Story Posted: August 11, 2010

Canola Watch 16: Be Export Ready - Keep Pre-Harvest Intervals Top of Mind

Swathing is underway in parts of Alberta (Peace) and Saskatchewan, but most regions are 1-2 weeks behind. Fields in wettest areas are delayed 3-4 weeks. More heat is needed to speed crop development. Combining of April-seeded fields has started in Manitoba. This week, we've got swathing tips for thin stands, an update on late-season insects and controls, tips on pre-harvest weed control vs. desiccation, cautions about combining in the heat, and a reminder: Be Export Ready, pay attention to pre-harvest intervals.

Crop and weather reports
Peace (B.C. and Alberta): Hot, dry weather prevailed last week. Swathing has become general in the earliest and thinnest crops and will become general in other areas within a week or so.

Alberta: Crops in the south and central region look good to excellent. Farmers are cautiously optimistic because crop development is 2-3 weeks behind. Crops are more advanced the further north you go. Heat is needed to help hasten maturity. Read the Alberta crop report.

Saskatchewan: Isolated thundershowers dropped up to a couple of inches of rain in western and eastern regions. Hail was reported at Wilke. Earliest fields in the western side of the province are a week away from swathing while majority of fields western areas are two weeks behind. Swathing has begun in the east near Weyburn, Chamberlain, and Moose Jaw areas. Fields further north are a week to two weeks away. In northern areas, crops north of Saskatoon are most advanced (earliest fields a week away from swathing) and most productive. Crops in the northeast are at least two weeks behind. Read the Saskatchewan crop report.

Manitoba: Hot and humid conditions were common last week.Thundershowers were common in the northwest with hail in the northern part of the Swan River Valley. About 25% of the canola is swathed in the southwest and about 35 to 50% swathed in central and eastern regions. A few of the very earliest, April-seeded fields have been combined. The northwest and north Interlake are generally less advanced with crops at least a week to ten days from swathing. Read the Manitoba crop report.

Quick Hitters
Late season spraying – adhere to pre-harvest intervals
Pre-harvest interval (PHI) refers to the number of days that the crop should NOT be harvested after application of a pesticide. Harvest in this context means cutting or swathing, so this could also be called the pre-cutting interval. If the crop is harvested before the indicated interval has elapsed, there could be unsafe or unacceptable residues of the pesticide remaining 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 provincial guides to crop protection. Take note of the required pre-harvest interval and allow adequate time before harvest. Also, ensure that the product is registered for the intended use and registered to be used on the crop at that stage. Following pre-harvest intervals is critical to keeping all canola Export Ready.

Keep scouting for late-season insects
Lygus bug populations at or above economic thresholds have been found in the highway 2 and 23 corridor (north of Lethbridge and south of Calgary) and in central areas around Olds, Boyle and Barrhead. Farmers near Provost and Two Hills are battling high populations of lygus, diamondback moth and bertha armyworm. Click here to see threshold tables for key insects. Be Export Ready and keep PHI top-of-mind when choosing a late-season treatment. For more on PHI, listen to Denise Maurice, CCC vice president of Crop Production, speaking on ACPC radio. Or click your province for a link to your guide to crop protection: Alberta , Saskatchewan , Manitoba.

Click here to hear a radio interview on diamondback moth and its natural enemy with Dr. Lloyd Dosdall, University of Alberta. Click here to sign up for a Diamondback Webinar discussing diamondback biology and its control with Dr. Dosdall to be held Thursday August 12 at 8:30 am.

Don't rush to swath
Swathing at 50 to 60% seed colour change on the main stem is generally optimal for both yield and quality. If growers can't wait that long, at a minimum make sure green seeds are firm when rolled between the thumb and forefinger. 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. Hot, dry conditions in Manitoba this past week caused significant pod colour change in some fields. Sun scald or natural senescence is making the canopy look ripened but often the seeds within remain green. Be sure to examine seeds within the pods on the main stem to gauge timing accurately.

