Canola Watch 14: Insects still active, tips for harvest
In This Issue
Insect roundup
How to harvest fields at various stages?
Be Export Ready: Know pre-harvest Intervals and follow product registrations
Best time to swath: 50-60% seed colour change
Coming events
Questions and contacts
Issues of the week:
July 28, 2010 — With more canola fields going into early pod-filling stages, the insect watch enters a critical phase. Spraying for lygus, bertha armyworm and diamondback moth larvae has occurred in some regions. While scouting for insects, don’t forget to take a look for blackleg and clubroot — for next year’s rotation planning.
Crop and weather reports:
Peace (B.C. and Alberta): Dry conditions continue in the south and central Peace. Some areas got a few tenths here and there, but most fields did not get enough moisture to be of any benefit. Hawk Hills north to La Crete/Ft. Vermilion and to the east are still getting good moisture. Earliest fields in these areas are finishing flowering, which puts them behind drier areas of the Peace.
Alberta: Warm temperatures in the south have moved canola along, but they’re still behind — with most canola at 10% to 70% flower. In west central regions, canola continues to range from good to excellent. Favorable moisture and moderate heat have produced some heavy canopies with 6-foot stands. Most areas in the east could use a good rain to finish off the crop. Earliest seeded crops in the central regions are at early pod stage. In general, crops are one to 2 weeks behind. Crops damaged by hail storms from a couple of weeks ago are recovering and reflowering. The concern now is whether they will mature prior to a fall frost. Read the Alberta crop report.
Saskatchewan: Canola is advancing quickly with warm-to-hot weather and only scattered showers, for the most part. Crops are filling in nicely in the west and in some eastern and northern areas. In the wettest areas of eastern Saskatchewan where canola has not recovered, growers are taking acres out of production. “That area is seeing a continuous drop in harvestable acres,” says Jim Bessel, CCC senior agronomy specialist. Crops are one to 2 weeks behind normal. Read the Saskatchewan crop report.
Manitoba: Canola has improved after a generally warm dry week, although many crops in the northwest and Interlake will remain short and thin due to relentless moisture stress earlier. Swathing has begun on a few early canola fields in the central and southeastern regions, but generally most reports indicate a week or 2 before swathing gets underway, especially in the northwest. Read the Manitoba crop report.
Quick hitters
Blackleg is widespread in southern Manitoba. Disease severity on infected plants is still low right now, but severity can increase dramatically with hot weather. This level of infection is unusual to see at this stage. Growers with infected fields should be prepared for some yield losses. Staging is too late for protective spray, but scout fields for damage and plan to rotate those fields out of canola for a few years.
Alternaria is showing up in B. juncea canola. This is early and could cause some serious yield losses. Start scouting now, looking for lesions on the stem. It will move up the plant and eventually get to the pods, as shown in the photo below. The best staging for alternaria control is listed as 90% petal fall/late flowering to early green pod stage. Pre-harvest intervals vary from 7 to 30 days. Juncea, like Polish, is more susceptible than napus because it has less of a waxy barrier than napus.
Light stands encourage some growers to consider straight combining. To swath these stands would mean a higher risk for swath blowing, and some crops just don’t have the stalk counts to hold up a windrow. But straight combining has its own risks when plants whip against each other in the wind. Click here to read the CCC factsheet "Straight Combining Success Depends on Many Variables."
Tank mix when spraying out poor canola fields. Some growers with very poor canola crops want to cut their losses and set up crop management plans for next year. The photo below shows one such field around Melfort, Sask. When spraying out a canola field, consider adding a broadleaf control component to the glyphosate application — even if the field is not an RR variety. This will control all canola, regardless of the system.
Insect roundup
—Diamondback moth larvae scouting and spraying continues this week. Action threshold at the podding stage is 20 to 30 larvae per 1/10 of a square metre — or roughly one square foot. Click here for the diamondback moth report from last week.
—Lygus bug numbers are at thresholds in parts of the Peace and rising in Manitoba’s northwest. Even a field near Canwood, Sask. was sprayed for lygus this week. See the Tables 2 and 3 below for thresholds.
—Bertha armyworm numbers are nearing threshold in the La Crete area of the Peace, around Regina and Moose Jaw. Continue to scout as the area affected is likely larger than original reports indicate. See Table 1 below for thresholds.
—When a crop has more than one insect species feeding on flowers, buds and pods at the same time, consider the “additive” effect when assessing thresholds. For example, if you have diamondback moth and cabbage seedpod weevil in the same field and if both are at 50% to 60% of their economic spray thresholds, spraying may provide an economic benefit — especially if the crop is already stressed.
  
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How to harvest fields at various stages?
Many growers, especially in the eastern Prairies, have fields at varying stages. Higher land may have crop at podding stages, while once-flooded lower areas are recovering but still flowering. One harvest plan is to swath these fields at two timings— if the hope is to salvage the late-developing areas.
