Research
Grain conditioning is a widely used term that can be used to identify situations where either aeration or natural air drying is being utilized. Knowing the difference between aeration and natural air drying will aid in selecting aeration systems, equipment, and storage that will best suit your needs.
Published in Storage & Transport
Imagine yourself as a winter wheat kernel. You’re planted in the fall, germinate and grow a bit, then hibernate until spring when you start growing again. Meanwhile, fungus and insects are attacking your roots and shoots throughout the fall and spring. No wonder poor stand establishment is a major constraint for high-yielding winter wheat crops.  
Published in Cereals
Local Liberal MP Francis Scarpaleggia and Jean-Claude Poissant, Parliamentary Secretary for the Minister of Agriculture, announced $2.9 million in funding at a press conference for two McGill projects aimed at mitigating greenhouse gas emissions caused by water and fertilizer use in agriculture.
Published in Emerging Trends
Canola stubble has traditionally been the preferred stubble for winter wheat plantings because it can capture snow to insulate the overwintering wheat crop, improving winter survivability. However, some high-yielding canola hybrids have later maturities, presenting a challenge for seeding winter wheat at the optimum time.  
Published in Seeding/Planting
What I’d like to give you is a view from my previous careers working in Europe, New Zealand, and now Australia with regards to disease management. I’d like to give you a flavour of some of my impressions of disease management over the last 35 years with reference to getting the balance right with regard to the disease triangle and integrated disease management. 

Where are we in terms of integrated disease management (IDM)? What is IDM all about? Principally it’s about trying to make sure we use all the tools in the toolbox, integrating genetic resistance with chemical fungicides, cultural control and overall crop agronomy. When we sow the crop and how we look after it with nitrogen can profoundly affect how much disease pressure we’re under.

Getting it just right is never going to be easy. What’s happened in Australia? Before 2002, there wasn’t a huge amount of fungicide usage because it’s a much less responsive environment. Then we had an “exotic incursion.” Stripe rust came in from North America, probably on a grower’s boots. That changed the pendulum, from a dependence on genetic resistance to a reliance on fungicides, because, overnight, a huge proportion of all of the germplasm in Australia became susceptible to stripe rust.

Meanwhile in Europe, there was a totally different swing of the pendulum. It was inspired by a new set of varieties, in this case semi-dwarf varieties. With the new cultivars and more nitrogen, crops stayed greener for longer. Suddenly yields increased enormously in the ’70s. Higher yields and longer growing seasons in Europe drove growers to apply more and more fungicide. If you go to Europe now, it’s all about T1, T2 and T3 – Timing 1, Timing 2, Timing 3 with fungicides as a fixed part of crop agronomy. Up until 2005 in Europe, the pendulum had swung very much to the fungicide side of the IDM pendulum.

Slide 6
However, that’s all changed. In Europe, the profound driver for change has been fungicide resistance. Fungicide resistance influences everything that a European grower now does with fungicides. If there’s one thing that I think is really important to take on, it is that fungicide resistance – if it’s not affecting you now, it will be shortly unless you can moderate your use of fungicides.

What’s gradually happened over time is that we’ve got better products with greater activity, but at the same time fewer products based on limited modes of action. There are fewer products that are more and more environmentally benign, but at the same time at greater risk of resistance development. In other words, we’ve moved from multi-site fungicides that killed the fungus in many different ways to single-site fungicides that do less damage in the environment but actually are much more vulnerable to resistance.

Fungicide insensitivity and resistance
Fungicide insensitivity and resistance has occurred principally in two ways. In Europe in the late 1990s and early 2000s, strobilurins, such as pyraclostrobin and azoxystrobin, came along with the biggest media hype since glyphosate. However, after only three to four years, the pathogen causing powdery mildew and then Septoria tritici (now Zymoseptoria tritici) in wheat developed resistance to stobilurins, and that’s been a real challenge ever since. In two to three years, the strobilurins went from being the best products to control foliar diseases in broad acre cereals to products that wouldn’t work against Septoria, a disease that is widespread in northwest Europe. I think that’s when attitudes really changed and people started asking the question, “Is there a different way to control disease?”

Slide 16
We’re in our infancy with fungicide resistance issues in Australia. We can see it in the field with powdery mildew in barley. Our triazole fungicides such as Tilt (propiconazole), Folicur (tebuconazole), Proline (prothioconazole), Prosaro (prothioconazole and tebuconazole co-formulated) don’t work as effectively to control powdery mildew. With Septoria, we’re not yet seeing reduced activity in the field, but the samples are showing insensitivity in the laboratory, so there is increasing threat that we will see resistance to fungicides in the field. 

Europe and triazole use
What has happened in Europe with the triazoles over the last 20 years is that triazole fungicides have gradually become less effective against key diseases, firstly not working as effectively in the lab and then gradually being noted to be less effective in the field. That’s why with triazoles I think it’s important to talk about “fungicide insensitivity” and not “fungicide resistance.”

For example, it’s taken 20 years of exposing the Septoria pathogen population to the triazoles for them to become less effective. They still have activity but are now only 60 to 70 per cent effective when it used to be 90 to 100 per cent. So in Europe the triazoles and the strobilurins become less effective and ineffective for key diseases in a similar time period, but the triazoles had been gradually degrading in their effectiveness over time. 

