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Focus On: Pulses
4 Managing lygus in faba bean by Donna Fleury
8 Weeding out in lentil by Bruce Barker
10 Fungicide insensitivity in pulses by Carolyn King
DEREK CLOUTHIER EDITOR
PROTECTING OUR FAVOURITE PULSE CROPS
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here is no denying the health benefits of pulse crops like lentils, soybeans, and chickpeas, but for some, particularly children, seeing a pulse crop on their plate or in their bowl is not always a welcome sight. I am no exception. Though I love pretty much every bean out there today – one of my favorite summer salads is mixed beans with celery, red onion, and apple cider vinegar – there was a time when I picked kidney beans out of my chili and wouldn’t go near a bean salad with a 10-foot pole.
This childhood aversion to beans and peas should never have been the case with the numerous ways pulses, like lentils, chickpeas, and dry beans, can be used in various dishes from around the world. My family may not have been the most adventurous of eaters, but, as I’ve broadened my culinary horizons, I have come full circle when it comes to pulse crops, frequently enjoying dishes such as hummus, curried lentils, and Mexican black bean salad. Many pulses coming from Canada are still used as livestock feed, so pigs and cows certainly appreciate the value of a good lentil.
Given their versatility and health benefits, it’s important for growers, agronomists, and agriculture companies to use and produce the very best products to help protect pulse crops from diseases, weeds and insect damage.
Diseases like Fusarium root rot, seedborne bacterial diseases such as aster yellow and blight, and fungal diseases like sclerotinia white mold and anthracnose can all have a devastating impact on the health and yield of pulse crops. Weed control is also essential for the survival of pulse crops, as pulses do not compete well with weeds.
Implementing an effective disease and weed management plan is important for farmers, and part of that plan includes the use of fungicides and herbicides.
In addition to using the right herbicides and fungicides, growers should employ an effective crop rotation plan, use quality seeds, and plant early. Monitoring your crop for signs of disease and weeds is also crucial to try and nip it in the bud early, particularly because there are fewer options for weed control in pulses than there are in other crops like wheat and canola. A pre-emergence herbicide plan to target areas of your field where weeds typically pop up is a good place to start. Avoid relying on one single herbicide to avoid resistance, and don’t have tunnel vision and only address what you see in your field – consider the possibility that other weed types could emerge at some point during the growing season.
Pulse crops have become an essential crop in the Canadian Prairies, experiencing a significant increase in seeded area back in 2001 and have never looked back. The Prairie climate is ideal for pulse crops, and, given their importance for Canadian exports and overall value from a health perspective, pulse crops should be a point of pride for all Canadians.
ON THE COVER:
Damage from lygus bugs visible in the seeds inside the pods after the no-choice chamber experiments. Photo courtesy of Teresa Aguiar Cordero, University of Saskatchewan. @TopCropMag /topcropmanager @TopCropManager
MANAGING LYGUS IN FABA BEAN
New tools under development for mitigating damage and reducing economic impacts.
by Donna Fleury
For faba bean growers, lygus bug is a problem pest that can quickly cause economic damage and downgrading even at small numbers. Researchers are trying to address knowledge gaps specific to lygus in faba bean crops and investigate potential strategies and tools for mitigating damage and reducing economic impacts.
“In our Lab, we specialize in insect ecology and integrated management for a range of pests and beneficial insects, including lygus,” says Sean Prager, associate professor and principal investigator of the Prager Lab at the University of Saskatchewan. “Lygus is a pest of various crops but is particularly a concern for faba bean because it is a later-season crop and often the only green crop around after canola and other crops have been harvested. Lygus tend to move into faba bean during the podding stages, feeding directly on the pods. The market for human consumption has very low tolerance for seed damage, with faba bean samples that have greater than one per cent perforated damage downgraded to Number 2 Canada. This can reduce the price of faba bean by as much as $3/bushel, resulting in significant economic losses.”
Annual field surveys were first initiated in 2017 to help identify the incidence and severity of lygus infestations and seasonal variability. Crops were sampled at the early podding stage across the faba bean growing areas across Saskatchewan by lab researchers in collaboration with the Ministry of Agriculture, Crop Insurance and the Saskatchewan Pulse Growers. The samples were sent to Prager’s Lab for identification and analysis. The field surveys continue, and new research projects are building on this information and knowledge.