Section off fields based on staging and yield potential. Know where the greatest yield potential is within the field and plan to focus on protecting it the most. The greatest yield potential includes the plants with most seeds but also earliest maturing to escape a fall frost. Waiting to swath the whole field at once may put these top areas of the field at risk of pod shattering.
Other options to consider while scouting:
— Is the staging so variable that a desiccant may be needed to hasten maturity on the latest plants?
—Would swathing be better than straight cutting or vice versa?
—Is there a lot of green weed growth that will require a pre-harvest application?
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Be Export Ready: Know pre-harvest Intervals and follow product registrations
Considering pre-harvest weed control, desiccation or late insect and disease control? Then look at the pre-harvest interval (PHI) of a product before spraying. PHI is the number of days that the crop should not be harvested after application of a pesticide. Harvest means cutting or swathing. If the crop is harvested before the indicated interval has elapsed, there could be unacceptable pesticide residues in or on the harvested seeds.
Pre-harvest intervals are listed on the labels of pesticides and under the “Restrictions” section of individual product descriptions in the provincial guide to crop protection. Click your province for a link to your guide: Alberta Saskatchewan Manitoba
Always be Export Ready: Ensure the product is registered for the intended use and registered to be used on the crop at that stage.
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Best time to swath: 50-60% seed colour change
Research indicates that the optimum stage to swath canola for both yield and quality is up to an average of 60% seed colour change (SCC) on the main stem.
To assess SCC, open up pods on the main stem and look at the colour of the seeds. Pod colour is not a good indicator. Some varieties will show pod colour change long before the seeds change, while the opposite is true of other varieties — pods are green while seeds are brown.
For growers faced with uneven maturity within fields, the best approach is to swath when the most mature plants are close to 60% SCC — provided that the least mature plants are showing some seed colour change at the base of the main stem and that seeds in the upper pods (and branches) are dark green and firm. This will minimize yield loss from seed shrinkage and improve the odds that the seed will cure, although it will likely take longer and may require some more moist conditions. Swathing prior to 15 to 20% seed colour change will likely reduce yield potential and could contribute to green seed issues under hot and/or dry conditions.
For more information on harvesting a multi-stage crop, click here to download a 4-page PDF.
Also click here to download the CCC’s "Canola Time of Swathing Guide"
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Coming events
Controlled-traffic farming (CTF) Alberta is hosting a tour near Morrin, July 29 from 1:00 to 6:00. Click here for more information.
Combine Clinic is coming to the Peace region, August 4, 8:30-3:30 near Fairview, Alta. Pre-register with Michelle at PARDA at 780-835-9158. Click here for more information.
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Questions and contacts
If you have general questions about Canola Watch, direct them to Jay
Whetter, whetterj@canolacouncil.org
or 807-468-4006.
If you have questions on regional issues, contact one of the following
Canola Council of Canada regional agronomists or provincial oilseed
specialists:
Derwyn Hammond, senior agronomy specialist, Manitoba, hammondd@canolacouncil.org,
204-729-9011
Jim Bessel, senior agronomy specialist, Central Saskatchewan, besselj@canolacouncil.org,
306-373-6771
Tiffany Martinka, agronomy specialist, Eastern Saskatchewan, martinkat@canolacouncil.org,
306-231-3663
Clint Jurke, agronomy specialist, Western Saskatchewan, jurkec@canolacouncil.org,
306-821-2935
Troy Prosofsky, agronomy specialist, Southern Alberta, prosofskyt@canolacouncil.org,
403-332-1412
Doug Moisey, senior agronomy specialist, North East and East
Central Alberta, moiseyd@canolacouncil.org,
780-645-9205
John Mayko, senior agronomy specialist, West Central Alberta, maykoj@canolacouncil.org,
780-764-2593
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, B.C. Ministry of Agriculture and Lands, Kerry.Clark@gov.bc.ca,
250-784-2559
Venkata Vakulabharanam, Saskatchewan Ministry of Agriculture, Venkata.Vakulabharanam@gov.sk.ca,
(306)787-4668
Ingrid Kristjanson, Manitoba Agriculture, Food and Rural
Initiatives, ingrid.kristjanson@gov.mb.ca,
204-746-7504
This report is supported by each of the provincial canola grower
associations. For more information on some of their activities, check
out the following links:
The Alberta Canola Producers Commission (ACPC) has a free e-newsletter
called Alberta Canola Connections. Visit canola.ab.ca
and click the sign-up icon on the right site of the homepage.
In Manitoba, sign up for the Manitoba Canola Growers Association
newsletter at Canola Growers E-update by visiting www.mcgacanola.org
For information on activities in Saskatchewan, visit SaskCanola at www.saskcanola.com.
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