Therefore with the terminology we use, I think it’s important to recognize we really have three basic modes of action that we use in broad acre cereal disease control – triazoles, strobilurins, and the new SDHIs [succinate dehydrogenase inhibitors].

With the triazoles I think it is probably more appropriate to call it “insensitivity” rather than resistance, since if you say to a grower, “It’s resistant,” the tendency is to think that it won’t work when in reality it is still partially effective.

With regard to the SDHIs, they’re not actually that new since the family of chemistry has been around for 40 years. But a new branch of SDHI chemistry is now taking Europe by storm, as the strobilurins now have less application because of resistance in key pathogens. But after only three years of commercial use with these new SDHIs, resistance is developing quickly in the net blotch and Septoria pathogens.

It’s really important to recognize that fungicide resistance is changing the way in which growers and advisors elsewhere in the world manage their cereal crops. In Australia, growers and advisors are just beginning on that resistance journey. You’ve already had some exposure in Canada to the fact that the strobilurins are at high risk of resistance development in the pathogen.  It begs the question, “What can you do about it?”

Click here for part two: The importance of multiple modes of action and linking pathology with crop physiology.
Published in Diseases
Benson Hill Biosystems, an agricultural technology company unlocking the genetic potential of plants through cloud biology, has announced a partnership with the University of Guelph to develop traits that increase canola yield as part of the Genome Canada Genomic Applications Partnership Program (GAPP). The GAPP, along with provincial co-funding from the Ontario Ministry of Research, Innovation and Science, will provide $2 million towards the $3.4 million project.

The GAPP funds research and development projects that address industry opportunities in order to accelerate the application of genomics-derived solutions and sustainable innovations that are beneficial to Canadians. Canola is a major driver of the Canadian economy representing $7.4 billion in farm cash receipts and over $9 billion in exports, primarily to China, Japan, Mexico and the United States. Canola also serves a critical role in our global food system. Seeds are crushed into a cooking oil that is one of the lowest in saturated fats, making it a popular choice for food services seeking to lower trans fats in their products. The remaining canola meal provides a high protein livestock feed.

Benson Hill, using its proprietary CropOS cognitive computational platform, has identified a portfolio of trait candidates demonstrated to improve photosynthesis, one of the most complex systems in plants that is responsible for all agriculture production. In collaboration with the University of Guelph, researchers will validate these and other trait candidates in canola for further testing and development.

Benson Hill's platform combines vast datasets and biological knowledge with big data analytics and scalable cloud-based computing – an intersection of disciplines known as cloud biology – to predict biological outcomes for any target crop using any genomics tool, from breeding to gene editing to transgenics. The ability to more accurately predict gene targets that are linked to certain phenotypic outcomes with CropOS enables Benson Hill to accelerate identification of promising trait candidates, reducing product development costs and increasing speed to market.
Published in Genetics/Traits
[Miss part one? Click here]
Importance of multiple modes of action

I’m horrified to hear that you can apply straight strobilurin fungicide to your crops, since there’s no other mode of action in the application to protect you from pathogen mutants that might be strobilurin resistant. If you went back to when the strobilurins were breaking down to Ascochyta in some of your pulse crops, it’s worth asking yourself, wouldn’t it have been better to have been using them in combination with other older multi-site fungicides in order to give the strobilurins a degree of protection? 

What’s now happening in Europe is that there’s a lot of dependence on the triazole fungicides since there is widespread resistance amongst a number of pathogens to strobilurins and increasingly to SDHIs. However it’s not the same with all pathogens. For example, the rusts – stripe rust, leaf rust – seem particularly stable. But with the necrotrophic diseases such as Septoria, such as net blotch, such as scald, populations are shifting. That stated, the triazoles remain the backbone of disease management programs all over the world.

It’s actually becoming more complicated for advisors in Europe. What’s happening is that different regions in Europe have different pathogen populations that are differentially susceptible to triazoles. What researchers are finding is that the triazole that works best in one area of Europe might not be the triazole that works best in another.

Now I know what you’re thinking: aren’t triazoles all from the same family of chemistry with the same mode of action? That’s where the resistance to these molecules is more complicated. For example, in one region, Folicur might not work very well on the Septoria pathogen, but a Tilt still does a reasonable job, depending on the history of fungicide use. Somewhere else in Europe, the exact reverse might be happening.

In Europe, they’ve set up a project called EuroWheat with 26 trials all across Europe examining triazole fungicides and their activity against key diseases, looking at not only what’s happening in the field in terms of foliar control, but then taking samples for lab analysis. It’s revealing that the pathogen is adapting in different regions differently, depending on what fungicides have been used, particularly the Septoria population. 

We are now beginning to see the same thing with Septoria in Australia. Some products that are effective on the mainland of Australia don’t work well in Tasmania. 

What can we do to protect fungicides going forward? We can minimize our use of them. Pick the best adapted, highest yielding, and most resistant varieties we can use. Such a choice might enable you to use just one fungicide application instead of two applications. In some parts of the world, there are guidelines advising using that active ingredient just once in a growing season. But probably the strongest message that comes out around the different regions of the world is the one about mixing different modes of action in cereal crops. 

So think about fungicides as part of that integrated disease management package – use them, but don’t overuse them. 

Across Europe at the moment, the new SDHIs are entering the market already mixed and formulated with a triazole in order to ensure the use of two modes of action in a fungicide application. “Make sure that you’re mixing different modes of action” is the strongest message that comes out of the scientific studies on fungicide resistance and it’s the one key take-home that I can give you. If you’re not mixing, ask why not.

