In Alberta, clubroot is showing up a lot at field entrances (in 90 per cent of the infected fields, according to one study), which suggests equipment is the main culprit in its spread.

It’s a similar pattern in Saskatchewan — field entrances and in areas where water pools temporarily around grain bins and also access routes to power lines or oil sites.

But in Manitoba, clubroot is showing up in low spots or along drainages in fields, said Bruce Gossen, a research scientist with Agriculture and Agri-Food Canada.

“This probably reflects the fact that, at this point, most of the spores are coming in as airborne spores, and being washed into and concentrated in some areas, where you are getting hot spots of infection,” said Gossen.

As the disease becomes more established in more fields the transmission pattern will likely be more similar to Alberta, when it will be transported on equipment and vehicles moving from field to field.

But in the meanwhile, producers might be able to help slow its spread.

“Most of the strategies for reducing spore concentrations are extremely expensive to do on a field basis, but if you catch it early there’s an opportunity for growers to minimize the movement of soil out of those patches and then fix the patch in place,” said Gossen.

Clubroot is spreading fast in Alberta and Saskatchewan, largely because a heavily infected canola field can produce quadrillions of spores.

He urged the farmers in his audience to remember that no single approach is effective on its own.

“You can’t just use a resistant cultivar and call it a day,” said Gossen.

There are some good resistant canola varieties available that work well until there is high disease pressure which is beginning to break down resistance.

“Breeders are developing new resistant cultivars, but 12 new pathotypes have been identified so far, so it’s hard for the breeders to keep up with the range of pathogens out there,” said Gossen.

Seed treatments are ineffective against clubroot, but there are some alternatives to genetic resistance that look promising, such as liming, fumigation and solarization.

But they are expensive and still at the experimental stage.

Generally, clubroot favours acidic soils (with a pH lower than 6.5). A pH of 7.2 or higher inhibits spore germination and disease development, but not always.

“When you look at it under controlled conditions, the relationship, although strong, in terms of disease is not immutable, so even at a very high pH like eight, when the conditions are good in terms of moisture and temperature, infection still happens at a high rate,” said Gossen.

Experiments have been done in Alberta, with surface applications of hydrated lime to try and raise pH. It does appear to work, but at $1,000 per ton, liming is not cheap and is only feasible for small patches.

Gossen’s research hasn’t found much connection between soil type or organic matter content in terms of clubroot development, but compaction is a big factor.

“Where soil is compacted, moisture stays in the soil surface a lot longer and lets the zoospores swim,” he said. “In a field situation, sandy soil will drain faster and so likely is a little bit less at risk but even in a dry area, a sandy soil can get a three-day rain and you don’t even need three days for this pathogen to get going.”

Top tips for clubroot management

Federal researcher Bruce Gossen has seven tips for dealing with a small patch of clubroot in a field:

• Identify and mark the infested area with GPS co-ordinates and also mark a bigger area in every direction because it’s not likely the only patch in the field.
• Don’t dig and transport plants away from the area as this will potentially spread hundreds of billions of spores. Remove plants, getting as much of the root as possible and burn the roots at the spot.
• Keep out of that field until you have dealt with the patch and avoid spreading it — for example, do not cultivate.
• Treat with lime — aim for a target pH of 7.5, which is about seven tons of lime per acre.
• Get a grass growing that has lots of roots to keep the soil in place and is less conducive to the disease. There is some evidence that the roots stimulate germination of resting spores and because of the life cycle on grasses it will bring down the number of resting spores in the area.
• Leave in grass until the levels are reduced and you have a resistant canola cultivar that you can go back in with. If you don’t use a resistant cultivar, you will end up with more disease.
• Put in a new field exit and a sanitation zone to clean equipment before leaving the field to protect other fields.

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Growth regulators are designed to limit the internode elongation of plants by reducing the extension of the cells — in other words, to shorten the growth habit of the crop. This strengthens the straw, which helps improve standability.

Growth regulators have, to this point, been used more extensively in Canada’s horticultural industry for applications such as keeping ornamental nursery stock short and bushy rather than tall and leggy, to better suit the tastes and requirements of home gardeners.