For more on swathing timing, click here to see a CCC video.

Pre-harvest weed control
With swathing imminent in many regions, there are lots of questions about pre-harvest weed control vs. desiccation. Glyphosate is not a desiccant and will not hasten seed maturity. Glyphosate for pre-harvest weed control in canola should be applied at 30% seed moisture which is about 30 to 40% seed colour change. Apply 7 days before swathing for full translocation within the target weeds, generally Canada thistle and quackgrass. Research has shown that post-harvest can be the best time to control dandelion. This year's thin fields have high weed populations in some cases. If desiccation is required to manage uneven maturity in glyphosate tolerant crops, Reglone can be applied but will only provide top-growth dry down for weeds. Scout fields thoroughly to know what weeds are present and what product or timing is needed.

Condition and cool after combining
It is critical to cool and condition canola after putting it in the bin. Canola binned at high temperatures, even at seed moisture levels considered dry, can begin to spoil in storage. Crops with lots of green material present (weeds or less mature low spots) can have a high chaff load and quickly start to heat when stored. Use aeration to bring down the temperature and/or moisture of binned canola to below 15 °C and 8% moisture for long term storage.

Growers needed for combine loss study
As part of a CCC-funded project, researchers are looking for growers in select regions to take part in a combine-loss survey. Growers remain anonymous and researchers do most of the work. Growers around Lacombe and Edmonton, click here for more information. Growers around Saskatoon, click here. And growers around Winnipeg, click here.

Clubroot shows up in resistant hybrids
Growers who seeded clubroot-resistant hybrids should know that low-level infection — up to 8% of plants — is normal for these hybrids. These off-types will be scattered uniformly through the stand.

If resistant hybrids have levels higher than this, a patch of susceptible volunteers is the most likely reason. Volunteer canola densities can easily exceed 10 plants per square foot in canola-on-canola rotations, and will be part of the current crop unless a different herbicide-tolerant system was used. With canola-wheat-canola rotations, volunteer canola in the next canola crop may persist at levels of about one plant per square foot in certain situations.

If volunteers cannot explain high infection rates in resistant varieties, then growers should contact their seed rep for further diagnosis.

Click here for more information on scouting for clubroot infection.

For more on identification, prevention and management of clubroot, visit the Clubroot website.

Should growers straight combine a thin crop?
Growers with thin crops are wondering whether straight combining is better than swathing. Straight combining tends to work best on thick stands with plants meshed together to prevent whipping in the wind. But thin stands are at risk of wind damage whether swathed or straight combined. When thin stands are swathed, often there isn't enough stubble to hold the windrow in place and prevent it from rolling in the wind.

If growers decide to swath thin crop, keep the following recommendations in mind:

• Swath parallel to the typical prevailing winds in the area.
• Cut plants as high as possible, just below the lowest pod. That will provide the highest stubble possible to keep the windrow in place.
• Use a properly-adjusted swath roller to push down the swath so the edges are nestled into the stubble. Because the swath will be on or close to the ground, curing and/or dry down time may take longer.

Should I use a pod-sealant?
Questions continue about pod sealants. Limited western Canadian research to date has produced variable results. If farmers do use them, leave a test strip as a comparison and an assessment can be made to see if the sealant made a difference on yield. Ensure application timing is optimal and water volumes are adequate to maximize the odds for success. Crops that are hail damaged or have a high disease incidence, such as alternaria, may not be good candidates for a pod-sealant. Lesions or hail scars on pods have damaged the outer waxy layer and the physical integrity of the pods and have increased the risk of pod shattering and have the potential to disrupt the pod-sealant's effectiveness.

