Diseases
Across most of south-central and southeastern Ontario, there’s been 50 to 100 per cent more rain than normal,” says Scott Banks, a cropping systems specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA). “It’s certainly been a challenging year. There isn’t really a silver lining to all this rain: no crops like being so wet. But growers have experienced tough years before. Outside of controlling the weather, there isn’t a whole lot they can do other than trying to minimize the issues and crossing their fingers for a warm, open fall.”
Published in Seeding/Planting
From planting and digging potatoes to observing insects feeding on plants to learning about coloured spuds, Agriculture and Agri-Food Canada’s (AAFC) Fredericton Research and Development Centre opened its doors and wowed visitors with plenty to see and do. Despite the rain, AAFC staff welcomed nearly 400 people for an open house held on August 19th in celebration of the 150th anniversary of the department. Curious visitors spent time touring research plots, visiting labs and learning about the science that goes into developing better potatoes.

AAFC’s researchers shared their knowledge of genetics, entomology, agronomy, hydrology and measuring carbon dioxide. Josée Owen, associate director of research, development and technology transfer at the centre, says there’s a lot of new science emerging in potato research and the open house was a great opportunity to show the public the diversity of the work that goes into creating a more resilient crop. Disciplines such as bioinformatics computing and agr-environmental resilience are areas the centre is focusing on to develop potatoes that are more efficient, adaptable and environmentally-friendly. Owen said she was “very pleased to see such enthusiasm from the public in learning about the science that goes into potato research and how scientists are addressing industry challenges."
Published in Corporate News
Researchers led by Ahmad Fakhoury, associate professor of plant pathology and fungal genetics at Southern Illinois University Carbondale analyzed soil samples from 45 soybean fields in Illinois, Iowa and Minnesota. They collected samples from symptomatic patches in fields and from adjacent areas where soybean sudden death syndrome (SDS) foliar symptoms did not develop. Fakhoury’s team compared microbial populations in the “healthy” and “diseased” soil to correlate the presence incidence and severity of SDS. 
Published in Diseases
Building off several research studies over the last decade, research scientist Cecil Vera at Agriculture and Agri-Food Canada (AAFC) in Melfort, Sask., wanted to narrow down the fungicide application window for control of pasmo disease in flax and investigate the effectiveness of fungicides in reducing the impacts of the disease. Graduate student Tonima (Trisha) Islam summarized the results of the three-year study that ran from 2014 through 2016 under the supervision of Randy Kutcher, an associate professor in the department of plant sciences at the University of Saskatchewan.

“Not much research has been done on the effect of fungicides on the pasmo disease in Saskatchewan and Alberta,” Islam says. “I think these new findings will help flax growers understand how to control the disease.”

The research compared three fungicides and three application timings to measure the effect of pasmo disease severity, crop maturity, seed yield, thousand seed weight and test weight of CDC Bethune flax. Trial locations were at Vegreville, Alta., Melfort and Saskatoon, Sask., and Brandon, Man. The fungicides Headline EC (pyraclostrobin), Priaxor (pyraclostrobin + fluxapyroxad) and Xemium (fluxapyroxad) were applied; currently only Headline and Priaxor are registered on flax for control of pasmo.

Fungicide application timing was at early flower (BBCH 61) and mid-flower (BBCH 65), and a dual application was made at both early and mid-flower. Applications were compared to a control without fungicide application.

Islam found all fungicides reduced disease severity, but Xemium was the least effective. With respect to timing, fungicide application at the early stage was the least effective. There was no difference in disease severity between the mid-flower application stage and the dual fungicide application.

Priaxor had significantly higher yield compared to the control and other fungicides. Priaxor increased seed yield approximately 25 per cent (2,295 kilograms per hectare, or kg/ha) compared to the control (1,822 kg/ha), followed by Headline at 19 per cent (2,172 kg/ha) and Xemium at 18 per cent (2,159 kg/ha). No significant difference was observed between Headline and Xemium.