In Prager’s Lab, graduate student Teresa Aguiar Cordero is conducting different experiments to learn more about the damage and economic impact of lygus bug feeding on faba bean. In the first experiments, under controlled chamber conditions, a series of no-choice bioassays were conducted to quantify the relationship between lygus bug numbers and the resulting damage to faba bean pods. Different species of lygus were put in controlled chambers at different levels, starting with one and gradually increasing numbers, for different amounts of time.
“The objective of this experiment was to provide an estimate of how many lygus feeding on faba bean pods and for how long before economic damage and downgrading occurs,” explains Prager. “This information is expected to indicate how severe the damage is at different levels and when to take action, as well as potentially provide
Damage from lygus bugs visible in the seeds inside the pods after the no-choice chamber experiments.
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a method of determining economic thresholds. Although the results are very preliminary, it appears that economic damage happens very quickly, and even at one or two lygus for as little as one day of feeding may be enough to cause downgrading.”
In the next experiment, the objectives were to understand the feeding behavior of lygus bugs in faba bean and determine how long it takes to cause seed damage. When lygus bug adults and nymphs feed on pods, they also inject digestive enzymes into the pods and developing seeds. These enzymes cause visible damage, leaving behind dark-coloured perforations in the seed.
“In this experiment, we used an electrical penetration graph (EPG) technique to gain a better understanding of the feeding behavior of lygus bugs in faba beans,” says Prager. “It is a complicated method but can provide information on precise feeding patterns of lygus bugs. Our preliminary results suggest this is happening much faster than we thought and likely too quickly to be able to take action. It appears that if you see one lygus, damage may have already occurred. This really changes the strategy for developing economic thresholds and becomes a slightly different problem to solve. We didn’t anticipate the damage to be this severe this quickly. Therefore, we are trying to develop other tools and management options.”
Controlling lygus with insecticides in faba bean is difficult because usually there are both flowers and pods on the plants when the lygus are in the field. Faba bean relies on pollinators, so growers must be careful when selecting an insecticide. Another consideration is pre-harvest intervals for insecticides, which may be challenging with the later infestations of this longer season crop. Therefore, trying to control lygus in adjacent crops may be another option.
“We are collaborating with research scientist Hector Carcamo at the Agriculture and Agri-Food Research Station in Lethbridge to try to determine where the lygus are coming from,” explains Prager. “We suspect lygus comes from canola or other crops, and after they are
harvested the lygus move to faba bean as the next green food source. We want to know if we could predict the level of lygus infestation expected in faba bean based on what is in neighbouring crops. And would it be possible to control lygus in neighbouring crops and reduce populations enough, so they don’t move into the faba bean crop.”
Researchers are investigating the potential of trap crops as another possibility to reduce populations of lygus before they can move into faba beans. To do that, additional experiments are being conducted to determine the preferences of lygus when given a choice of different crop and plant species. The objective is to identify potential trap crops that could attract lygus populations as part of a management program to reduce the impact of lygus bugs on faba bean crops.
“The research is tricky because it requires doing experiments with multiple plants in a controlled environment that all need to be at the appropriate stage relevant to faba bean for testing,” says Prager. “Some crops such as faba bean don’t grow that well in the greenhouse, so it is challenging to get the crops to be at the right stages at the same time. We are testing various crops such as alfalfa and others and trying to find which crops lygus prefer. We know lygus does like alfalfa, but we don’t yet know whether they like it enough to be the best trap crop. These experiments are just getting underway, so we don’t have any results yet.”
“We are continuing our research to find better-integrated management options for lygus in faba bean crops,” adds Prager. “For faba bean growers who know they have a lot of lygus in neighbouring canola or alfalfa, trying to keep the crops as far apart as possible is recommended. Also considering a trap crop where lygus can more easily be controlled with insecticides may be an option. We are making progress towards better information and understanding potential management tools to minimize damage and decrease economic losses for growers.”
Trials using the electrical penetration graph (EPG) technique provides information on precise feeding patterns of lygus bugs.
