Early blight, caused by the Alternaria solani fungus, is found in most potato growing regions. Foliar symptoms include small, brown, irregular or circular-shaped lesions that form on the potato plant’s lower leaves later in the season. The disease prefers warm, dry conditions to develop, and can be more severe in plants that are stressed and weakened.
Brown spot, caused by the Alternaria alternata fungus, is closely related to early blight and is found wherever potatoes are grown. Unlike early blight, brown spot can occur at any point during the growing season, producing small, dark brown lesions on the leaf surface.
Aprovia Top fungicide combines two modes of action with preventative and early curative activity on these two key diseases. Difenoconazole (Group 3) is absorbed rapidly by the leaf and moves from one side of the leaf to the other to protect both surfaces against disease. Solatenol (Group 7 SDHI) binds tightly to the leaf’s waxy layer and is gradually absorbed into the leaf tissue to provide long-lasting, residual protection.
Aprovia Top is available now for use in 2017 production. In potatoes, one case will treat up to 40 acres.
The product contains propiconazole (Group 3), a curative fungicide that acts on already-present disease to halt further infection, azoxystrobin (Group 11), a preventative fungicide that provides disease protection by moving into new growth, and Solatenol, a powerful Group 7 succinate deyhydrogenase inhibitor (SDHI) fungicide. The unique chemistry in Solatenol allows it to bind to the waxy layer of the entire leaf, where it is absorbed slowly over time to provide long-lasting residual protection.
Syngenta research trials show Trivapro to be highly effective on key cereal diseases, including barley scald, tan spot and net and spot blotch, while providing improvement in yield potential.
Trivapro also demonstrates superior performance on major rusts, including leaf rust (Puccinia hordei), stem rust (P. graminis) and stripe rust (P. striiformis).
The Trivapro co-pack should be applied once at early flag leaf timing. Growers should consult the Trivapro product label for additional information.
In addition to being registered on barley, wheat and oats, Trivapro is also registered for use in corn and soybeans to protect against several foliar diseases, including Northern corn leaf blight and grey leaf spot in corn, and Septoria brown spot and frogeye leaf spot in soybeans.
Trivapro fungicide will be available in spring 2017 as a 40-acre co-pack or 400-acre bulk co-pack.
Visit syngenta.ca to learn more.
In Saskatchewan, provincial guidelines recommend spraying fungicides on durum wheat at the flag leaf stage for leaf spots and the flowering stage for Fusarium head blight (FHB), if warranted. But others are also recommending fungicide applications at earlier growth stages on a preventative basis. Yet little evidence existed, until recently, on whether this was a viable practice.
However tempting it is to throw some fungicide in with a herbicide application to save on application costs, Myriam Fernandez cautions it doesn’t help prevent disease and can even negatively impact quality.
“Our results suggest that under variable environmental conditions in Saskatchewan, not always conducive to the development of high disease levels in wheat, early preventative fungicide application on durum wheat should not be recommended as a strategy to improve productivity, even when followed by a second application,” Fernandez says.
Fernandez is a research scientist with Agriculture and Agri-Food Canada (AAFC) at the Swift Current Research and Development Centre. Between 2004 and 2006, she led a study investigating single and double applications of foliar triazole fungicides at various growth stages, and the impact on FHB, deoxynivalenol (DON) concentration, dark kernel discoloration and grain traits in durum wheat. A second study was led by research scientist Bill May at AAFC’s Indian Head Research Farm between 2001 to 2003, which looked at the impact of single and double fungicide applications at flag leaf emergence and flowering stage on disease control and yield and quality of durum. Both studies were recently published in the Canadian Journal of Plant Science.
In Fernandez’s research, plots were established at the South East Research Farm in southeast Saskatchewan, and the trial ran for three years. The previous crop was canola in each year. AC Avonlea durum was seeded using a no-till plot drill. Standard agronomic practices were used.
Folicur was applied at the recommended rate in all years. Six fungicide treatments were conducted:
- at stem elongation (GS 31);
- when flag leaf was half emerged (GS 41);
- at early to mid-anthesis (flowering) (GS 62-65);
- at stem elongation and mid-anthesis;
- at flag leaf emergence and anthesis.