Effect of the Xemium (fluxapyroxad), Headline (pyraclostrobin) and Priaxor (pyraclostrobin + fluxapyroxad) on seed yield of flax at Brandon, Melfort, Saskatoon and Vegreville in 2014, 2015 and 2016
Pasmo chartSource: Islam et al., University of Saskatchewan.

However, the Priaxor treatment delayed maturity by five days, which could present a risk to seed quality in some years. The dual fungicide application also delayed maturity by five days. This delay in maturity may be a result of the effectiveness of the fungicide treatment – pasmo often results in premature ripening and earlier harvests. Earlier seeding may help to offset the delayed maturity.

wtcm25.4 plotsPriaxor increased seed yield approximately 25 per cent compare to the control.

Timing of application and the impact on seed yield was also significant compared to the control. Applying fungicide at both the early and mid-flower stages increased seed yield approximately 25 per cent (2,273 kg/ha) compared to the control (1,822 kg/ha), followed by mid-flower timing at 21 per cent (2,210 kg/ha) and early flower timing at 17 per cent (2,143 kg/ha). Yield at the mid-flower application timing was not significantly different from either the dual application or the early flower application, but there was a significant difference between early and dual timings.

Effects of fungicide application timings (early, mid and both stages) on seed yield of flax at Brandon, Melfort, Saskatoon and Vegreville in 2014, 2015 and 2016Pasmo chart 2Source: Islam et al., University of Saskatchewan.

In terms of thousand seed weight and test weight – proxies for seed quality – the mid-flower and dual treatment increased TKW and test weight.

Even though the dual application provided the highest yield, economically, the net return on a second application may not make sense. “With the yield increases we have seen in Trisha’s trial and my previous experience in Melfort in the 2000s, I think two applications would rarely, if ever, be economically beneficial, based on current yields and prices for the fungicide and flax,” Kutcher says.

Making the application decision
Basing a fungicide application on the presence of the disease is difficult. Vera says that while there are cases in which pasmo may appear early in the season, in most instances the evidence of pasmo symptoms appear later in the season, and by then, it would be too late to spray.

“Usually, conditions for pasmo infection differ from year to year and from location to location, which was quite evident in this study. I think the best strategy would be to protect the crop with the best and most economical recommendations and hope for good results,” Vera says.

This means a farmer should base their decision to spray a fungicide on environmental conditions coupled with previous experience with pasmo, flax frequency in the rotation and proximity to adjacent flax stubble.

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Published in Fungicides
While driving through the Salaberry-de-Valleyfield region in southern Quebec in mid-June, John McCart, president of the Quebec Farmers’ Association, noticed farms in the area were sitting empty, void of the crops that should have been planted the month before. 
Published in Corporate News
Resistant soybean varieties have helped farmers manage soybean cyst nematodes (SCN) for decades. Almost all SCN-resistant soybean varieties possess the same resistance genes, from a soybean breeding line called PI88788.

Recently, Iowa State researchers analyzed 25 years of data, from tens of thousands of four-row variety evaluation research plots, to look for long-term trends. The results, published in the scientific journal Plant Health Progress, showed a breakdown of resistance in SCN-resistant varieties. 

“This is an alarming trend and sets the stage for even greater yield loss from SCN in the future,” Gred Tylka, Iowa State University nematologist said. | READ MORE
Published in Diseases
Anita Brûlé-Babel discusses the economic losses associated with Fusarium, how resistance ratings are developed for seed guides and utilizing risk maps. 

Click here for the full summary of Brûlé-Babel's presentation.

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Published in Corporate News
Wheat is an important crop in Canada, representing nine per cent of total farm cash receipts in 2015, and averaging 16 per cent of crop receipts in Canada from 2011 to 2015, according to Statistics Canada. And Fusarium head blight caused by Fusarium graminearum is the most important wheat disease. Fusarium head blight also infects barley and is a problem in malt barley production. With increasing corn acreage in Manitoba, there is a greater incidence of ear rot caused by F. graminearum as well.