A series of no-choice experiments where a specific number of lygus were placed in a growth chamber and allowed to feed for a predetermined amount of time to quantify damage to faba bean pods.
WEEDING OUT IN LENTIL
Multiple research trials look at expanding weed control options.
by Bruce Barker
Challenging times in weed control call for new approaches in lentil. As a poor competitor and with the rise of herbicideresistant weeds, researchers at the University of Saskatchewan investigated new herbicide options and approaches to help improve weed control in lentil.
“Reducing the reliance on herbicides is important to the long-term sustainability of the agricultural sector, including pulse crops. It would also reduce the cost of weed control and lessen its impact on the environment. However, good weed management in the short-term will nevertheless require well-timed, efficacious herbicide applications,” says Chris Willenborg, professor at the University of Saskatchewan’s Plant Sciences Department. “Managing weeds using a number of tactics must be incorporated into research programs to ensure the longterm viability of the pulse crops sector.”
Willenborg conducted five weed control projects from 2016 to 2021 that were funded by the Saskatchewan Pulse Growers. The goal was to try to expand the number of active ingredients that might be registered in lentil, and to see if existing herbicides could be applied at different times or with different application methods to enhance weed control.
Searching for new herbicide options
In the first of three trials investigating alternative modes of action,
Willenborg looked at lentil crop safety to a Group 5 active ingredient, amicarbazone, with a trade name Xonerate. A 2016 greenhouse study found there was potential to use amicarbazone for wild mustard and kochia control with adequate crop safety. Subsequently, field trials were conducted at Agriculture and Agri-Food Canada Scott, Sask., and the U of S research farm at Kernen in 2017 and 2018. The soil at Scott is a loam soil and the Kernen farm has heavy clay.
Five increasing rates of amicarbazone were applied pre- or postemergent. Post-emergent weed control was variable in 2017, so a surfactant was utilized in 2018. CDC Maxim lentil was the variety seeded.
The short story is that over the two years, weed control and crop safety were variable and unacceptable.
“The visual injury and NDVI reduction from amicarbazone application at Kernen, and the reduction in lentil yield at Scott, both indicate that the selectivity of amicarbazone is not sufficient to warrant further research for post-emergent application in lentil,” says Willenborg.
A second study investigating a new mode of action for lentil was conducted in 2018 at Kernen. Pyridate is a Group 6 herbicide sold under the trade name Tough 600EC. It targets broadleaf weeds such as redroot pigweed, lamb’s quarters, kochia and wild mustard, and can be applied pre- or post-emergent on corn and chickpea.
ABOVE: Five research projects at the U of S sought to increase weed control options in lentil.
PHOTO BY BRUCE BARKER.
Treatments for layering fall and spring pre-herbicides for managing Group 2 resistant kochia and wild mustard in lentil.
Crop tolerance and weed control trials were conducted at Kernen in 2018. Rates applied to CDC Maxim lentil were 0.5x, 1x and 2x of registered rates, applied pre- or post-emergent. None of the application rates applied pre-emergent caused unacceptable visual injury to lentil. There was a trend of increasing yield with higher pre-emergent application, but yields were not significantly different than the untreated check.
“The study in 2018 revealed the potential for the use of pyridate as a pre-seed burnoff treatment in lentil,” says Willenborg.
All of the post-emergent pyridate application rates caused unacceptable visual injury to lentil. Yields also trended downward with increasing rates of pyridate. Willenborg says post-emergent application in CDC Maxim lentil resulted in unacceptable injury and reduced yields at rates that would be required to control broadleaf weeds.
A third trial was conducted looking at lentil tolerance to Group 14 herbicides pyraflufen-ethyl and fluthiacet-methyl when applied post-emergently. Pyraflufenethyl is an active ingredient found in several herbicides, including Goldwing, a tank-mix with MCPA, which is registered on lentil when applied pre-emergently. Fluthiacetmethyl is registered as Cadet herbicide in the United States for post-emergent application to soybeans.
The active ingredients were applied when CDC Maxim lentil reached the two to three leaf stage. Two different formulations of fluthiacet-methyl were applied, while the pyraflufen-ethyl was an EC formulation. Three increasing rates were applied to as-
sess crop tolerance and weed control.