There is one area that is important to clarify and that is with regard to fungicide rate and resistance. I don’t believe that there’s a lot of scientific evidence in the literature that suggests keeping fungicide rates high is a good anti-resistance strategy. Generally it is with herbicides, but I’m not sure that evidence exists for fungicides. Frank van den Bosch from Rothamsted in the U.K. did a literature search on 46 different fungicide studies and found there were more studies showing that increasing fungicide rate increased resistance selection pressure than the reverse. I think it’s more appropriate that we consider fungicide rate as an efficacy message, not a resistance message: i.e. what rate of fungicide is appropriate to obtain the best economic outcome. There are other things, like mixing our active ingredients with different modes of action, which are far more important in resistance management than considering fungicide rates.

Linking pathology with crop physiology
The other factor that is really important is linking our knowledge of pathology with crop physiology. Fungicides don’t only kill a disease, they keep plant leaves greener for longer, providing soil water is available to express the benefit of the disease free leaves. The upper leaves of the cereal crop canopy, particularly the top four, affect the ability of a plant to produce yield. In Australia, disease management strategies based on fungicides are particularly dependent on the presence of soil water to express the benefit of a fungicide both in terms of yield response and economic return. 

One of the things from Europe that I think they have right is that they talk all the time about “What are the key parts of the plant to protect from disease?” If you’re growing a cereal crop, what do the individual leaves on that cereal crop contribute to yield? That’s an incredibly important part of any strategy using a fungicide. We use fungicides to make money, not just control disease, and what’s been really good in Europe is actually characterizing which parts of the plant are best to protect from disease.

When it comes to thinking about fungicides, don’t only think about the disease. The time of disease onset in the crop will determine to which leaves fungicides are applied. In Europe, set development timings trigger the questions. “Do we have the disease? Are the conditions conducive for the disease? What’s this crop going to yield?” These are key questions that link the effect of the disease with the physiology of the crop.

Slide 29
slide 30
I think the key message when it comes to thinking about using fungicides as part of an integrated disease management package is to recognize that they’re not very effective at protecting tissue that’s not emerged at the time of application. Other than reducing overall inoculum in the crop, fungicides only directly protect the leaves and plant structures that are emerged at the time of application, so you need to target the most important leaves that contribute to yield.

The interaction of crop disease development and crop physiology is now a target for an Australian modelling team. In summary, it’s important to look at disease development and crop development together. 

I’d like to finish off with a reference to future developments. The Magnetic Induction Cycler (MIC) is about the size of a four-litre pail. From leaf samples using MIC, you can determine the genetic makeup of the pathogen population, determining not only the presence of genetic mutations that might affect fungicide performance but also the frequency of the population with that mutation. In the future this technology will assist the advisor in making the right product choice for individual paddocks. That technology moving forward could be linked with automated spore traps informing us when pathogen spores are moving into the paddock, their genetic makeup and how that’s going to affect product choice.

Lastly, I believe RNA interference technology has the potential to produce the next phase of environmentally-friendly fungicides. The technology is based on short segments of nucleotide that are absorbed into the plant and pathogen, and which can switch off the RNA messenger before it can synthesize the proteins for fungal development in that plant. It is very specific technology and offers some great potential for disease management in the future.
Published in Diseases
Three cutting-edge University of Guelph research projects in genomics –  one of today’s most rapidly developing and powerful areas of science and technology – have received $10.7 million in support to improve crop yields, animal health and welfare and food production.
Published in Corporate News
Droughts are a part of the Prairie climate and severe, prolonged droughts can put a strain on irrigation water supplies. Improvements can increase energy-use efficiencies, improve crop yields, and enhance the sustainability of water resources. Some of these improvements are also  eligible for current financial incentive programs.
Published in Irrigation
Blackleg is caused by two species of the pathogen. The major one is called Leptosphaeria maculans. The other one is a much less virulent species called Leptosphaeria biglobosa. For control of the disease, pathologists look at some of the weak links where we can apply most of the impact on the disease. The pathogen only survives on residues. If you don’t have a residue, it doesn’t survive well in the soil. That’s why rotation is important.

The pathogen produces a fruiting body in the spring called a pseudothecium or another type called a pycnidium. They produce spores that land on the cotyledons of canola. If you have insect damage from pests like flea beetles, the infection can be worse. With wounding, the pathogen can get into the cotyledon tissue even without moisture. From there the infection develops and you see the cankers at the base of the stem later on in the growing season.
Slide 4
Photo courtesy of Gary Peng.

There are three important things that can lead to an infection:
·      there’s residue to harbour the pathogen inoculum
·      you need to have early infection to get into the stem
·      insect damage may help the infection to occur more severely. 

The disease was very prevalent in the late ’80s, early ’90s. Then we introduced some resistant varieties in the early ’90s, which brought down the occurrence for many years. Partially that was resistance bred into varieties, but we also had three- or four-year rotations. That was a big part of the whole management effectiveness.

In the last five to six years, the disease incidence has been creeping back up to 20 to 25 per cent in Alberta and Manitoba, and about 10 per cent in Saskatchewan. However, the average severity remained below level 1 (light). Research by Sheau-Fang Hwang in Alberta indicates that in most years, this level of severity could result in a yield loss of about two to eight per cent on a susceptible variety. But from a trade perspective, our trading partners want to see the disease level trend going down.