The first and worst epidemic in Manitoba was in 1993. Since then, Fusarium has slowly spread to new areas across the Prairies, and by 2008, it was commonly found in the Dark Brown and Black soil zones in all three Prairie provinces.

There has been an emergence of new Fusarium populations and shifts in existing populations since 2000. A possible cause is the accidental introduction of isolates from one area to another, or one country to another.

Fusarium head blight is a concern because of the mycotoxins that can be produced by the pathogens. Fusarium graminearum produces two toxicologically relevant groups of mycotoxins. These mycotoxins have major impacts on swine feeding, resulting in poor feed intake and poor growth. Swine feed intake is reduced 7.5 per cent for every one part per million (ppm) of deoxynivalenol (DON) found in the diet.

The first mycotoxin group is the Trichothercens, which includes DON and the acetylated derivatives such as 15-ADON and 3-ADON. The DON mycotoxin is very stable during storage, milling, processing and cooking and doesn’t degrade at high temperatures. The other mycotoxin group in the Trichothercens is Nivalenol (NIV) caused by F. cerealis. It is not a virulent but is 10 times more toxic than DON. This group could become a concern and we don’t have a good monitoring system for NIV.

The second major mycotoxin group is Zearalenone and its derivatives.

The current issues with Fusarium mycotoxins in the Canadian feed supply is that Fusarium pressure in Canada is widespread and may be increasing because of wet seasons that promote the disease. There is also the additional risk of mycotoxin exposure from new feed ingredients such as distiller’s dried grains with solubles (DDGS) that are corn or wheat based. There is an increased risk in livestock feed with DDGS, since DON concentrates in in DDGS by approximately three times.

There appears to be a shift in the pathogen population with 3-ADON becoming more prevalent. This is a concern since 3-ADON makes significantly more toxin that is also more toxic. The LD50 for swine with 15-ADON is 113 milligrams per kilogram (mg/kg) while it is 49 mg/kg for 3-ADON. Analysis conducted by Ward et al in 2008 found that 3-ADON was found in six per cent of Alberta samples tested, 11 per cent of Saskatchewan samples, and 39 per cent of Manitoba samples.

We have looked at genetic chemotyping of DON isolates. On winter wheat, we found 3-ADON accounted for 82.4 per cent of F. graminearum isolates in Winnipeg and 84.6 per cent in Carman, Man. At Melfort, Sask., 3-ADON accounted for 100 per cent of the DON population. Canadian Grain Commission samples of CWRS wheat in 2015 indicated a shift to 3-ADON in the Black and Dark Brown soils zones.

This shift to a greater prevalence of 3-ADON brings new issues in managing the disease because of the increased virulence of 3-ADON. And because of the higher toxin production, there will be new issues at the elevator, in DDGS feeding and at the trade level because of potential downgrading.

The accidental discovery of NIV producing isolates in winter wheat at Carman by Chami Amarasinghe at the University of Manitoba is also a concern. Five of 132 Fusarium isolates were found to be NIV. In these isolates, 65 per cent were identified as 3-ADON, 31 per cent 15-ADON, and four per cent NIV. The presence of NIV is a concern, since it is 10 times more toxic to livestock than DON.

The identification of NIV is a concern because F. cerealis and F. graminearum are very similar and difficult to distinguish from each other. Until 2012, NIV had only been detected in a few barley samples in Canadian grain. However, testing for NIV in Canada is not routinely conducted at grain mills or elevators.

Amarasinghe also investigated the possibility of masked mycotoxins in our grains. These mycotoxins are masked because their structure has been changed in the plant. This process occurs when plants detoxify DON by converting it to DON-3-Glucosides (D3G). Masked mycotoxins are also known as modified mycotoxins and can’t be detected by conventional chemical analysis. However the danger is that gut microbes in livestock digestive systems may be able to convert D3G back to DON.