What are those odd-looking plants?
A number of odd looking plants have generated calls and questions lately. Some are tall, monstrous looking plants. These are called off-types. Many seed companies conduct seed multiplication in the southern hemisphere and these off-types result when pollen transfer occurs with winter canola. Another anomaly showing up is aster yellows. Affected plants show a bunched appearance at the tips of branches where blue-green, sterile, hollow bladders are formed in place of normal pods. Normal appearing pods may be present on the lower portions of infected plants but fail to set seed. Aster yellows is caused by a phytoplasma, a plant pathogenic micro-organism. The phytoplasma is carried from plant to plant by sap-sucking leafhoppers. Off-types and plants infected with aster yellows are usually found in extremely low levels within a field and are not economic. A third odd-looking plant symptom being reported this year is stag head or white rust. This plant disease thrives under wet conditions and appears as white to cream-coloured pustules on the underside of leaves from the seedling stage onward. Following infection of the stems and pods, raised green blisters form that turn white during wet weather. The most conspicuous symptom is the presence of swollen, twisted and distorted inflorescences called "stagheads" that become brown, hard and dry as they mature. Stag head is not an economic pest of canola except in B. juncea varieties.

	Canola infected with aster yellows.

	Canola infected with white rust, commonly known as stag head.

7 swathing tips for 2010
1. Scout for disease prior to swathing. Assess levels to determine if premature ripening or pod damage from alternaria black spot may necessitate swathing earlier than normal — before seed shatter starts. Fields with lots of diseased plants may also be poorer candidates for straight cutting due to the increased shattering risk.

2. Hail damage can cause crops to mature unevenly. When swathing a hailed crop, assess the seed-colour change at the earliest and highest-producing parts of the field, especially if the delayed maturity creates a high risk for fall frost damage.

3. Check weed pressure. Green biomass in the swath will extend the curing time, and weed seeds and green plant material can be starting points for heating in storage. Fields with high weed counts may benefit from a pre-harvest spray to dry them down.

4. When to swath. The best timing for yield and quality is when 50% to 60% of seeds on the main stem are turning from green to brown. For more on this, click here to read the CCC's "Canola Time of Swathing Guide."

5. Lay swaths parallel to the direction of prevailing winds. This reduces the risk of swaths blowing and pods shattering.

6. Set the roller low enough to anchor swath into standing stubble with slight pressure. Use a roller that tucks swath edges down into stubble.

7. Large dense swaths tend to take longer to condition and cure canola before combining. Thin swaths lying flat on the ground may also take longer.

When to swath multi-stage crops
Many fields in the rain-soaked regions have advanced crop on the high ground and much later crop in the low ground. These fields require some harvest planning. Does a grower swath the high ground first and the low ground a couple weeks later? That may be the best option as long as the low ground looks like it will mature in time and if the low ground has the potential to generate worthwhile volumes. Otherwise it may be simplest to cut the whole field when the majority of the crop is ready.

Key to the decision is this: Don't put the best and biggest part of the crop at risk of shelling in order to save a few acres of later, higher-risk and possibly low yielding canola.

Click here to download a 4-page PDF called "Swathing and Harvesting Multiple Stage Canola Crops."

Coming events
Clubroot Crop Walk, August 17 at Edmonton/Namao area with CCC senior agronomy specialist John Mayko, ACPC director Jody Klassen, Murray Hartman provincial oilseed specialist and U of A pathologist Dr. Stephen Strelkov. Walk starts at 10:00 and goes to 1 pm. Click here for location and details.

Canola Crop Walk, August 18 at Vulcan with CCC agronomy specialist Troy Prosofsky and ACPC director Lee Markert. Come learn about varieties, timing of swathing, insects. Walk starts at 8:30 and goes to noon. Click here for location and details.

Pre-harvest/Late Summer Diagnostic Clinic at the Ian N. Morrison Research Farm in Carman, Man., Wednesday, August 18 from 1:00 - 4:00 p.m. Canola topics include harvest management. Registration is free for Crop Diagnostic School participants and $25 (cash or cheque at door) for others. Call 204- 745-5663 to register.

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.

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