Why the upward trend?
The first reason for an increase in blackleg incidence is likely the change of the pathogen population, which is adapting to the resistant varieties. The pathogen population may be becoming more virulent or with a greater proportion of virulent isolates in it. 

Plant breeders have used major gene resistance to control the disease. The resistant gene blocks the infection by the pathogen carrying the corresponding avirulence gene. For example, an Rlm3 resistant gene would block the pathogen with avirulence AvrLm3 gene (abbreviated to Av3). It might be like a lock-and-key, but for some reason, over time, the Av gene may change and the resistant gene may not be able to recognize it.

My colleague, Randy Kutcher, looked at the change in pathogen populations in 2007 when he looked at the avirulent gene prevalence on the Prairies. In his work looking at 800 isolates of L. maculans, the percentage of Av2 and Av6 genes were very high in the population, and the others at more moderate to low levels. Further work in 2010 and 2011 with Dilantha Fernando at the University of Manitoba found the picture had changed quite a bit. The presence of the Av3 and Av9 genes had decreased quite a bit, but at the same time Av7 seemed to be increasing quite a bit. That means the Rlm3 gene would be less likely to be effective across the Prairies because the Av3 gene had changed mostly to the virulent type. The Rlm3 gene was first introduced back in early 1990s and has been used for over 20 years.

Other research in Fernando’s lab also looked at what resistant genes are present in 206 varieties/breeding lines in Western Canada. The resistance gene that was predominantly found was Rlm3 in around 70 per cent of the varieties/breeding lines. There was also a bit of Rlm1 detected as well. Overall, the diversity of R genes is still quite limited in the germplasm tested. The important message is that Rlm3 is not going to remain effective on the Prairies because the corresponding Av3 gene is already fairly low in the pathogen population. 

However, when we looked at field data in Alberta and Manitoba, while the occurrence of other Av genes was high, disease levels ranged widely. This told us there was something else going on, which we called non-specific resistance in our varieties, although the effect was definitely less than the major gene resistance.

We further investigated this non-specific resistance in our varieties. We tested commercial varieties with a pathogen without a corresponding Av gene so any resistance observed would be due to non-specific gene resistance. Almost all the varieties had a slightly smaller amount of the disease on inoculated cotyledons than the susceptible Westar. At the same time, it’s a totally different kind of resistance reaction as opposed to the major gene resistance. It would not stop the infection completely – it just slowed it down a little bit, and on some varieties, substantially.

A further look at three of those varieties found the progress of plant mortality originated from cotyledon or petiole inoculation was somehow reduced, but varied between the varieties. Using a fluorescent protein gene labeled isolate, photography was able to show the reduced spread of the pathogen in the cotyledon compared to the susceptible Westar variety.

If you can slow down the movement from the cotyledon via the petiole into the stem, there may not be enough of the pathogen getting into the stem before the cotyledons drop off. This is one of the reasons that non-race-specific resistance works in some of those varieties we have.
SLIDE 22
Photo courtesy of Gary Peng.
Click here for part two: management strategies

This article is a summary of the presentation “Managing blackleg of canola in Western Canada,” delivered by Dr. Gary Peng, Agriculture and Agri-Food Canada, Saskatoon, at the Field Crop Disease Summit, Feb. 21-22, 2017. Click here to download the full presentation.

Don't forget to subscribe to our email newsletters so you're the first to know about current research in crop management.

Top Crop Manager's Herbicide Resistance Summit has been announced! Sign up today for early-bird pricing: https://www.weedsummit.ca/event/registration

Published in Diseases
A team of researchers from four American universities says the key to reducing harmful greenhouse gases (GHG) in the short term is more likely to be found on the dinner plate than at the gas pump.

The team, headed by Loma Linda University (LLU) researcher Helen Harwatt, PhD, suggests that one simple change in American eating habits would have a large impact on the environment: if Americans would eat beans instead of beef, the United States would immediately realize approximately 50 to 75 percent of its GHG reduction targets for the year 2020.

The researchers explained that beef cattle are the most GHG-intensive food to produce and that the production of legumes (beans, peas, etc.) results in one-fortieth the amount of GHGs as beef.

“Given the novelty, we would expect that the study will be useful in demonstrating just how much of an impact changes in food production can make and increase the utility of such options in climate-change policy,” Harwatt said.

In a 10-page paper released May 12, Harwatt and her colleagues noted that dietary alteration for climate change mitigation is currently a hot topic among policymakers, academics and members of society at large. The paper, titled “Substituting beans for beef as a contribution towards U.S. climate change targets,” can be found online.

In addition to reducing GHG, Harwatt and her team – which included Joan Sabate, MD, DrPH; Gidon Eshel, PhD; the late Sam Soret, PhD; and William Ripple, PhD – concluded that shifting from animal-sourced to plant-sourced foods could help avert global temperature rise.

Sabate, who serves as executive director of the Center for Nutrition, Healthy Lifestyle and Disease Prevention at LLU School of Public Health, said the findings are substantial.

“The nation could achieve more than half of its GHG reduction goals without imposing any new standards on automobiles or manufacturing,” Sabate said.