Findings from Amarasinghe’s research showed Canadian spring wheat cultivars produced D3G upon Fusarium infection, and there were significant differences among wheat cultivars. The susceptible cultivars showed a lower D3G to DON ratio (less D3G content) compared to the moderately resistant/intermediate cultivars. She found the level of resistance might have an effect on the production of D3G during the infection.

Looking into the future, Canadian wheat production may be at greater risk of Fusarium infections. An increase of 3-ADON, the potential for NIV to establish, and masked mycotoxins in our grain may be food safety issues. Additionally, with climate change, there is a possible threat of an increase in mycotoxins or having new mycotoxins such as the new NX-2 population establish.

Historically, in Canada we have seen shifts in the past. In the Great Lakes area, we saw a shift from ZEN to DON in the mid-70s, similar to the shift from 15-ADON to 3-ADON on the Prairies in the 2000s.

There are now some wheat varieties that have resistance to Fusarium in winter wheat and Canadian Spring wheat. Other classes also have varieties that are moderately resistant to Fusarium as well. These are important and should be considered as management tools.

This article is a summary of the presentation "War of the titans: The battle for supremacy in wheat-fusarium interactions," delivered by Dr. Dilantha Fernando, University of Manitoba, at the Field Crop Disease Summit, Feb. 21-22 in Saskatoon. Click here to download the full presentation.

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Published in Diseases
I work in Manitoba and we’ve been dealing with Fusarium head blight (FHB) for the last 25 years. In the 1990s, Manitoba started seeing severe infections. Those of you who are from Saskatchewan and Alberta, over the last two to three years, have definitely seen what it can be like when conditions are correct for Fusarium head blight infection.
Published in Diseases
In Ontario, soybean seedling diseases and root rots are the second most important yield limiting diseases, and this year is no different. Cool soil temperatures along with early rains in parts of Essex and Niagara resulted in a large number of soybean fields needing to be replanted and recent significant rainfall has had a negative impact on soybeans in many areas.
Published in Agronomy
In 2016, we conducted field surveys for root rot of pea and lentil in Alberta and Saskatchewan. In Alberta we surveyed 27 lentil and 89 pea fields during flowering, and 67 lentil and 68 pea fields in Saskatchewan.
Published in Diseases
Alberta’s wheat farmers can now add a Fusarium Head Blight (FHB) risk tool to their agronomy toolbox, improving their ability to make well-informed decisions related to FHB disease management. The risk tool was developed in a partnership between the Alberta Wheat Commission and Alberta Climate Information Service (ACIS) with expert support from researchers based at Agriculture and Forestry (AF) and Agriculture and Agri-Food Canada (AAFC).
Published in Corporate News
Most soybean and canola acres have been planted across the province, the majority of corn acres are in the V3 to V5 range, and much of the winter wheat crop has progressed beyond the post-flowering stage, according to the latest field report from the Ontario Ministry of Agriculture, Food and Rural Affairs. Here's the breakdown by crop, below. 

Cereals

A large majority of the winter wheat crop has progressed beyond the post-flowering stage, and spraying for Fusarium head blight protection has been completed in many regions. Stripe rust is reported to be advancing in some areas in fields that did not receive a fungicide application. Significant yield loss can occur in cases where disease pressure is very high. Fields that received a T1 or T2 herbicide application are reported to be still holding disease pressure back well. True armyworm has been observed in some fields, but not at levels that have required control. Growers are encouraged to watch for head clipping feeding. Clover stands in winter wheat look excellent.

Corn
A large majority of the crop ranges from the V3-V5 stages. In general, growers and agronomists in many areas report that plant stands and crops look great. The exception is some localized, heavier textured soil regions where planting conditions of earlier planted corn may have been pushed, and replanting is occurring. Sidedressing has started or is well underway in many areas. OMAFRA recently completed it’s annual PSNT measurement survey from June 5-6. Average soil nitrate concentrations were 8.0 ppm which is lower than the 11-12 ppm range that has been observed over the past 5 years, suggesting N mineralization may be delayed from the cooler spring. The last year when PSNT survey values were in this range was 2011. With the recent warm weather, growers and applicators are reminded to check corn herbicide labels for maximum temperature restrictions. Of particular note, spraying of hormonal herbicides (ie. dicamba) should be avoided when temperatures are expected to be above 25 C during or after application.

