September 1, 2010
Sclerotinia infection, late-season hail and frost threats have growers wondering whether to swath early. Take time to make an informed decision.
Many canola fields are still a week away from 50% to 60% seed colour change — the ideal swathing stage — but damage from sclerotinia, hail or frost has some growers eager to get he crop cut. Early action is not usually the best for overall crop yield and quality. Step 1 before taking any action is to assess the level of damage.
Sclerotinia
In the case of sclerotinia stem rot, 2% of plants damaged can look like a lot from the road. But damage at these low levels is not enough to alter harvest plans. Growers are encouraged to swath as they normally would.
The key with sclerotinia infection is to determine where most of the yield will come from. If healthy plants will provide the most yield, then make harvest decisions that favour those healthy plants. Swathing at 50% to 60% seed-colour change is optimum for yield and quality.
If infected plants account for most of the yield potential, then swathing at 30% seed colour change may be more appropriate — as long as seeds in pods on branches and upper main stems are firm. Swathing early limits shelling of pods that are diseased but contain healthy seed. Sclerotinia fungus may continue to grow on swathed canola if conditions are wet, but seeds that have reached the firm green stage or later should still mature.
When swath-rolling diseased canola, do it lightly to tuck swath edges into the stubble. Light rolling limits pod shatter and reduces the spread of sclerotinia, which tends to move faster in compact swaths. If crop is heavily diseased, it may be preferable to avoid swath rolling altogether, particularly if the swath is heavy enough to settle into the stubble and does not appear at high risk for wind damage. Swath in the direction of prevailing winds.
Hail
Hail tends to damage top pods more than bottom pods. Since top pods are at later stages and typically have lower yield potential, don’t cut early to save these pods if seeds in these pods are still watery. Do what’s best for undamaged lower pods. That means swathing at 50% to 60% seed colour change.
An exception: If seeds in bruised top pods are firm when rolled between thumb and forefinger, then swathing immediately may save these top pods from shelling out. Seeds lower in the plant should be more advanced and also suitable for swathing.
Frost
Growers have two swath decision scenarios when it comes to frost:
- Should a grower swath canola when frost is in the forecast? 2) Should a grower swath immediately after a frost?
- Swathing canola in anticipation of frost only works when seeds are firm not watery, and when the swath has 3 good drying days before frost hits. This gives seed time to dry to below 20% moisture. At that point, frost damage to the seed will be minimal.
If light frost occurs before 3 good drying days, there is not enough time to have seed colour change. Frost can stop de-greening enzymes and lock in high green counts. Green seed levels can still be reduced after the frost event — but only if there’s enough time before the next frost and if there’s adequate moisture to rehydrate the seed.
When canola is fairly green and frost risk is only slight, there is more upside to leaving the crop standing. Swathing too early to avoid the risk of frost can often translate into yield and quality losses.
When to swath after a frost is more complicated. Assess fields one to 3 days after the frost, then make the harvest decision. Here are 4 situations and decision-making tips for each:
50% of the field has moderate to severe damage. Yield and quality will be significantly reduced. With severe damage, the canopy turns white, pods have a bleached and shrunken appearance, and seeds shrivel and turn white. If the remaining 50% of the field has light to minimal damage, swathing too early may further reduce yield and grade. Swathing when plants with minimal damage reach 50% to 60% seed colour change can allow the intact seed to continue to change colour and fill, improving both grade and yield. Anything severely damaged will likely shell out or be separated with the chaff or dockage.
More than 50-60% severely damaged. The crop will shell so it is best to swath to protect any viable seeds. Quality is likely to be poor anyway, so it is more important to protect as much yield as possible. If the grower decides to swath right away, the field in question should be one of the last fields combined to allow as much time as possible for green seed clearing.
Light to moderate damage in portions or throughout the field. Leave this for swathing at the proper stage. With moderate damage, pods will have white speckling on the outside and some seeds will turn brown and shrivel. However, pods remain reasonably intact and pliable and some seed remains green and turgid. Swathing when healthy seed is at 50% to 60% seed colour change gives healthy seed time to reach optimum yield and quality. Damaged seed will shrivel and blow out of the combine with the chaff or ending up as dockage. With moderate frost damage, growers will want to monitor the crop more closely than with other frost damage. If pods desiccate, they are prone to shattering, so consider swathing the whole field or just the affected areas if shattering losses could exceed gains from leaving the crop an extra day or two.
Some light damage in portions or throughout the field. Leave the crop and swath at the proper stage based on seed colour change of the healthy seed. Light damage may cause some seeds to turn “shoe polish” brown, but pods and most seeds generally remain intact and turgid. Swathing immediately after a light frost may result in higher economic and yield losses than if the crop were left alone.
For photos of severe, moderate and light frost damage, click here to download the Canola Council of Canada factsheet, “Early fall frost. Now what?”