All of the pyraflufen-ethyl rates applied caused unacceptable injury over 10 per cent and severe chlorosis over 30 per cent.
Treatments with fluthiacet-methyl at all rates had acceptable crop injury less than 10 per cent at 28 days after application. There was some unacceptable damage at 14 days after application, but it had subsided by 28 days after application.
Willenborg says commercially acceptable control greater than 80 per cent of stinkweed and redroot pigweed occurred when higher rates of fluthiacet-methyl was used. Higher rates of EC formulation of Cadet provided good control of common lamb’s quarters, but the other SC formulation only suppressed it.
No herbicide treatment effectively controlled wild buckwheat or wild mustard.
“Overall, this study confirms that lentil cannot tolerate pyraflufen, but fluthiacetmethyl can effectively control several weed species at normal and high rates without negatively impacting crop yield,” says Willenborg. He emphasizes, though, that fluthiacet-methyl was included for experimental purposes only, is not registered and likely won’t be in lentil.
Layering herbicides improved weed control
A study was conducted in 2017, 2018 and 2021 at Kernen to evaluate fall pre- and spring pre-emergent combinations for managing ALS-resistant Group 2 kochia and wild mustard in lentil. Eighteen different herbicide layering treatments were ap -
plied. Herbicide applications in fall included Focus (carfentrazone + pyroxasulfone), Fierce (pyroxasulfone + flumioxazin), Valtera (flumioxazin), PL1958 and a fall pyroxasulfone + Heat spring pre-emerge.
A post-emergent herbicide treatment of metribuzin + fluthiacet at one-half and full rates followed the pre-emergent applications. For comparison, control treatments with no pre- or post-emergent treatments were also included.
SOURCE: WILLENBORG ET AL.
PL1958 is a liquid flumioxazin premix herbicide registered and sold in the U.S. as Panther Pro and is not registered in Canada. Willenborg emphasizes it was included for experimental comparisons and should not be used in Canada.
Crop injury was assessed in 2017 and 2018, and at 14 days after treatment, all the treatments, pre- and post-emergent, had phytotoxicity lower than the maximum tolerable level of 10 per cent. This indicated that a layering approach to weed control did not harm the crop.
Wild mustard control in 2017 at 14 days after treatment was almost 100 per cent when a half or full rate of metribuzin + fluthiacet was applied following any of the pre-emerge layering treatments. Control was substantially lower at less than 60 per cent when no pre-emerge treatment was applied. Results in 2018 and 2021 were variable due to drought conditions.
Overall, application of a pre-emergence herbicide alone was often as effective as applying both pre- and post-emergence herbicides in controlling weeds. The addition of a post-emergent herbicide on top of preemerge herbicides did not result in a significant increase in kochia control.
Crop yield was significantly greater when a full rate of metribuzin + fluthiacet was applied post-emergently than if a postemergent application was not made.
“While the trial showed pre-emergence herbicides were more effective than pre+ post-emergence applications, layering is still important to mitigate resistance by exposing weeds to two modes of action,” says Willenborg. “In addition, weeds may emerge after the residual impact of a preemerge is gone, and in these cases the incrop herbicide will become important.”
Always follow the label for application timing.
FUNGICIDE INSENSITIVITY IN PULSES
Understanding and managing this serious issue for Prairie pulse crops.
By Carolyn King
Fungicides are valuable tools for crop production, but the development of fungicide insensitivity (resistance) in a crop pathogen can blunt or even destroy a fungicide’s effectiveness. Over the past two decades, fungicide insensitivity has been documented in three important pulse diseases on the Prairies. The latest problem was first reported in 2019. However, this insensitivity issue need not continue to increase. Pulse growers now have good options for managing these insensitive pathogen populations and for extending the longevity of fungicide actives.
About the problem
“Fungicide insensitivity is a problem in the major foliar diseases in our pulse crops: ascochyta blight in chickpea, anthracnose of lentil and mycosphaerella blight in pea,” notes Michelle Hubbard, a pulse pathologist with Agriculture and Agri-Food Canada (AAFC).
The pathogens involved are: Ascochyta rabiei causing chickpea ascochyta blight, Colletotrichum lentis causing lentil anthracnose and Mycosphaerella pinodes causing mycosphaerella blight in field pea.