Soybeans
With the exception of a few localized pockets where wet conditions have prevailed and planting continues, the majority of the soybean crop has been planted. The majority of the crop is in the 1-2 trifoliate stage. While stands look reasonable in many cases, some replanting continues in areas which received heavy rainfalls after planting where crusting was evident (particularly on fine textured soils), as well as areas where seedcorn maggot pressure was high and reduced populations. A uniform population as low as 100,000 plants per acre is still considered to provide good yield potential. Planting conditions have been reported to be good for late planted or replanted soybeans. Bean leaf beetles and soybean aphids have been observed in some fields, but at very low populations where control is not warranted. If soybeans are to be rolled after planting, rolling should occur at the 1st to 2nd trifoliate stage where plants are no longer brittle and susceptible to snapping, and ideally in the heat of the day when plants are flaccid. High stand losses can occur when plants are crisp and susceptible to snapping between the emergence and the 1st trifoliate stage. When in doubt, check plants after starting to roll and evaluate the stand for snapped plants which will no longer be viable.

Forages
Growers are reporting excellent yields for first cut hay. First cut hay timed for higher quality has neared completion in many regions. In general, there has been a good weather window for first cut in most parts of the province for both haylage/silage and dry hay, and harvest progressed quickly as a result.

Canola
While a small amount of canola planting was still being reported in some areas up until the end of last week, most planting is complete and the majority of crop across most growing regions is in the 3-4 leaf stage. Swede midge emergence was being reported as early as late May, and was occurring prior to Canola emergence in some fields. Growers are encouraged to place and monitor Swede Midge traps. The control threshold is 20 adults across all traps in a field, and has been met in some fields this spring. Flea beetle pressure has been apparent in some fields, with some control being warranted. As the crop progresses beyond the 3-4 leaf stage, Canola is generally able to keep ahead of feeding. While Cabbage Seed Pod weevil has been observed in some fields, it is not typically an issue until pod set starts.

Edible Beans
Edible bean planting is reported to be nearly complete with an estimated 95 per cent of intended acres planted. Planting progressed very quickly once started, with a large amount of crop planted in a relatively narrow window. Planting conditions have been reported to be good.
Published in Corporate News
Cereals
Current weather conditions are ideal for fusarium head blight development in winter wheat. Many wheat fields in Southwestern Ontario have applied a T3 fungicide to reduce their risk particularly if they are growing a FHB susceptible variety. T3 fungicide applications further east will begin this week and continuing into next week for Eastern Ontario. A number of fields saw increased stripe rust pressure over the weekend. Growers with fields that were a few days away from a T3 application opted to wait and spray for both stripe rust and fusarium at the T3 timing. Some fields received an early heading fungicide application if they were a week or more away from a T3 fungicide application and growing a stripe rust susceptible variety to reduce the impact from stripe rust. Those fields will then receive a second fungicide application at pollination for protection against fusarium if needed. There have been reports of leaf tip necrosis starting on the flag leaf and moving down in fields. This leaf tip necrosis is likely associated with a specific or group of disease resistant genes and is the plant’s response to the presence of disease such as stripe rust. The yield impact from this is minimal.

Early spring cereal fields are at tillering and continue to look good. All weed control applications should be wrapping up shortly.