For more information, contact a Canola Council of Canada agronomy specialist in your region:
Doug Moisey, North East and East Central Alberta, 780-645-9205
Troy Prosofsky, Southern Alberta, 403-332-1412
John Mayko, West Central Alberta, 780-764-2593
Erin Brock, Peace Region, 780-568-3326
Jim Bessel, North Central and North Eastern Saskatchewan, 306-373-6771
Tiffany Martinka, Eastern Saskatchewan, 306-231-3663
Clint Jurke, Western Saskatchewan, 306-821-2935
Derwyn Hammond, Manitoba Region, 204-729-9011
This media release is supported regionally by:
Alberta Canola Producers Commission; SaskCanola; Manitoba Canola Growers Association; Canola Council of Canada; Peace River Agriculture Development Fund; B.C. Ministry of Agriculture & Lands.
Tags: Canola, Canola Council of Canada, frost, hail, sclerotinia, seed colour, swath rolling, swathing stage, yield potential
The top nine of ’09 has a nice ring, but the big agricultural events of the year actually fall into just five broad categories. In agriculture, weather is usually a big story and it certainly was in ’09. The Saskatchewan crop had more lives than an alley cat. Despite drought, delayed maturity, the threat of frost and an extremely late harvest, the crop was above average overall and absolutely stellar in some regions. The flip side of the equation and number two on the list is the big drop in grain prices, particularly on the cereals. After record high prices in ’08, many crops have dropped back to disappointing levels. There are still some profitable crops, particularly lentils and canola, but the year ahead is uncertain. Profitability will likely depend on growing the right crops and having an astute marketing plan. The number 3 story of the year is the crop export barriers that have emerged. Europe has restricted our flax and China has restricted our canola exports. Even a visit by our Prime Minister wasn’t enough to change Chinese policy. Which commodity will be the next to run into a trade barrier? I’ll talk about number 4 and number 5 on the list on tomorrow’s commentary. I’m Kevin Hursh.
Tags: agriculture, Canola, cereals, delayed maturity, drought, export barriers, flax, frost, grain prices, late harvest, lentils, marketing plan, trade barrier, Weather
August is quickly approaching and it will be a frost watch month. In the most frost prone regions of the Saskatchewan grain belt, the first frost is typically by the end of August. For other locations, the average is some time during the first week of September. Areas with the longest frost-free days don’t typically get frost until the second week of September. Over the years, there have been a number of widespread frost events in August that have caused substantial crop damage. Last year was a particularly open fall. Can we be lucky two years in a row? Crops remain behind normal development and a number of areas flirted with frost earlier this month. Frost in August would be ugly. Many people correlate frost events with the full moon. The next full moon is August 5. In September, the full moon comes on the 4th. People who have examined the full moon / frost correlation scientifically claim that there is no relationship. However, a lot of folks are convinced that the two are linked. Whether or not moon phases play a role, the fate of the 2009 crop hinges on how many frost free days we can accumulate. I’m Kevin Hursh.
www.hursh.ca
Kevin Hursh, PAg, CAC
For more information visit www.dynagra.com
Tags: damage, frost, full moon, grain belt
This past week marked a turning point for Saskatchewan crop conditions. With major rainfall in most regions, dry conditions are no longer the biggest concern. In the provincial crop report released yesterday, only 14 per cent of cropland is rated as short for topsoil moisture. The areas rated as very short have all but been erased. In the driest regions, drought has already exacted a toll, but in most cases further crop damage has been halted. The biggest concern now is that crops are two to three weeks behind in many areas and last week saw some freezing temperatures. According to the crop report, the Kelvington area reported frost on two nights and the thermometer fell below zero for three nights in the LeRoy area. Frost was also reported in the Glaslyn and Pierceland areas. I received an email from a producer in the Regina area reporting frost on rooftops early Thursday morning. It isn’t supposed to freeze in July. There could be crops that have their seed set messed up by this touch of frost. In general though, the crop outlook has improved dramatically over the past couple weeks. I’m Kevin Hursh.
www.hursh.ca
Kevin Hursh, PAg, CAC
For your local weather forcast visit www.dynagra.com
Tags: crop conditions, Dynagra, frost, improved, positive, rainfall
A trio of problems is threatening the Saskatchewan crop – drought, frost and delayed development. Delayed development is a concern in most regions. In lots of fields, you have to get down on your hands and knees and maybe brush away some soil to find emerging plants. Some early-seeded crop has decent growth, but overall development is no where near normal. Usually by this point in June, post-emergent herbicide application is well underway. Not this year. Producers are still waiting for crops and weeds to develop. Many areas have received frost. Every year, there is frost concern somewhere and talk of reseeding. This spring, the frost damage is much more widespread and the reseeding is more than just talk. Crops in all parts of the province will need rapid development to beat the first fall frost. On top of the cold spring, west central Saskatchewan is facing a serious drought with other areas not far behind. It may seem a bit premature in June to predict how the Saskatchewan crop is going to turn out, but the odds right now are for below average production with below average quality. I’m Kevin Hursh.