TOP: The second Group 11 insensitivity problem discovered in Saskatchewan was in mycosphaerella blight of field pea.
MIDDLE: Insensitivity to strobilurin fungicides in lentil anthracnose was first confirmed in Saskatchewan lentil fields in 2019.
For all three pathogens, widespread insensitivity to all strobilurin actives, the Group 11 fungicides, has been confirmed on the Prairies.
The risk of fungicide insensitivity is influenced by the fungicide, the pathogen and agronomic factors, as well as weather conditions that favor disease development.
“One of the biggest factors affecting insensitivity risk is fungicide selection pressure. Historically, the Group 11 actives have been the mainstay for disease control in our pulse crops. That pattern of using Group 11s over and over has been occurring not only in pulses but also in canola, wheat, and other common crops on Prairie farms, and has led to increased selection pressure on the pathogens,” says Meagen Reed, an agronomy manager with the Saskatchewan Pulse Growers (SPG).
“Fungicide insensitivity is a problem in the major foliar diseases in our pulse crops: ascochyta blight in chickpea, anthracnose of lentil and mycosphaerella blight in pea.”
approaches to disease management in pulses and effective fungicides. As long as we are managing in a smart way, we needn’t have problems with fungicide insensitivity in our pulse crops.”
Chickpea ascochyta insensitivity
“Fungicide groups that dominate use in our pulse crops are Groups 11, 7 and 3. Most products are a combination of two or three of those. But the strobilurins are still commonly the base in these combinations.”
In addition to the high use pattern for the strobilurins, they are also at high risk for insensitivity because they act on a single target site in the pathogen. With a single gene mutation, called G143A, a pathogen gains a high level of insensitivity to all Group 11 actives.
Each of the three pathogens with documented Group 11 insensitivity has some characteristics that make them prone to developing fungicide insensitivity.
For instance, all three are polycyclic, meaning that they have multiple life cycles in one growing season. That increases the likelihood that several fungicide applications may be needed in a single season to control the disease.
AAFC plant pathologist Bruce Gossen also notes that Ascochyta rabiei and Mycosphaerella pinodes produce wind-blown spores that can spread the pathogen, including any insensitive biotypes, for long distances.
As well, Ascochyta rabiei and Mycosphaerella pinodes each have a sexual reproduction phase. Sexual reproduction generates greater genetic diversity than asexual reproduction. This increased diversity increases the likelihood that some of the individuals in the pathogen’s population may have a mutation that makes them insensitive to a fungicide. Repeated use of that fungicide will select for the insensitive individuals because they can survive the fungicide applications and reproduce, becoming a larger part of the pathogen’s population with each generation.
“So, we have this perfect storm of high use patterns for a fungicide at high risk of insensitivity and polycyclic pathogens capable of adapting quickly,” says Reed. “And some growers in some parts of the province have tighter rotations, growing their pulse crop every one-in-two or one-in-three years. And we are seeing two or three applications of fungicides in lentils in some areas, and up to four to six applications in chickpea. That is a lot of selection pressure.”
Although fungicide insensitivity in Prairie pulses is a serious concern, Gossen puts it in perspective: “We have a chance to learn from other places in Canada and the world where fungicide insensitivity is a much bigger issue. And these days, we have effective
The first fungicide insensitivity issue reported in Prairie pulse crops was for ascochyta blight in chickpea, the most serious chickpea disease in Saskatchewan. The problem developed remarkably quickly.
In 2003, Group 11s were introduced in western Canada. In 2004, Gossen’s research team detected Group 11 insensitivity in a few Ascochyta rabiei isolates from Saskatchewan. Then a 2006 survey confirmed this insensitivity in several chickpea fields in the province. By 2007 to 2008, his team found that almost all isolates were insensitive to the Group 11s.
“Ascochyta blight in chickpea sometimes needs three or four fungicide applications, and back then we had only one really effective fungicide for that. So, we saw a very rapid increase in fungicide insensitivity in Saskatchewan,” Gossen explains.
More recently, Hubbard led a survey of Ascochyta rabiei insensitivity in Saskatchewan commercial chickpea fields in 2019, and then did some insensitivity testing as part of her 2022 trial looking at fungicide use in different chickpea varieties.