Corn
Corn planting is essentially now complete. With the exception of corn silage or some growers in long season regions, most unplanted fields will now likely be switched to soybeans. If corn herbicides have been applied but corn could not be planted, work with your herbicide provider to determine next best cropping steps. Overall corn is progressing well with a large amount of crop at the 2-3 leaf growth stage, with early planted corn beyond that. Minimal corn replants have been reported to date. Some sidedressing is now underway. There have been reports of black cutworm and slug feeding in a number of fields as a result of delayed crop planting and emergence and cool, wet weather conditions. There have also been reports of corn turning purple or white as a result of stress but those fields are expected to grow out of this.

OMAFRA Field Crop staff began tracking soil nitrate levels at a number of sites across the province the first week of May. Initial results suggest that soil nitrate levels are lower this year compared to previous years. Conventional PSNT timing sampling is being completed this week. Results will be posted at Weathercentral.ca under “Corn – GFO Nitrogen Research” as they are made available.

Soybeans
Soybean planting is 80 per cent completed across the province with some areas further behind compared to previous years due to significant rainfall this spring. The crop ranges from the hook stage to unifoliate growth stage. There continues to be weed challenges in a number of fields that did not receive a pre-plant burndown. Weed control during the early stages of soybean growth is critical. When making herbicide spray decisions pay attention to the growth stage of the weed as well as the growth stage of the soybeans.

There have been damage reports and replants particularly in Lambton, Essex, Niagara and Haldimand counties where they have received large amounts of rainfall and crusting became an issue. When doing plant population assessments a stand with 100,000 uniform plants per acre should not be considered for replanting. Research has shown that 100,000 plants per acre has a 98 per cent yield potential on most soil types.

On heavy clay soils 110,000-120,000 plants per acre are necessary for maximum yield potential. Rolling fields after the soybeans have fully emerged compared to rolling immediately after seeding helps alleviate stand losses due to crusting. Rolling can be up done up to the 1st trifoliate stage. There have been reports of seed corn maggot feeding in a number of regions due to the cool, wet weather. Fields planted without Class 12 insecticides that have sufficient stand loss due to certain soil insects including seedcorn maggot may warrant the completion of Inspection of Crop Pest Assessment by a professional pest advisor. If stand loss thresholds for the Class 12 regulations are reached, Class 12 insecticides can be purchased for that farm property. Contact a Professional Pest Advisor and refer here for more information. Bean leaf beetle feeding has also been reported in Essex County. Fields planted with fungicide-only seed should be scouted during the early seedling stages. Spray is warranted if 16 adult beetles per 30 cm of row are found on VC to V2 stage soybeans. If plants are clipped off at the stem, control is warranted if adults are still present and actively feeding.

Forages
First-cut alfalfa has begun in many areas with excellent yields being reported to date. Growers who applied some early season N to forage stands are reporting significant yield boosts. Alfalfa weevil and potato leafhoppers have been present in some areas. 

Canola
Canola emergence has been good to date; however, crop advancement has been slow particularly in northern Ontario. The earliest planted fields are at the 4 leaf stage. Growers in the Timiskaming area are already catching swede midge at this time and are likely going to have to spray sooner than anticipated. Swede midge has also been caught in the Shelburne area but has not yet reached thresholds. Due to the later planted crop and swede midge emergence this year it is anticipated that swede midge feeding will be a significant challenge. There have also been reports of high flea beetle pressure in some fields. 

Edible Beans
Due to the excessive moisture in many areas, edible bean planting is approximately 15 per cent complete. It is expected that the remaining acres will be planted later this week once conditions dry up.
Published in Corporate News
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
[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
Dr. Gary Peng discusses the key management strategies for blackleg in canola and how farmers will benefit from the new resistant gene labelling. 

Click here for the full summary of Dr. Peng's presentation. 

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Published in Diseases
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
Management strategies
The Canola Council of Canada is proposing a risk assessment chart. If you have a four-year rotation, likely your risk of having blackleg is very low. We know it’s effective, but I realize it isn’t always easy to implement. [Miss part one? Click here]

Scouting is important because it gives you a sense of your risk situation. There is an easy procedure that can be used to assess risk. After swathing, pull 50 plants, cut the stems at the base of the plant where blackleg develops and assess the damage to the stem. Use the pictorial guide I developed to assess the level of disease. If you don’t have any disease or very light disease, your variety might still be holding fairly well as long as you continue with longer crop rotation. But if you have an R-rated variety with a much higher disease level than you expected, your variety may not be holding up.