www.hursh.ca
Kevin Hursh, PAg, CAC
Tags: delayed development, drought, frost, herbicide, post emergent
Many producers were unable to do a pre-seed burn-off so it is critical to maximize efficiency with the first in-crop pass. The first step is scouting to determine weed species present and staging. Some growers are noticing that the grassy weeds are present and need to be controlled, whereas broadleaf weeds are slower to emerge. While research has shown that sequential applications are rarely economical, in this situation, it may be practical to split apply herbicides. For instance in the Liberty-tolerant system, it may be better to apply a graminicide earlier (for control of wild oats and volunteer cereals that are ahead of the crop) and wait to apply Liberty when more broadleaf weeds have emerged, rather than trying to rely on a single pass with a tank mix. This is especially true in drier areas where those early weeds are competing for precious moisture.
Frost can interfere with herbicide performance. After a light frost, it is important to wait until temperatures rebound in the middle of the day before spraying. After a heavier frost that will cause damage, wait a few days for plants to recover before spraying. Maximize crop safety and weed control - crops will tolerate the herbicide and weeds will take in the herbicide when actively growing.
Canola Council
Tags: frost, herbicide performance, in-crop, scouting, spraying
Snow, freezing temperatures on four to five nights and in some areas, heavy frosts (as low as minus 7°C), occurred across the Prairies last week. This may prompt canola growers to consider reseeding. However, resist the urge to reseed immediately, as recovery may turn out to be better than expected, especially if seed has not yet germinated or the young seedlings have become acclimated to the cold. Snow may actually be beneficial as it can act like a blanket and insulate the crop, especially if the snow cover came prior to the most severe freezing temperatures. If the seed has not germinated and is still hard/firm, not soft/mushy, it will likely survive and just needs warmer conditions. After several days of near freezing temperatures, emerging canola that is near the surface or that emerged under cool conditions will undergo a gradual hardening process, allowing the plants to withstand freezing temperatures without serious damage. Studies have shown that early-seeded canola seedlings that had undergone hardening could withstand minus 8 to minus 12°C temperatures. Cooler conditions result in plants that are slower growing, producing smaller cells that have a higher concentration of soluble substances that make them more resistant to frost damage. This hardening off process helps defend plants against the chain of plant gene activities set off by cold weather that produce or degrade the proteins that protect plant cells. Wait at least three to five days or longer depending on growing conditions before making any decisions on canola crops. The desired plant population is approximately 10 plants/ft2 but lower plant populations (as 3 to 4 plants/ft2 in some circumstances) can be adequate, especially in late-emerging stands. It will likely be better to leave a thinner stand (provided it is unitform) than take the risk of late reseeding because maturity/early fall frost becomes a concern.
For more information on assessing frost damage in canola see the following link: https://canola-council.merchantsecure.com/canola_resources/product37.aspx
Tags: Canola, frost, insulate, reseeding, snow
Recent snowfall and frost in Alberta and some other parts of the Prairies may be prompting canola growers to consider reseeding, but the Canola Council of Canada (CCC) urges producers to wait a few days or longer to assess the damage.
“Resist the urge to immediately reseed, as recovery may turn out to be better than expected, especially if seed has not yet germinated or the young seedlings have become acclimated to the cold,” advises CCC senior agronomist Doug Moisey. “The snow cover will act like a blanket in some respects and may protect the crop, especially if the snow cover came prior to the severe freezing temperatures, although the plants will be under stress.”
“If the seed that has not germinated is still hard/firm, not soft/mushy, it likely will be fine.”
After several days of near freezing temperatures, emerging canola that is near the surface or that emerged under cool conditions will undergo a gradual hardening process, allowing the plants to withstand freezing temperatures without serious damage.
Studies have shown that early-seeded canola seedlings that had undergone hardening could withstand minus 8 to minus 12°C temperatures. That’s because cooler conditions result in plants that are slower growing, producing smaller cells that have a higher concentration of soluble substances that make them more resistant to frost damage. This hardening off process helps defend plants against the chain of plant gene activities set off by cold weather that produce or degrade the proteins that protect plant cells.
Growers should wait at least 3-5 days or longer depending on growing conditions to assess their canola crops, says Moisey.
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For more information in your area, contact:
Derwyn Hammond, Manitoba Region, 204-729-9011
Jim Bessel, North Central and North Eastern Saskatchewan, 306-373-6771
Tiffany Gutzke, Eastern Saskatchewan, 306-231-3663
Doug Moisey, East Central Alberta and Northwestern Saskatchewan, 780-645-9205
Matthew Stanford, Southern Alberta and Southwestern Saskatchewan, 403-345-4852
John Mayko, West Central Alberta, 780-764-2593
Erin Brock, Peace Region, 780-568-3326
Tags: emergant, frost, germination, prairies, re seeding, snow