The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) is now studying adapting the use of growth regulators for use in wheat. After only one year of trials the results are still inconclusive but encouraging, says Peter Johnson, a cereal crop specialist with OMAFRA who is heading up the research. “What I will say is that if the growth regulator works properly it will only shorten the crop about three to four inches at the most or about the length of the head,” he says. “It doesn’t always shorten the crop, but what is intriguing is that even when it doesn’t shorten the crop, it will thicken the straw. So you can have a crop that doesn’t look like you have done anything to it and it will still stand better.”

Johnson doesn’t expect growth regulators to be the complete answer to the problem of lodging. If there is excessive nitrogen the crop will lodge even with the use of growth regulators, but Johnson does feel that there is lots of scope to play around with application rates to help reduce lodging potential in most situations. Future trials will focus on fine tuning growth regulator applications with nitrogen rates to achieve optimum results under different conditions.

Johnson doesn’t see any impediment to using these types of products under prairie growing conditions. “These products are used in Finland and other northern climates, so as far as latitude and the shortness of the growing season is concerned, I doubt that would have any impact on the effectiveness of the product for use in Western Canada,” says Johnson.

Many different generic brands of growth regulators are available in Europe and elsewhere, but for his trials Johnson is using the two brands which are currently approved for use in Canada. The first product, Cycocel (also known as CCC) has chlormequat chloride as its active ingredient and is currently registered for use on wheat, but with varietal limitations on the label. The other product is Ethrel, which contains the active ingredient ethephon.

Ideally, Cycocel is applied just as the growing point is above the ground or when the plant has around five leaves. Nighttime temperatures need to be above zero C. It can be applied later, up to the second node stage, but will be less effective. Ethrel, on the other hand, is applied later — at the flag leaf stage, but conditions cannot be excessively warm, as when the temperature exceeds 28 C there is a significant risk of phytotoxicity in the plant.

The high cost

A big impediment to widespread use of growth regulators at the moment is cost. To use Cycocel at its recommended one litre per acre rate currently costs around $38 to $40 an acre, making it cost prohibitive, even at the half litre rate which Johnson believes would be acceptable under Ontario conditions most of the time. In Europe the same product competes with many generic versions and costs around $5 per acre. Johnson believes that once generic versions become commercially available in Canada, the product will become more attractive for farmers.

“The patent is off chlormequat chloride and therefore generic products could be brought in and labelled here. There is at least one and perhaps two companies working on that very thing,” says Johnson. “These companies are looking at the cereal market rather than the horticultural market because it is a much larger market. There is a pretty good chance that the price per acre will drop dramatically if they are successful in getting those products here and labelled for use here.”

Increased combine speed

A small number of Ontario farmers are already using growth regulators on their wheat for another reason, says Johnson. “We do have growers who swear that if you use the growth regulator the crop will combine easier, just because it has that resilience and it doesn’t break up as much in the combine, so you have a little less challenge separating the grain from the straw,” he says. “I haven’t done any work to support that from a scientific standpoint but I do know some growers who say that is the main reason they use a growth regulator, because they can combine more acres per hour.”

So, although there is still much fine tuning to be done, some Ontario farmers are already using growth regulators and interest is growing. “We have gone from a standard N rate of 90 to 100 lbs. to 120 to 130 lbs., and are looking at going to 150 lbs. N/ac,” says Johnson. “We’re trying to push wheat production here in Ontario, just to keep it somewhat economically competitive with corn and soybeans. And the only way to do that is to increase N rates and as soon as you increase N rates then lodging becomes an issue. So farmers here are tremendously interested in these products.” †

The post Try growth regulators to prevent lodging appeared first on Alberta Farmer Express.

Other recent challenges for farmers include increasing amounts of Group 2 herbicide-resistant cleavers and wild mustard in pulse crops. Group 1- and 2-resistant wild oats in cereal crops continue to have significant economic impacts for some growers.

Fungicide resistance

As fungicide costs have come down it’s more economical to use them. Fungicide use in wheat has been fairly high for a number of years, as farmers spray to control diseases like fusarium head blight and rust.