If you do want to switch varieties, try to rotate to another major resistance gene. We currently don’t have enough public information from seed companies to know what their resistance sources are. The Canola Council of Canada has proposed a new resistance labelling system to show the resistance gene labelling. It is voluntary and may start in 2018.   
Slide 25
Photo courtesy of Gary Peng.

If you don’t have any issues or major blackleg damage, there’s no urgency for you to switch between resistance groups right away, but it’s always a good practice to rotate them if you know the R genes. We understand 90 per cent of growers would rotate among the different varieties today mostly for weed management options. There is a similar principle in rotating varieties for disease management.

I want to also stress that we have quite a diverse pathogen population on the Prairies. In reality, over 90 races have been detected. That means with every known resistance gene, there is a different virulent isolate out there that would be able to overcome the resistance right away. We really need to consider, if we have different R genes available, rotation of those R genes. And we also need to maintain the non-race-specific resistance, which has been serving us relatively well.

What about fungicides?
Research on various fungicide products and application timings has been conducted. One involved 17 station years across the Prairies. We used four fungicide products, mostly the strobilurins and a triazole, and a combination of both active ingredients. We looked at applications at the two- to four-leaf stage, the bolting stage, and an application at both stages.  We also compared a susceptible variety with a resistant and a moderately resistant variety.

When we put all the data from 17 station years together, the early application of a strobilurin fungicide reduced the disease severity and also increased yield quite significantly compared to the non-treated check. The average disease severity was around about 1.5. The later application did not work, which makes sense because the key stage of infection is the cotyledon. 

We further looked at the data and divided it into two scenarios: those fields with much lower disease levels of around a 0.5 severity rating, and those with a disease severity of about 2.5. In the fields with low disease severity, the fungicide application did not provide any yield benefit. Where disease severity was about 2.5, a fungicide application at the two- to four-leaf stage reduced the disease severity significantly and also increased yield by seven bushels per acre compared to the non-treated check. 

However, these results were on Westar – a susceptible variety that was used to show the worst case when an R/MR variety is losing resistance. We looked at R/MR canola varieties at the 17 site years and found none of the fungicide applications were effective in providing a yield advantage (also indicating that the R/MR varieties have stronger tolerance to blackleg impact). That means if you have a certain level of resistance in your variety, in most cases the fungicide application would not provide a substantial yield benefit.

Where a fungicide treatment might come in is if the varieties you have been using are starting to show signs of an increased amount of blackleg. You should scout crops and assess the level of disease development over time. Also consider the length of the crop rotation and other risk factors outlined by the Canola Council of Canada. If you feel you are at high risk, an early application at the two- to four-leaf stage may be warranted.
Risk chart


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

Small planes have been flying over local farms and taking aerial photos for decades. Now, individual farmers are able to get an aerial view of a field using a small remote-controlled drone equipped with a camera.

But Agriculture and Agri-Food Canada (AAFC) has been receiving information from a far more sophisticated data collection network for at least the past 30 years, according to Leander Campbell.

Campbell, a geographer who specializes in geomatics, works as a remote sensing specialist with the Earth Observation team at AAFC. He says most of his work is on the AAFC Annual Space-Based Crop Inventory. He gets his data in the form of imagery from satellites and uses it to produce an accurate national crop map.

“The crop map, the one I work on, is at a 30 metre resolution so each pixel is a 30 metre by 30 metre square. It covers all of Canada,” he explains. Campbell adds one of the crops mapped in year one of the crop inventory in 2009 was soybeans. Since then, the data has shown how the crop is spreading west and north on the Prairies.
WTCM30.1 MB soybean 2009 2012
Campbell extracted only the soybean fields (in yellow) from Manitoba crop maps for the years 2009 and 2012.
Photo courtesy of Leander Campbell, AAFC.

