Story Posted: June 22, 2011

Canola Watch: Water stress, Timely spraying, Sclerotinia prep

Issues of the week: Rain in the western Prairies has increased optimism, especially in the Peace River region, central Alberta and parts of Saskatchewan that needed rain. But wet fields will delay timely weed control in all regions. Aerial spraying may be the best option to get weeds controlled before the crop outgrows the safe stage for application.

Moisture also increases the likelihood of economic damage from sclerotinia. The combination of high yield potential, good canola prices and favorable conditions for disease development could make fungicide spray a good economic decision for many canola fields.

Growers are reminded this week to note the crop insurance deadline for filing seeded acres reports. Also, if you have a rain delay, take a moment to check the condition of any canola in storage.

Crop and weather update
Peace Region (B.C. and Alberta): Welcome rains of 2" to 5" fell across most of the region early this week. Rains bypassed the northern Peace region and fields in that area are experiencing some drought stress.

Alberta: Rain blanketed Alberta, with a few tenths to 2" in the south and an average of 2" in central regions. Some areas got 5" to 6". Central Alberta needed the rain. Earliest canola is bolting. A few warm days would help crops advance quickly. Alberta crop report.

Saskatchewan: Rain fell across the province, ranging from 1/2" to 3" in the southwest, 2" to 5" across the north, and at least that much in the southeast. Dry areas welcomed the rain. The southeast didn't need any, and some areas (Weyburn, for example) now face extreme flooding. Earliest crops are bolting. All crops would benefit from some heat. Saskatchewan crop report.

Manitoba: Rainfall varied from 1/4" in the east to 6.5" in the southwest where they didn't need any rain at all. Many canola fields are under considerable moisture stress. The province needs a long stretch of warm days without rain. Manitoba crop report.

	Accumulation for the week of June 14-20

	Percent of normal for April 1 to June 20

Weed control window closing
Rain has set back weed spraying. Early canola crops are near the end of their spray windows, even though some fields have not received a first pass and some fields got a first pass but need a second.

Label application windows:

Glyphosate: Anytime up to and including the 6-leaf stage of canola.
Liberty: Cotyledon stage up to the early bolting stage of canola.
Odyssey/Absolute: 2- to 6-leaf stage of canola.

Herbicides applied after the approved crop stage could cause early flowers to be aborted. (Click here to learn how.) Growers are advised to assess what will create the greater losses - weed competition or loss of the first set of flowers? Canola typically produces more flowers than it can support. The plant can produce more flowers to compensate for early flowers that were lost, provided stress later in the flowering period does not limit this ability.

Aerial application may be required to spray within the application window if fields are too wet for the ground rig. Avoiding ruts is an additional benefit. Click here for aerial spraying tips. Note that Centurion has received emergency registration for aerial application on canola for 2011. For more information, click your province for a link to your guide to crop protection: Alberta Saskatchewan Manitoba

Minimize ruts with ground rigs. If you plan to use the field sprayer, wider tires and lower tire pressures can improve sprayer flotation and reduce rut depth. If the operator doesn't have time to switch tires, make ruts parallel with the intended direction of travel for the swather and combine so growers can keep up their harvest speed.

If drift risk is keeping you off the field, consider a coarser spray to reduce drift. Click here for Tom Wolf's tips on how to reduce the drift risk. Click here for photos of drift damage to canola.

Water stress reduces herbicide tolerance and nutrient uptake
Heavy rains the past week have put a lot of canola under pools of water. This water stress can make canola more susceptible to herbicide damage. Stress in the canola plants can lead to slower metabolism of the system herbicide, and plants are set back. In areas under extreme stress this year, damage appears to be enough to kill plants where sprayer booms overlap, in some cases.

When weeds are large, resist the temptation to increase herbicide rates if the crop is under stress.

Water stressed canola may also turn yellow because roots starved for oxygen can't take up nutrients. Nutrient may be present at sufficient amounts, but the crop can't utilize it.

If considering a nutrient top up to rescue the crop, wait until the ground dries up and roots can get working again before making that investment. Topdressing fertilizer may help when new green leaves start growing and when good growing conditions return.

