Saskatchewan,
in northeastern Alberta
and in the north Peace.
Timely rains will be needed
soon in these areas to
maintain crop yield potential.
For current maps of moisture
conditions from PFRA check
the following links:
http://www.agr.gc.ca/pfra/drought/drprec4_e.htm
http://www.agr.gc.ca/pfra/drought/drprecw_e.htm
http://www.agr.gc.ca/pfra/drought/prgrowing_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
The latest crop report
from Saskatchewan Agriculture,
Food & Rural Revitalization
is available at:
http://www.agr.gov.sk.ca/docs/reports/crop_report/crprpt030526.pdf
Windy conditions were noted throughout many areas of Saskatchewan causing canola to be blown out, particularly in the northeast and northwest. The winds have also exacerbated the dry surface soil conditions. ‘Sand-blasted’ canola has been reported.
Poor canola emergence has been reported in some early seeded fields in southwest and northeast Saskatchewan and southern Alberta. Disease, frost, soil crusting and insect pests can reduce plant stands this time of year. Cutworm, flea beetle and frost damage have been covered in previous reports. Damping-off or seedling root rot complex in canola is a likely culprit in early seeded fields this year. Early infection (just after seed germination) causes pre-emergence rot, and infected seedlings do not emerge. Infection at or after emergence leads to damping-off, also called seedling blight or wirestem. The seedling will emerge, stop growing and then topple over. The stem or hypocotyl will be noticeably constricted at or below the soil surface, and usually turns brown, hence the name "wirestem". Surveys have found that the main pathogen is Rhizoctonia solani while Pythium and Fusarium species are minor players. Wirestem is mainly affected by temperature. Prolonged cool soil temperatures after seeding for 10 days or so will increase the disease incidence. Our winter-like early May this spring in Alberta certainly qualifies for prolonged cool conditions! Seed treatments provide reasonable protection against the pre-emergence rot, and some protection against damping-off. Prolonged cool weather could diminish the protection of seedlings emerging several weeks after seeding. There are no differences between varieties.
Some reseeding has taken place in areas of Manitoba and northeast and west-central Saskatchewan due to earlier frosts, particularly in early seeded fields. Each year there are fields that suffer from poor emergence or damage after emergence by 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 seeding season 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.
Weed growth has continued to be heavy for this time of year due to favourable moisture conditions. Split applications of herbicides on emerged crops are being performed or contemplated in many areas due to the high populations of grassy weeds. Growers are encouraged to control weed flushes early, to maintain crop yield potential.
Water quality
is key to achieving proper
performance of many herbicides,
particularly with glyphosate
and many grassy weed products.
Check the following link
on water quality from
Saskatchewan Agriculture,
Food & Rural Revitalization:
http://www.agr.gov.sk.ca/docs/crops/integrated_pest_management/weed_control/waterquality.asp?
firstPick=Crops&secondpick=Integrated%20Pest%20Management&thirdpick=Weed%20Control
More flea beetles have been noticed in many areas of Manitoba, Saskatchewan and southern Alberta. Tips for monitoring and assessing flea beetle damage of emerging crops was discussed in the May 7 crop report (http://www.canola-council.org/seed/canola-watch/watch-may7.shtml).
The following figure may help in assessing the level of flea beetle feeding.
Additional information on assessing flea beetle feeding damage is located on the following Manitoba Agriculture web page: http://www.gov.mb.ca/agriculture/crops/insects/fad01s00.html.
Grasshoppers are beginning to hatch in a number of areas, and it is important for growers to recognize that not all species of grasshopper are pest species. The two predominant pest species are the two-striped grasshopper and the clear-winged grasshopper.
According to Dan Johnson with AAFC Lethbridge, the two-striped grasshopper is already hatching while the clear-winged grasshopper will begin hatching about May 30. The two-striped grasshopper will appear light brown and about 1/8" long. Smaller numbers of the migratory grasshoppers also have hatched. He suggests that the following species can be ignored this year:
moderate-size or large
hoppers seen before late
May;
grasshoppers with yellow
or red wings in flight,
any time of year;
grasshoppers that click
or buzz when they fly,
any colour, any time of
year; and
grasshoppers that make
"scratching"
sounds in the grass or
crop, any time of year.
When scouting for grasshoppers
use ‘foot-square’
counts to rate the field.
This is simply the number
of grasshopper nymphs
that jump from a square-foot
area as you walk toward
it (Field Scouting Guide,
Manitoba Agriculture and
Food, 2002 edition). To
do a field survey, start
at one corner of the field
and walk diagonally past
the center of the field,
then turn and walk straight
out to one side of the
field. Make at least 20
of these foot-square counts
while walking. Divide
the total number of grasshoppers
from the 20 counts by
2 to estimate the number
of grasshoppers per m2.
While an economic threshold
for grasshoppers in canola
is not currently available,
preliminary research indicates
that it is probably about
15 grasshoppers per m2.
More information on thresholds
and grasshopper species
is available at:
http://www.agr.gov.sk.ca/DOCS/crops/integrated_pest_management/insects/grasshopperff.asp?
firstPick=Crops&secondpick=Integrated%20Pest%20Management&thirdpick=Insects
Cutworms have
again been noticed in
Manitoba, particularly
in areas that experienced
damage last year. See
last week’s crop
report for a discussion
on cutworms:
http://www.canola-council.org/seed/canola-watch/watch-may22.shtml
As well, wireworms have been noticed in some areas of north-central and northeast Saskatchewan. For more information on wireworm identification, scouting and control, visit this Manitoba Agriculture Web page: http://www.gov.mb.ca/agriculture/crops/insects/fad28s00.html
Direct overall questions regarding this report 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, 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 & Southern
Alberta, moiseyd@canola-council.org,
403-553-2829
Christine Mardell, Agronomist,
Peace River Region, mardellc@canola-council.org,
780-518-1513
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 Crop 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, James Richardson International, 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.
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