The network Campbell gets his data from consists of several international satellites. The American satellite Landsat-8 provides optical data to create crop maps anyone can download. In addition to these data, Campbell’s team also uses microwave data from the Canadian RADARSAT-2 satellite.

The combination of optical and microwave data has been shown to produce more accurate maps than maps created from either single source. These maps are created and validated using data collected by people in the field. For the Prairies, “we have agreements with the provincial crop insurance companies,” Campbell says. “It’s not a perfect system but we’re about 85 per cent and 90 per cent accurate and working to improve that.”

Satellites don’t stay in orbit forever and Campbell says a backup is always an asset. Canada has plans to launch a constellation of three microwave satellites in 2018, the RADARSAT Constellation Mission (RCM), to gather data that’s even more detailed and precise than what’s available now.

“There are more uses than I ever thought of,” Campbell says. For instance, crop placements, crop monitoring, research, commodity marketing, land use management and even flood forecasting in Manitoba.

Microwave data collected by the European SMOS (Soil Moisture and Ocean Salinity) satellite allows Campbell’s team to operationally measure soil moisture in the top five centimetres of soil. He says most people don’t realize the Earth naturally radiates very low-level microwave energy and a satellite in space can pick up the variations in waves. Water absorbs microwave energy. When the microwaves radiate out from the Earth and pass through the soil, some of them are captured by moisture in the soil. 

According to Campbell, in September 2015, Statistics Canada did not do a farmer survey, opting to use AAFC climate data to complete their crop yield forecast. Satellite data can describe how agriculture land is changing or evolving over the years, whether it’s farmland expanding by eliminating small woodlots or urban expansion covering agricultural land. These phenomena can be monitored year over year using the AAFC crop maps.

Campbell has compiled maps that helped document the areas where clubroot is developing in canola. Scott Keller, a farmer from Camrose County in Alberta, contacted AAFC, asking Campbell if he could map Camrose County to determine how often canola was grown in particular fields. Keller wanted to determine which fields grew canola most often, either in a tight rotation over multiple years or in succession, in order to determine if there was a correlation between the escalation of clubroot and the rotation schedule.
Canola crop
Map created by Campbell to monitor canola crop frequency in Camrose County, Alta. 
Photo courtesy of Leander Campbell, AAFC.

That’s just one way satellite data can support crop management. Campbell says he’s confident that as computer technology and Internet costs come down, AAFC will be able to create more products from data because they can monitor specific areas once or several times over a growing season, or over years.

Campbell and his six colleagues who create the crop maps, soil moisture reports and the normalized difference vegetation index (NDVI) reports have an international presence as well. “I know some of our maps are incorporated into more global crop assessments for global market information, especially the NDVI maps,” Campbell says.

He explains that several nations around the world use satellite imagery to monitor their own crops. They meet on a monthly basis and compare data on major crops like corn, wheat, rice and soybeans through an organization called GEOGLAM. The group’s website states its vision is to “use coordinated, comprehensive and sustained Earth observations to inform decisions and actions in agriculture through a system of agricultural monitoring.” https://cropmonitor.org

Canadian farmers can access existing maps and data products online from the AAFC website. Because these maps are highly detailed, producers may experience difficulty downloading them on devices while in the field, but they can still view them online. According to Campbell, that’s the sort feedback he needs to hear from farmers.

“In our little world we have all these high-end computers and that works fine for us, but it may not be the most practical thing for others,” Campbell says. And, he’s looking forward to finding more ways to help farmers and make the website more user-friendly.

As satellite mapping matures, both farmers and scientists will view agriculture in new ways and Campbell is enthusiastic about the possibilities. “It’s a really exciting time to be in our field,” Campbell says.


This article originally appeared in the June 2016 issue of Top Crop Manager West

Published in Emerging Trends
Page 1 of 17

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