The study, which was conducted while Harwatt was an environmental nutrition research fellow at Loma Linda University, also found that beef production is an inefficient use of agricultural land. Substituting beans for beef would free up 42 percent of U.S. cropland currently under cultivation — a total of 1.65 million square kilometers or more than 400 million square acres, which is approximately 1.6 times the size of the state of California.

Harwatt applauds the fact that more than a third of American consumers are currently purchasing meat analogs: plant-based products that resemble animal foods in taste and texture. She says the trend suggests that animal-sourced meat is no longer a necessity.

“Given the scale of greenhouse gas reductions needed to avoid the worst impacts of climate change, are we prepared to eat beef analogs that look and taste like beef, but have a much lower climate impact?” she asks. “It looks like we’ll need to do this. The scale of the reductions in greenhouse gas emissions needed doesn’t allow us the luxury of ‘business as usual’ eating patterns.”
Published in Corporate News
World demand for food is growing and research and innovation will help Canadian farmers and food processors meet that demand. The Government of Canada is supporting science and innovation with key global partners to build the capacity necessary to take advantage of growth opportunities and create good, well-paying jobs.

As part of this effort, the Honourable Lawrence MacAulay, Minister of Agriculture and Agri-Food, today joined the Honourable Christian Schmidt, German Federal Minister for Food and Agriculture, in Prince Edward Island to announce that Canada and Germany will work closer together in four areas of agricultural research:
  • Sustainable agriculture and climate change, particularly in the areas of protecting soil and water and breeding crops that are more resistant to the effects of climate change;
  • Agri-food, including crop breeding for nutrition and health and reducing food waste and loss;
  • Sharing best management practices for knowledge and technology transfer to farmers and industry; and
  • Personnel exchange, including exchanges of scientists and students between Canada and Germany to build on opportunities for collaboration.
Canada and Germany enjoy close and friendly relations, reflected in their active cooperation on the international stage as well as their healthy economic and investment partnership. Germany has been a strong science partner with AAFC for over a decade, especially in the areas of crop development and animal health.

The Canada-European Union Comprehensive Economic and Trade Agreement (CETA) will give Canadian farmers, processors and exporters duty-free access to more than half a billion consumers across the EU, the world's largest import market for agriculture and agri-food. This agreement will help generate jobs and grow the middle-class.

Germany continues to be a significant trading partner for Canada and is growing in importance both as an export destination and as a source of imports.
Published in Corporate News
Dr. Kelly Turkington discusses considerations to spray a fungicide, recommendations for Fusarium head blight in cereals and how to get the most out of your cereal fungicide applications. 

Click here for the full summary of Dr. Turkington’s presentation.

Don't forget to subscribe to our email newsletters so you're the first to know about current research in crop management.

Top Crop Manager's Herbicide Resistance Summit has been announced! Sign up today for early-bird pricing: https://www.weedsummit.ca/event/registration
Published in Diseases

Research trials in the U.S., and more recently at the University of Saskatchewan, are proving what’s old is new again. In this case, the use of “old” herbicides such as Avadex, Fortress and Edge are making a comeback of sorts in a weed management system that’s been dubbed “herbicide layering.”

According to Clark Brenzil, who coined the term, herbicide layering is simply utilizing two to three herbicides in sequence to tackle tough-to-control weeds and to stave off weed resistance.

Indeed, herbicide tank mixtures and/or a program that utilizes a residual product in a sequential program are now the recommended practice for delayed herbicide resistance.

“It’s a good management tool for controlling some of those weeds that may not necessarily be that responsive to one herbicide,” Brenzil notes. “Wild oats and cleavers are two great examples of this.”

But even simply switching one herbicide out for another, ie. rotating herbicides, while perhaps delaying the onset of herbicide resistance, still results in selection pressure. Today, many in the industry are starting to stress the importance of using multiple modes of action and tank mixing.

“The extension message is to use multiple modes of action together in weed control programs,” says Mike Grenier, Canadian development manager with Gowan. “But it’s not only using tank mixes – it’s using products in sequence, for instance to look at the soil residual herbicides as part of this management program.”

The idea is simple: apply different modes of action within a season – layering – and rotate chemistries through the crop rotation. As it turns out, Avadex, Edge and Fortress herbicides fit very well into this strategy.

“In our scenario, you would have Group 8, Avadex or Fortress, being soil applied either in the fall or in the early spring followed with a post-emergent program during the growing season,” Grenier notes. “So in this case of Group 1 or Group 2 product use, Avadex is the pre-emergent layer providing resistance management against wild oats.”

In trials, Gowan maintains that Avadex and Fortress can provide about 90 per cent control of wild oat, while Edge (Group 3) provides 70 to 80 per cent suppression. “Then you have a post-emergent program working on a much lower level of [weed] population, so lower selection pressure. So now we have the control level approaching close to 100 per cent.”

Studies find an added bonus
Led by Christian Willenborg, weed scientists at the University of Saskatchewan (U of S) have been conducting research to determine if herbicide layering proves beneficial. “We have some good information in peas and some really good information in canola,” says Eric Johnson, U of S research assistant. “Graduate student Ian Epp’s research in canola showed some benefits, even with Roundup Ready canola, to be using clomazone pre-emergent to improve cleavers control.”

In the studies on cleavers weed control in canola, the researchers used three different modes of action – applying clomazone pre-emergent, then followed by either Clearfield, Roundup or Liberty tank mixed with quinclorac. “Even with the Roundup system, which is already pretty effective on cleavers, we found that using three different modes of action provided weed control benefits, and some yield benefits which totally surprised us,” Johnson notes. (See Fig. 1.)