Sulphur in the form of ammonium sulphate can provide an economic return when applied up to the bolting stage. Nitrogen applied past the 6-leaf stage is unlikely to provide an economic benefit.

Still time for a crop nutrition top up
Rainfall has renewed optimism in many key canola growing regions. Growers still have time to top up nitrogen and sulphur to take advantage of higher yield potential. Nitrogen should be applied before the 5-leaf stage to provide a strong economic benefit. Sulphur can be applied up to bolting. Click here for top up tips and photos of sulphur deficiency.

Apply whatever rate you feel is appropriate based on how much was applied earlier and the new yield potential of the crop. While there may be some leaf burn from high rates of nitrogen, the crop can usually grow through this damage without significant losses.

Efficacy can be very good for in crop applications. The key is to get a rain AFTER application to limit losses and move nutrient into the root zone. Uptake through leaves is minimal.

Rain that creates soil saturation can actually increase nitrogen losses due to denitrification, especially in fields with high residue. Crop residue, which provides a carbon-rich, nitrogen-poor food source for soil bacteria, will tie up (immobilize) fertilizer nitrogen stranded on the soil surface or in the shallow top layer. Whether using urea (dry) or UAN (liquid), Agrotain can limit losses while waiting for rain.

To minimize the effects of leaf burn, consider this tip: Apply liquid products when leaves are wet so the product runs off, but apply granular products in dry conditions since prills are less likely to stick to plant leaves.

Factors to consider before a top up:
-Nitrogen topdressing can extend the vegetative period and delay crop maturity. Consider the calendar date and the fall frost risk when making a nitrogen top up decision.
-As canola plants grow their roots will start to access sulphur reserves that moisture carried lower into the soil profile. Growers who have been applying recommended rates of sulphur may find that topdressing produces a smaller economic return than it does for those who have cut sulphur rates.

Disease update: Rain raises sclerotinia threat

Significant sclerotinia infections were reported in most regions last year, creating the potential for lots of spore production across the Prairies this year. If fields are moist at the time of flowering, and canola has good yield potential (e.g. 30 bu./ac. or more), then it will probably pay to spray a fungicide to limit sclerotinia losses.

The message this week is to consider the threat and budget for action. Spraying is not effective until the flowering stage, which is still a few days away for the earliest crops.

Areas that have been wet all spring will likely have apothecia emerging in any fields that were seeded to a susceptible crop like canola, lentils or sunflowers last year. Apothecia release the sclerotinia ascospores that are dispersed in the wind and land on canola petals.

Areas that had been dry but received rain this past week will likely see apothecia starting to emerge in a week or so. Apothecia need moisture to trigger their growth, and after a rain it takes 10-12 days for them grow to a point where they release spores. The Prairies could face a significant release of ascospores next week and if moist conditions continue, this release will continue throughout canola flowering.

With good canola prices, good yield potential and lots of moisture (so far), fungicide application could pay off for many growers this year.

	Sclerotinia apothecia. Source: Faye Dokken-Bouchard, Saskatchewan Ministry of Agriculture

	Sclerotinia apothecia are quite small. Source: Faye Dokken-Bouchard, Saskatchewan Ministry of Agriculture

	Source: Faye Dokken-Bouchard, Saskatchewan Ministry of Agriculture

Blackleg: The application window for a fungicide to provide additional protection against early blackleg infection (which is the most damaging) is the 2- to 6-leaf stage. That window is closing quickly for most canola crops. (Link to blackleg article at www.canolawatch.org.)

Seedling diseases: Some fields in Manitoba have been completely wiped out by seedling diseases. Many of those fields were canola on canola, where the seedling disease complex load could have been very high. Slow crop establishment due to excess moisture and cool conditions made the situation worse. No foliar sprays are available for seedling diseases, but growers should still dig and look at roots and stems to identify whether disease is the cause for weak plants. Click here for more information on what to look for.

Control cleavers, volunteer canola in cereals
Cereal crops in rotation provide canola growers with another opportunity to control cleavers, volunteer canola and other tough weeds to reduce the threat to next year's canola.