As the use of chemical controls increases, is resistance in crop varieties under greater pressure? “There are some concerns in using fungicides but variety resistance should not be overcome any quicker with fungicide use,” says Brent McCallum, a plant pathologist at Agriculture and Agri-Food Canada in Winnipeg. “The concerns with continual fungicide use are that the pathogens will develop resistance or tolerance to the fungicide and the environmental effects of fungicides, since they are broad spectrum and control all fungi (beneficial and harmful) in the crop, and to some extent the soil.”

Application of fungicides can, in some cases, hamper research work. As most wheat fields in Manitoba are sprayed with fungicides, there are limited samples that researchers can collect to test for virulence. Samples are more easily available in Saskatchewan, where fungicide use is lower and from other sources like nurseries and experimental trials. “Monitoring is very important,” says McCallum. “This year we found virulence to Lr21 for the first time in Canada. Lr21 is in many of our wheat cultivars and many lines in development, so knowing that it is less effective is important information for the future.”

Pre-mixed fungicides

New products are coming to the marketplace all the time, including pre-mixes, which promise better efficacy by combining different modes of action in one, ready-to-use product. But the theory behind pre-mixes, especially fungicides, is somewhat confused, says Bruce Gossen, a plant pathologist with AAFC at Saskatoon. “The accepted best practice for managing fungicide risk includes use of pre-mixes, which are expected to substantially reduce the risk of fungicide insensitivity,” he says. “But some of the modelling that is being done doesn’t actually substantiate that approach. How effective it’s going to be in the long term is still being assessed.”

In the field, pre-mixed fungicides offer advantages to growers in Western Canada, where farmers have not used a large amount of fungicides over many acres for a long time. These fungicides often mix one product, which may be at a high risk for insensitivity but that has a lot of activity against a particular pathogen, with another product that may not be as effective against that pathogen, but which has a much lower risk of insensitivity. This makes the odds of getting resistance to both products very low.

“From a grower’s standpoint, these fungicide mixes are a smart way to deal with the issue,” says Gossen. “We don’t recommend that growers apply the same mix year after year on a field. But if they are rotating fungicides and crops and including mixes as part of the approach, the odds of having trouble with fungicide sensitivity are much reduced.”

Farmers should, however, be cautious about seeing any one product as a solution in and of itself. “The lessons learned with herbicide-resistant weeds should be applicable to the evolution of fungicide-resistant pathogens,” says McCallum. “In some places, such as Europe, where fungicide use is high, they have seen the appearance of fungicide-resistant, or tolerant, or less-sensitive pathogens, so we should watch for that here as well.”

Farmers should not rely on just fungicides, but also make use of the genetic resistance in the host plant and McCallum advises farmers to regularly consult their provincial seed guides, which list the levels of resistance of each cultivar to various diseases. These can change over time if a pathogen population evolves increased virulence on a particular cultivar.

“The combination of improved genetic resistance and fungicide application has proven effective in controlling diseases such as fusarium head blight,” says McCallum. “We don’t want to get into a situation in which we rely on fungicides and neglect genetic resistance. In some cases in Europe the reliance on fungicides has lead to a decline in genetic resistance to diseases such as rust. Recent legislation in Europe has mandated a reduction in fungicide use and now they are trying to develop genetic resistance, which can be a hard task.”

Knowing what’s in the jug is just as important for pre-mixed herbicides, which aren’t always designed to manage resistance. “In many cases the pre-mixes are just to broaden the spectrum of weed control and it may not do anything for resistance management,” says Hugh Beckie, a research scientist with AAFC in Saskatoon. “You have to look at what are the active ingredients in these pre-mixes and what are your key target weeds that you want to try and protect against resistance and see if it’s going to be effective or not.”

Management practices

Good management practices are still essential to help maintain long term resistance in crop varieties. “I tell growers that 95 per cent of their disease management is done before they ever plant the crop,” says Gossen.

It all begins with rotation, of both crops and chemicals, to try and help keep resistance strong. “One of the things we are concerned about is the short crop rotations occurring over large parts of the Prairies, which is the wheat/canola rotation,” says Randy Kutcher, associate professor of cereal and flax pathology at the Crop Development Centre, University of Saskatchewan. “Instead of having a longer rotation with more species and more opportunities to use different products, we are targeting the same disease in the same crop perhaps every two years or in some cases every year, which increases the risk that pathogens will adapt to the fungicide and the variety, or both.”