The team also did studies on managing Group 2 resistant cleavers in field pea. “What we found was that if we put a pre-emergent down, that suppressed the cleavers somewhat. But then we came in and followed with a post-emergent, and we ended up with better than 80 per cent control.” (See Fig. 2.)

Going forward, the U of S is starting some work on managing Group 2-resistant wild mustard and Group 2-resistant kochia in lentil.

The big picture
Brenzil says herbicide layering has some merit for everyone. “What the U of S research has found is that if you have control taking place right at the point where the weed is germinating [with the pre-emergent], you’re going to get better yield response out of your crop, rather than waiting for the three- or four-leaf stage when there’s already been some competitive effect of that weed on that crop,” he notes.

“By having a soil active, even if it’s not doing a fantastic job of controlling the weeds, it’s suppressing the influence of those weeds on that crop, and you’re getting a bit of a yield bump by having herbicide in the soil along with your foliar product that’s coming a little later.”

An added bonus, Brenzil adds, is that by using a herbicide layering program, you’re making a pre-emptive strike against herbicide resistance. “It’s a good management tool for controlling some of those weeds that may not necessarily be that responsive to one herbicide for effective management, such as wild oats and cleavers.”

At the Herbicide Resistance Summit held March 2 in Saskatoon, Jason Norsworthy made a comment about the “treadmill” of using one weed chemistry and the very real threat of developing herbicide resistance as a result. Brenzil explains: “If you use one chemistry to death and then you allow your weed populations to get very high again, then you’re just starting from square one to select for the next Group that you’ll overuse, and so on and so on, until you paint yourself into a corner and there are no herbicide options left. At this point, the only management option left will be seeding the field to a forage crop and cut for hay until the seedbank is exhausted.”

With herbicide layering, “If you’ve got your soil active products on the ground, then you come in with your foliar and you’ve got a mix of two foliars that could still control that same weed – now you have three active in there of different families,” he adds. “You avoid that overuse and you don’t allow selection pressure to accumulate.”

 WTCJune16 Herbicide layering



This story originally appeared in the June 2016 issue of Top Crop Manager West.
Published in Herbicides
Crop rotation is an important tool for our first line of defence in Western Canada. From a pathologist’s perspective, a wheat-canola-wheat-canola rotation – a single year between host crops – is not long enough to realize one of the benefits of rotation and allow decomposition of any infested crop residue. 

Variety resistance is also an excellent tool. When you have a variety with good levels of resistance, you really don’t need to spray a fungicide. The problem is that in your field you’re facing a range of diseases and it’s been very difficult to get varieties that have good levels of resistance to absolutely every disease issue that you might have in that field. If you have a tight rotation, your variety may not have the package of resistance that you need and, as a consequence, you will start to rely on fungicides. 

We like to use the disease triangle to express what a disease is all about. It’s the result of a susceptible host, a favourable environment and sufficient quantities of a virulent pathogen. The key thing to remember is that what you do in terms of crop management practices will impact the interaction of those three factors and ultimately, the risk of disease. 
Disease triangle
The disease triangle. Source: Dr. Kelly Turkington

Interation of fungicides with variety resistance
At a trial in Melfort, Sask., three barley varieties rated susceptible (Sundre), intermediate (Chigwell) and with a good resistance package (Vivar) against net-form net blotch were sprayed with Twinline (metconazole + pyraclostrobin) fungicide at the flag-leaf stage. With no fungicide application, Sundre had just under 20 per cent leaf area diseased on the penultimate leaf, but there was very little disease on Chigwell and Vivar with or without a fungicide. With a fungicide, there was a dramatic reduction in disease with Sundre.

If we look at yield, Sundre went from around 115 bushels per acre (bu/ac) without a fungicide to 145 bu/ac with the fungicide application. Chigwell had a bit of a response to fungicide application, which may be because it has an intermediate level of resistance. Vivar’s response to fungicide was basically flat. So, if you’re using a resistant variety that is giving you the protection you need, you don’t need to worry about putting on a fungicide.

General knowledge on application timing
In terms of fungicide application timing in cereals for leaf disease, it is important to know where yield and grain fill comes from. The literature suggests the wheat ear (head) contributes about 22 per cent to yield, while the flag-leaf contributes about 40 to 45 per cent, and penultimate (leaf below the flag) contributes about 23 per cent. Those are the key plant tissues that you want to protect. 

In barley, the flag-leaf is less important because it tends to be quite small in some varieties. The literature for barley suggests the head contributes around 13 per cent, the flag-leaf stem 25 per cent, the flag-leaf nine per cent and the penultimate about 20 per cent.

Overall, if you’re looking at a target as far as protecting the plant tissues that are key for grain filling and yield, the upper canopy tissues in those cereal crops are going to be your target.

Pathogen characteristics
The characteristics of the pathogen can be very important when trying to improve your ability to manage plant diseases with a fungicide. A monocyclic pathogen has one cycle of spore production, host infection and disease development, so there’s a very specific target there. Fusarium head blight (FHB) is a monocyclic pathogen.

Polycyclic pathogens cycle on the living crop more than once per growing season. These are diseases like stripe rust, tan spot, Septoria, net blotch and scald. This cycle may mean you can’t rely on a single application and may need several applications to get the level of control you desire, especially with highly susceptible varieties and under favourable weather conditions.