When Hubbard and her research team found ascochyta blight on chickpea plants in these two studies, they used a PCR-based test to check for the G143A mutation in the isolates to see which ones were insensitive to all Group 11 actives.
“We found that insensitivity to Group 11s is very common in Ascochyta rabiei in chickpea,” says Hubbard. For example, in the
The first fungicide insensitivity issue reported in Prairie pulse crops was for ascochyta blight in chickpea.
PHOTO COURTESY OF MICHELLE HUBBARD, AAFC.
seem to work. My trials date back to 2018. Lana Shaw [research manager for the South East Research Farm] and Bill May [crop management agronomist with AAFC at Indian Head] had done work in previous years,” she says. The most recent project was funded by Saskatchewan’s Agriculture Development Fund (ADF), Western Grains Research Foundation and SaskFlax and led by May.
“The main take-home message from our research on intercropping chickpea with flax is that, if there is disease, then most of the time there is less disease with intercropping, but not no disease.” That finding holds true whether you plant the chickpea in the same row as flax or in a separate row.
In addition, Hubbard is leading a three-year project, which started in 2023, to assess the effects of different fungicide regimes in combination with intercropping chickpea and flax. She wants to see if the use of intercropping can reduce the need for fungicide applications or increase the effectiveness of those applications. As well, she has a trial comparing different flax and chickpea varieties to find out if some varieties are better suited to intercropping than others. This project is funded by ADF and SPG and led by Randy Kutcher at the University of Saskatchewan.
Pea mycosphaerella blight insensitivity
A few years after the chickpea ascochyta insensitivity problem was discovered in Saskatchewan, a second fungicide insensitivity issue was found. This time, it was in mycosphaerella blight of field pea, a damaging disease that is common in Prairie pea-growing areas. The disease is actually a complex of several pathogens, but the main fungus in the complex on the Prairies is Mycosphaerella pinodes.
The Group 11 insensitivity in Mycosphaerella pinodes was identified by Gossen and his colleagues. He says, “After seeing the rapid increase in insensitivity in chickpea ascochyta blight, my program got interested in mycosphaerella blight in field pea because Ascochyta rabiei and Mycosphaerella pinodes share many of the same characteristics that increase the risk of fungicide insensitivity. And there was a lot of fungicide use [in the early 2010s] because of grower interest in applying strobilurin fungicides not only to control the disease but also to improve crop health and growth.”
First, the researchers tested the sensitivity of isolates that had been collected in Alberta, Saskatchewan, North Dakota, and Washington State before 2003. All of the isolates were sensitive. Then, they tested samples collected in 2010 and 2011 in the same regions. A small percentage of the isolates from Alberta and Saskatchewan were insensitive; none of the U.S. isolates were insensitive.
Then, when the researchers tested Saskatchewan isolates collected from 2013 to 2016, they found that 72 per cent were insensitive to Group 11s. Gossen adds, “When we looked at the issue again a few years later, the insensitivity had increased up to about 95 per cent.”
2019 survey, Ascochyta rabiei was detected in 33 samples collected from 29 fields (out of a total of 44 fields surveyed). Group 11 insensitive isolates were present in all 33 samples. Only eight also had some Group 11 susceptible isolates.
Hubbard is also investigating intercropping of chickpea with flax as a way to reduce fungicide use when managing chickpea ascochyta. “I’m very excited about intercropping because it does
Lentil anthracnose insensitivity
Group 11 insensitivity in lentil anthracnose, one of the most important lentil diseases on the Prairies, was first confirmed in Saskatchewan lentil fields in 2019.
Hubbard is currently leading a lentil anthracnose insensitivity project funded by SPG and ADF. Surveys in 2020, 2021 and 2022
Using integrated disease management strategies, like intercropping chickpea and flax, to manage foliar diseases can help reduce the risk of developing fungicide insensitivity.
Researchers are also testing for insensitivity to Group 3 and 7 fungicides in samples of lentil anthracnose.
PHOTOS COURTESY OF MICHELLE HUBBARD, AAFC.