A rotation of three to five different crops drastically reduces the risk of resistance developing to herbicides or fungicides. It also helps to break up the disease cycle, as most diseases (with the exception of sclerotinia and a few root diseases) are specific to one crop type. For example, rusts infect cereals but not pulses; blackleg will affect canola but not cereals or pulses. “If you can break up the cycle and let any diseased residue deteriorate before you plant the next crop it will certainly help prevent adaptation of the pathogen to particular fungicides or varieties. This applies to residue-borne diseases, such as blackleg of canola and many of the leaf spot diseases of cereals,” says Kutcher.

Canola, which has woody stems, does take a lot longer to break down, which is why a three-to five- year gap between canola plantings is advantageous. “We are growing close to 19 million acres of canola across the Prairies,” says Kutcher. “And although shorter rotations make total sense from a business case, from a biological perspective it’s a risky thing to do.”

No canola varieties are effectively resistant to sclerotinia, which also affects other broadleaf crops that may be used in rotation, making it a difficult disease to deal with. As a result, producers in the moister areas of the Prairies routinely spray for sclerotinia in every canola crop. Kutcher recommends that, in this case, producers use a different product each year, so that if they spray in year one, by the time they come back to use that product again, hopefully six or eight years later, most of the pathogen that was sprayed using the original product will be gone. “Sclerotinia bodies can last about five years in the soil, so if they are spraying for sclerotinia with the same product every second year there is much more risk that the fungus will become insensitive to that product,” says Kutcher. “Using a different product, and with two actives in the jug will help negate that somewhat.”

Farmers can also make sure they use clean seed and a seed treatment. “If someone else has a fungus in their field that is resistant to a fungicide and you buy that seed, you could be transferring the problem to your farm,” says Kutcher. “So that’s why it’s a good idea to start with good, clean, certified seed and use a seed treatment to try and get rid of the pathogen on the seed.”

Managing resistance

Sound agronomy and a long- term approach is always important in managing resistance, says Beckie, especially when it comes to weed populations. “Whatever farmers can do to give the crop a competitive advantage to suppress weeds will be helpful,” he says “Whether that be increasing your cereal crop seeding rate, banding or point injecting fertilizer or including competitive crops or varieties in your rotation.”

Farmers also tend to forget about trying to minimize weed seed spread during harvest, says Beckie. Cleaning equipment often will help reduce weed transmission from one field to another.

“All of these things together do have an impact but it does take a longer-term viewpoint,” says Beckie. “Unfortunately, with the lack of alternative herbicides, it will be inevitable that we will see more resistance in the future.” †

The post Plan Rotations to Avoid Fungicide and Herbicide Resistance appeared first on Alberta Farmer Express.

“One thing that became very clear this year is that having something green and growing in the spring takes moisture out of the soil,” says Oliver Joslin, who farms near Rossburn, Manitoba. “I saw for myself how much better the soil is for having something growing on it as opposed to nothing at all.”

And that applies even if it’s only weeds. Joslin made a post-harvest kill of thistles on some of his land in the fall of 2010, but with the very wet spring in 2011 he wasn’t able to get the tractor into other areas. However, he was able to seed the unsprayed areas where the volunteers had already begun to grow.

Although 2011’s fickle weather was tough on yields in many places, it’s provided a unique opportunity to really understand what happens under both conditions.

Seed blend

Joslin experimented with a polycrop for the first time on 25 acres and was one of two farmers who hosted summer field tours organized by the Manitoba Forage Council, Manitoba Grazing Clubs and Ducks Unlimited Canada in association with local holistic management clubs.

Polycrops are a mix of different crops sown together to improve soil health. They can be used for silage or grazing and depending on the blend help improve soil fertility and structure in order to lessen their dependence on farm inputs. Initial work shows that plant diversity improved emergence and production of the polycrops. In addition, customized blends were created to address various soil issues.