Stripe rust is an example of a polycyclic pathogen. It can move from spring wheat onto winter wheat seedlings in the fall. If I were advising a producer, I would note the presence of stripe rust in the fall and then be out in the winter wheat field as soon as the crop started to re-grow in the spring to see if the stripe rust fungus had survived. The stripe rust pathogen can rapidly cycle on the wheat crop: spores released from pustules on infected leaves are carried by the wind to healthy leaf tissue where they germinate, produce hyphae, penetrate plant tissue and within seven to 14 days, you’ll have symptoms – including pustules that produce a new crop of spores. So, every seven to 14 days, stripe rust can cycle on the crop well before head emergence. Thus, later on, on those upper-canopy leaves, you may see symptoms of stripe rust that can cause significant concern, especially if the disease becomes established in the crop before flag-leaf to head emergence.

Fungicide insensitivity
What about pathogen adaptation to the active ingredients in fungicides? Pathogens with a high risk of adapting to the active ingredients in fungicides have the following characteristics: they have mixed reproduction, so they reproduce sexually as well as asexually; and they also have an outcrossing system of reproduction where with they have male and female isolates – or mating types, – so you need a male and female for sexual reproduction to occur.

Sexual reproduction where different mating types are needed has the potential to create more genetic variability in the fungal pathogen, which can then be selected for when applying a fungicide. The other important thing is high genetic and pathogenic diversity in that pathogen, which increases the risk that a pathogen will adapt.

An example of a pathogen at moderate to high risk of adaptation to either plant disease resistance or fungicide active ingredients is the net blotch pathogen. In a study funded by the Western Grains Research Foundation, Alireza Akhavan, a PhD student working at the University of Alberta, found high levels of genetic/pathogenic diversity in the net blotch pathogen. It also reproduced asexually as well as sexually and with mixed mating types. Using a laboratory assay, Alireza found a few isolates that were insensitive (resistant) to Tilt (propiconazole) and, in some cases, insensitive to Headline (pyraclostrobin).

Randy Kutcher at the University of Saskatchewan is also looking at the tan spot fungus and potential insensitivity in the tan spot population.

Shifts in the fungicide sensitivity of cereal pathogens have been recognized in Europe for some time now and there have also been reports of changes in North America.

For example, in February 2015, Chris Mundt and colleagues at Oregon State University put out a disease update notice (Oregon State University, Disease Update, February 20, 2015, Chris Mundt, Mike Flowers, Nicole Anderson and Clare Sullivan), stating that, based on surveys from 2014, there were indications some fields had Septoria resistance to strobilurin (Group 11) fungicides. They also reported resistance to triazoles (Group 3) was starting to build.

Their recommendation in that part of the Pacific Northwest was to only apply a fungicide for early-season leaf disease control when stripe rust was present, because the fungicides were still effective against stripe rust. They also recommended using a succinate dehydrogenase inhibitor (SDHI) fungicide (Group 7) once per year, and for growers who did so to combine it with either a strobilurin or perhaps a triazole.

Click here to see part two: managing the tools available, including fungicide application timing trials.


This article is a summary of the presentation “Getting the Most Out of Your Cereal Fungicide: A Western Canadian Perspective,” delivered by Dr. Kelly Turkington, Agriculture and Agri-Food Canada, Lacombe, Alta., at the Field Crop Disease Summit, Feb. 21-22, 2017. Click here to download the full presentation.

Don't forget to subscribe to our email newsletters so you're the first to know about current research in crop management.

Top Crop Manager's Herbicide Resistance Summit has been announced! Sign up today for early-bird pricing: https://www.weedsummit.ca/event/registration
Published in Diseases

Managing the tools available
Given that fungicides are an important component of their leaf disease management programs, farmers need to manage the fungicides we have by using products with more than one active ingredient and/or rotating the products they use. [Miss part one? Click here.]

When a susceptible variety is grown and weather conditions are very favourable, farmers may be concerned about early season leaf disease development. Rather than applying a fungicide with their herbicides, one option might be to look at a seed treatment and use xylem-mobile fungicides that will move from the seed up into the leaf tissue to provide some early season leaf protection.

These fungicides are mixed with other fungicides that give us good activity on some of the root rots, whether it’s Fusarium or Rhizoctonia or Pythium and so on. Ideally, one may want to use a seed treatment with different active ingredients versus foliar fungicides that may be used later on in the season, with one application of a triazole to give us some suppression of FHB and late-season leaf disease management. 

Using a seed treatment for early season leaf disease management is food for thought and may be a strategy to consider.

Nature of a fungicide influences risk of resistance
The nature of the fungicide also plays an important role in effectiveness. Some fungicides do very well in terms of particular plant pathogen groups versus other fungicides, so check the provincial crop protection guides to make sure you are choosing the right fungicide for the disease issues you are targeting. 

The nature of the fungicide also influences the risk of fungicide resistance. Fungicides with a very specific individual target (single site activity) within the pathogen are typically at higher risk versus actives that have multiple targets (multi-site activity).

Mobility within the plant also plays a role, as it influences the efficacy, persistence and period of activity. Mobility also influences application technology, so if the product is not systemic, it will be especially critical to use practices that ensure good coverage of the plant surface you are trying to protect.