If you have cleavers in a field, remember than many cleavers have group-2 resistance. If using a group-2 product in cereals, consider a tank mix with an effective cleavers herbicide from another group.

Volunteer canola control limits clubroot build up. Growers in the clubroot zone need to control volunteer canola in non-canola crops. Volunteer canola provides clubroot a bridge for spore buildup and limits the effectiveness of the non-canola years in rotation to reduce the clubroot threat. This same practice also works for blackleg management.

Insect update
With rains across the Prairies, the insect threat is reduced - in general - but there are still hotspots for cutworms and flea beetles.

Flea beetles: Spraying continues in Manitoba where crops are advancing slowly due to excess rain and limited warmth. The flea beetle threat is over for most parts of Alberta and Saskatchewan.

Cutworms: Redbacked cutworms are still causing severe damage in southern Alberta. Some sprayed fields need to be reseeded. Click here for more on cutworm ID and management.

Grasshoppers: Spraying occurred last week in northern Alberta and around Meadow Lake, Sask., but rain has reduced grasshopper feeding in these areas.

Cabbage seedpod weevil: Entomologists anticipate a busy year for this pest in southern Alberta and southwest Saskatchewan. Scouting will be critical. Click here for more information and for Alberta Agriculture's latest weevil map. Alberta Agriculture is also asking agrologists to participate in the cabbage seedpod weevil reporting. Call 310-2777 (toll free) to provide sweep net counts to the reporting system.

Root maggots: Root maggot feeding is reported in southern Alberta where the pest has never been reported before. There are no sprays to control maggots. Click here for more information.

Gophers: Richardson ground squirrel damage can be confused with cutworm damage. Strychnine baits are available for gopher control. The emergency registration for 2% strychnine solution (for do-it-yourself baits) in Saskatchewan and Alberta ended earlier this month.

Read the Prairie Pest Monitoring Network's latest insect report: Prairie Pest Monitoring Network Jun13-17 update

Coming events
Manitoba Canola Growers Association is helping host a combine clinic with Enns Brothers June 28-30 in Portage la Prairie. CCC agronomy specialist Kristen Phillips will speak on June 28 and June 30. CCC crop production resource manager Derwyn Hammond will speak on June 29. Click here to register.

Controlled Traffic Farming Field Day: June 29 in Morrin, Alta., 1:00 to 4:30 p.m. Click here for more details.

ACPC Canola Crop Walk: June 29, Westlock, Alta. 10:00 a.m. to noon. Meet at the Viterra office in Westlock. Click here for more details.

ACPC Canola Crop Walk: June 29 in Barrhead, Alta. 1:30 to 3:30 p.m. Meet at the Viterra office in Barrhead. Click here for more details.

CCC Webinar: Sclerotinia Preview with Clint Jurke, CCC agronomy specialist. June 30 at 10:00 a.m. CDT. Click here to register.

Crop Diagnostic School in Carman, Manitoba is July 5-8 and July 11-15. Click here for more information. To register call 204-745-5663.

Farming Smarter diagnostic field school is July 5-7 in Lethbridge, Alta. Choose one day. Click here for more information and a registration form.

AAFC's Scott Field Day in Scott, Sask., is July 13. The morning tour is from 9:00 to 12:30 and the optional afternoon tour is 1:30 to 3:00. Canola topics include inputs to target high yield, seeding speed and its impact on emergence, and canola variety shatter resistance. For more information, contact Sherrilyn Phelps at 306-446-7475.

CCC Webinar: Sclerotinia Management in 2011 with Faye Dokken Bouchard, plant pathologist with Saskatchewan Ministry of Agriculture. July 14 at 10:00 a.m. CDT. Click here to register.

Combine Clinic. The Canola Council of Canada and Alberta Canola Producers Commission will host a Combine Clinic in Westlock, Alta., July 18 and 19. Click here to register.

The Canola Council of Canada's Convention is July 26-28 in Saskatoon. The theme is "Global Farmers. Global Markets." Click here for more information and to register.

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