For example, use of radish and turnip helped break down soil compaction and till layers. Polycrops in Manitoba are being explored to improve native pasture by providing complementary grazing, improve cattle gain and lengthen the grazing season.

Multiple uses

“Cover crops improve soil health, increase organic matter and encourage microorganism activity that enhances nutrient cycling and the availability of nutrients for plant growth,” says Mike Thiele, Manitoba Grazing Club co-ordinator.

Polycrops can be used as greenfeed, be grazed or left for ground cover to help trap snow and maintain rainfall on the land instead of losing it to leaching, evaporation or runoff. They are also very useful for building organic matter in the soil, and the diversity of species means that the crop is more resilient to changing weather conditions. The mix can be adapted to suit specific growing areas and soil types, making them a versatile addition to the grazing plan.

On his Rossburn-area farm, Joslin’s polycrop blend included 30 lbs of oats, 50 lbs of peas, one lb of turnips, one lb of forage radish and one lb of hairy vetch seeded directly into oat stubble the first weekend in June. No fertilizer was added apart from a starter mix at seeding. The crop received a light rainfall after seeding but then remained dry until late summer. Despite low growing-season moisture, the crop was lush and weeds were few.

Aside from providing good ground cover and using subsurface moisture, the polycrop also produced a valuable forage stand. Joslin’s option included strip grazing the field in the fall, baling the crop as feed, or harvesting what he estimated would be about 3,500 lbs of silage per acre.

Cost for the seed was around $250 for the 25 acres, which is fairly reasonable, says Thiele. “A polycrop doesn’t have to be expensive,” he says, adding overall input costs shouldn’t exceed $20 to $25 an acre and the seed mix can actually be any combination of seed a farmer may have lying around.

“The more diversity the better,” says Thiele. “The idea is to have lots of different species so the odds of getting good germination of some of them are better whatever the conditions.”

Several benefits

 Diversity of plant species also helps prevent insect problems by discouraging the over-predominance of any one type of pest that typically occurs in a monoculture. Diverse root types help improve the water infiltration ability of soils.
 
 “Using turnips and radishes in the mix, for example, is useful as each have different root types and they each occupy a different part of the soil profile,” says Thiele. “So it helps to break up hardpan and allow moisture to penetrate and move through the soil profile.” The root vegetables stay in the ground and decompose to also help build organic matter.
 
The concept of seeding a mixed blend polycrop has crept into Manitoba from North Dakota, says Ducks Unlimited agronomist Ken Gross. Gabe Brown, a beef producer near Bismarck North Dakota, developed the concept of a polycrop as part of his strategy to save his mixed farming operation after hail wiped out his grain crops in the mid-90s.

Brown says that when his lender pulled the ripcord after annual crops failed, he decided he might survive financially without cash cropping so he embarked on a wild venture to harvest everything with his cattle. His farm made a recovery that is nothing short of miraculous, now involving a rotation that encompasses crops purely for grazing, crops taken for silage or hay, and a few crops for grain again.

Brown’s grazing techniques are also highly advanced, using cells for super-efficient "harvesting" by the cattle, as well as stimulating growth of the perennials species used. The response of his soils and crop yields has been phenomenal, yet Brown experiments with scads of “crazy” new ideas all the time. “We try to fail on at least one thing every year,” he says.

Gross says while the concept of a diverse mixed stand makes sense, the challenge may be to find a combination of crops that do well in the Manitoba climate. “One advantage they have in North Dakota is a longer growing season than we have here in Manitoba,” says Gross. “Some of the cooler season crops like annual cereals do well, but some other species such as hairy vetch are warm season crops that may not work every year.”

The crop blend can be designed to address specific objectives on each farm. It can be tailored to use up excessive moisture, include plants with root systems that help break up hardpan or compaction layers, help fix nitrogen in the soil, and contribute to improving soil organic matter.

While all this is happening to benefit soil structure and productivity, the crops also produce a valuable forage crop. “The main interest of Ducks Unlimited is similar to most ranchers — water and grass,” says Gross.
“We are supportive of any practices that help make farmers more productive and sustainable and the concept of polycrops might be one more strategy that fits in their overall farm management.”

Article courtesy of Manitoba Forage Council and Ducks Unlimited Canada

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