Fungicide timing and leaf spot diseases
Fungicide application timing is important for cereal leaf spot management. From 2010 to 2012, we looked at the effect of fungicide timing on leaf spot diseases in barley at 13 sites. Specifically, we compared tank-mixing a fungicide with herbicide versus putting that fungicide on at the flag-leaf stage versus using a split application, a half rate earlier on and then coming in with either a half rate or a full rate of fungicide at flag-leaf emergence.

Overall, our results indicated the best leaf disease control and the highest yields were achieved where we put a fungicide on at the flag-leaf stage and where we did not delay the herbicide application and, thus, had early weed removal. 

Table 1: Yield and herbicide/fungicide treatment
slide 33
Turkington et al. 2015. The impact of fungicide and herbicide timing on foliar disease severity, and barley productivity and quality.               Can. J. Plant Sci. 95: 525–537.

Timing also a factor in stripe rust control
Another trial, led by Kutcher and Brian Beres with Agriculture and Agri-Food Canada in Lethbridge, Atla., and conducted in Lacombe, Alta., illustrated the importance of fungicide application timing for stripe rust control in winter wheat. The most effective application for AC Bellatrix, a susceptible variety, was in the spring at the flag-leaf stage. For Radiant, a variety with some resistance, there was no need for a fungicide.

As mentioned previously, seed treatments may be an option for early- to mid-season leaf disease management. Recently, we did a set of experiments – including at Melfort – looking at the interaction of variety, seed treatment and fungicide on net blotch on barley. In 2013, we simply used a seed treatment without a fungicide and reduced the level of disease to less than 10 per cent of the leaf area affected from 30 per cent in the untreated control. If you looked at Twinline foliar fungicide applied with no seed treatment, there was very good control. Where we combined seed treatment with foliar treatment, it really didn’t improve control.

Our best yield response was where we simply put Twinline on at the flag-leaf emergence stage, whether a seed treatment was used or not. Overall, if you look at work done by research groups across Western Canada, if you have the opportunity to choose a variety that has good levels of resistance to the disease spectrum you’re dealing with, that’s an excellent tool to manage disease and will help you to avoid a fungicide application. 

However, the varieties you want grow may not have a complete package of resistance to the diseases of concern. Thus, it will be important to scout fields at or just prior to flag-leaf emergence to assess disease risk and its potential impact to determine if a foliar fungicide application is required to protect key upper plant canopy tissues. 

FHB application timing
Currently the recommendation for FHB fungicide application is to spray when you’ve got 75 per cent of the heads out of the boot – that’s when you can start – to about when you have 50 per cent of the head showing anthers in the middle part of that head. The problem with starting at 75 per cent head emergence is that 25 per cent of the heads are still in the boot. Thus, given the nature of the fungicides that we use for FHB, applications at 75 per cent head emergence will not provide much, if any, benefit for those heads not yet emerged.

Recent research from the United States suggests we may have a wider window for application post head emergence to get the most out of that fungicide application. 

Trials from the U.S. looked at fungicide timing and effect on FHB disease rating and DON content with applications at the start of anthesis (when you first see yellow anthers emerging from the middle part of the wheat head) and then either two, four or six days following the start of anthesis. Overall, results suggested that even at four and six days after anthesis, control was as good as applications at anthesis, and in some cases may actually be slightly better.

The trend was similar with DON content.

I think, in terms of getting the most out of our fungicide application for FHB, we need to look at revising our target. Maybe going a little later is something to consider so you provide protection for all heads within the crop. However, growers are cautioned that they need to follow label recommendations and the pre-harvest intervals for the products they use.

Expectations for fungicides
In terms of expectations for fungicides, it’s important to be realistic. Fungicides can certainly be effective tools for some diseases, but it’s important to use them prudently and to manage those fungicides so they remain effective tools for you over the next 10, 15, 20 years. Timing can have a huge impact. Fungicide application also doesn’t mean a completely disease-free crop and, thus, it is important to leave some check strips so that you can adequately judge fungicide performance.

Overall, farmers are encouraged not to rely exclusively on fungicides as their only defence against plant disease. Try to use the other tools in the toolbox. The more tools you have, the broader your ability to control disease and other pest and crop management issues in your crop.  By using a range of tools, including crop rotations of at least two years between host crops, you’re going to prolong the effectiveness of tools such as disease resistance and fungicides into the future.


This article is a summary of the presentation “Getting the Most Out of Your Cereal Fungicide: A Western Canadian Perspective,” delivered by Dr. Kelly Turkington, Agriculture and Agri-Food Canada, Lacombe, Alta., at the Field Crop Disease Summit, Feb. 21-22, 2017. Click here to download the full presentation.

Don't forget to subscribe to our email newsletters so you're the first to know about current research in crop management.

Top Crop Manager's Herbicide Resistance Summit has been announced! Sign up today for early-bird pricing: https://www.weedsummit.ca/event/registration
Published in Diseases
Recent Alberta research shows that some wheat cultivars have a higher respose to more intensive agronomic management practices than others. This type of cultivar-specific information could help growers make more informed decisions on variety selection and management.
Published in Cereals
LET'S START WITH THE PAST...
In the past, disease management in field crops was largely based on major gene resistance and the use of fungicides.
Published in Diseases
Page 1 of 17

Subscription Centre

 
New Subscription
 
Already a Subscriber
 
Customer Service
 
View Digital Magazine

Most Popular

Marketplace