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collected samples of the disease across much of Saskatchewan’s lentil-growing area. Hubbard’s team tested the Colletotrichum lentis isolates from the samples for the G143A mutation.
“We found that insensitivity to Group 11s is common in Saskatchewan’s lentil production region,” says Hubbard. The majority fields had a mix of sensitive and insensitive isolates, a small percentage of fields had only insensitive isolates and an even smaller percentage had only sensitive isolates.
“Be aware of the fungicide groups and actives you are using, and how often you are using them across the farm, not just in your pulse crops.”
The project also includes testing of Colletotrichum lentis isolates for insensitivity to Group 7s and Group 3s. Group 7s have a medium to high risk for fungicide insensitivity, and Group 3s have a medium risk.
Hubbard has been collaborating on this project with Gossen. His research team has been helping with some of the project tasks, including testing the Group 7 actives.
“What we have found is encouraging; there is no evidence that there is insensitivity to Group 7s,” she says. They plan to start testing for insensitivity to Group 3s in the next few months.
Reed notes that SPG also funded a 2021 greenhouse study by Insight Plant Health to test the effectiveness of different fungicides for controlling Group 11 insensitive lentil anthracnose. One of the key findings was that Saskatchewan growers should not rely solely on Group 11 actives to control this disease. Details of the findings are available on the SPG website.
Tips for tackling insensitivity
Hubbard, Gossen and Reed all emphasize that having a good break between pulse crops in your crop rotation and having a diverse fungicide rotation are key practices in the battle against fungicide insensitivity.
“Be aware of the fungicide groups and actives you are using, and how often you are using them across the farm, not just in your pulse crops,” says Reed. She recommends using many different modes of action in your fungicide rotation, including tank mixes and products with more than one active, particularly if multiple fungicide applications are needed in a single growing season.
She says, “Also, do not apply Group 11 actives alone, and try to avoid using Group 11 products more than once per season. If you’re using a product with a Group 11, make sure the other active has an effect on your target pathogen.”
“The good news is that a number of new actives and new fungicide groups have been registered on pulses in the last few years. Growers have not only effective fungicides but options for rotating effective fungicides,” says Gossen.
He adds, “The pulse industry has been very successful in attracting research interest from chemical companies to explore what actives are effective and to move those forward. Another really positive thing is the emphasis that the industry is placing on making fungicide products with more than one active, which guards against the rapid development of fungicide insensitivity.”
Reed is excited to see these new product options. She also stresses the importance of applying fungicides according to their label, such as using proper timing, recommended rates and correct water volumes. “Especially with a disease like lentil anthracnose, which typically starts on the lower part of the plant, penetrating the canopy with your spray is really important, and water volumes are critical for that.”
Hubbard offers some tips specifically for chickpea ascochyta and lentil anthracnose. “Assume that any ascochyta on your chickpeas is insensitive to Group 11s. Don’t rely on fungicides that only have a Group 11 active ingredient. Especially consider, later in the season, using a contact-based fungicide that doesn’t have a Group 11 at all. Contact-based modes of action are at even a lower risk of insensitivity than the Group 7s and Group 3s,” she says.
“Similarly for lentil anthracnose, assume that it is insensitive to Group 11s, and don’t rely on fungicides that only have a Group 11. And consider contact-based fungicides, or fungicides that have, say, Group 3 actives without a Group 11.”
Hubbard also recommends, “Use clean seed. And consider choosing some of the new chickpea varieties and pay attention to the ascochyta disease ratings of the varieties.” (At present, commercially available lentil varieties are susceptible to the main race of Colletotrichum lentis on the Prairies.)
As another way to reduce your fungicide use, Hubbard suggests trying intercropping chickpea and flax, perhaps starting with a small area if you’re new to intercropping. In the future, she hopes to assess lentil intercropping as a foliar disease management tool.
And last but not least, Reed, Gossen and Hubbard all underline the importance of scouting for disease and carefully assessing whether a fungicide application is needed. And while you’re scouting, watch for signs of fungicide insensitivity.
Following these best management practices will help keep fungicide insensitivity issues at bay.
Faba beans are grown throughout the Canadian Prairies.
PHOTO COURTESY OF ISTOCK / GETTY IMAGES PLUS
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