Leaf spotting disease, FHB incidence, Fusarium kernel infection, DON concentration, grain yield and quality parameters were measured. Percentage leaf spotting severity on the flag leaves was evaluated in 2004 and 2005, but not in 2006 because of poor disease development.
Fernandez says that in most cases, a fungicide application at stem elongation was not effective in reducing Fusarium diseases, nor in improving yield and grain characteristics. She explains that none of the early, single applications were consistently different from the unsprayed control. Fungicide application at flag leaf emergence was more effective in reducing disease levels later in the growing season or improving grain characteristics than an early application at stem elongation. An application at the flowering stage resulted in the most consistent reduction in Fusarium levels, leaf spotting and improvement in kernel size.
This is consistent with fungicide application timing for FHB control. Saskatchewan Agriculture recommends fungicide application when at least 75 per cent of the wheat heads on the main stem are fully emerged to when 50 per cent of the heads on the main stem are in flower.
The double fungicide applications at either stem elongation/flag leaf emergence and anthesis were no more effective than a single fungicide application at flowering, and would have resulted in increased fungicide and application costs.
None of the fungicide treatments resulted in a significant grain yield increase. “We can conclude that fungicide application, single or double, might be profitable only in the presence of higher disease pressure levels, with more suitable growing conditions for disease development and plant growth,” Fernandez says.
Grain downgrading might result from early and frequent fungicide application
The early fungicide applications also had a negative impact on dark kernel discoloration, a key quality parameter for durum wheat with tolerances for total smudge and black point at five per cent in No. 1 Canadian Western Amber Durum (CWAD) and 10 per cent for No. 2 CWAD. The discoloration would have resulted in downgrading for the early application treatments.
Fernandez says the results also indicated potential for a consequent increase in kernel discoloration like black point and red smudge after early fungicide treatment, which was associated with greater kernel size. This effect has also been reported with other fungicides from other wheat growing regions of the world.
The 2001-2003 study conducted in southeast Saskatchewan and southwest Manitoba led by May at Indian Head looked at the impact of single and double fungicide applications at flag leaf emergence and flowering stage on Fusarium-damaged kernels and other kernel diseases, leaf spotting, and resultant grain yield and quality of durum wheat.
Disease levels averaged over all site years were high enough to result in an 8.5 per cent yield increase from the application of fungicides. However, application at either flag leaf elongation or flowering stage also increased black point by 49 per cent, from 0.38 per cent to 0.56 per cent, and red smudge by 17 per cent, from 0.54 per cent to 0.63 per cent. In addition, double fungicide application further increased red smudge to 0.85 per cent, a 57 per cent increase compared to no fungicides being applied.
Effective August 2015, the Canadian Grain Commission changed the grading factors for CWAD. Red smudge is no longer a separate grading factor, but is still included under “smudge.” The maximum allowable level of smudge in CWAD is now 0.50 per cent for grade No. 1, and one per cent for grade No. 2 and grade No. 3. Prior to 2015, the tolerance level for red smudge in CWAD No. 1 was 0.30 per cent. In May’s research, the percentage smudge would have resulted in a downgrade to No. 2 CWAD.
May says two theories have been put forward to explain the association of red smudge and fungicides. The first is that an early fungicide treatment could result in an increase in kernel size that would facilitate the opening of the protective husk (glume), making it easier for fungi to penetrate and infect the grain. An alternative explanation is that the fungicide might alter the microbiological community on the spikes before or during kernel development, modifying the fungal interactions in that environment. More research is required under western Canadian conditions to determine the exact cause.
For foliar leaf disease control, Fernandez says the recommendation is still to apply a fungicide at the flag leaf stage, based on the level of disease infestation. This research found little benefit to applying fungicides for leaf spot diseases because the crop was not heavily infected. In other areas more conducive to disease, or years with high disease pressure, fungicide application at the flag leaf, or heading stage for leaf spotting disease could be profitable. The research also shows that current fungicide timing recommendations for FHB control at head emergence to 50 per cent flowering are still valid.
Fernandez cautions when applying any fungicide at any growth stage the potential development of fungicide resistance in wheat pathogens should always be considered, and unnecessary fungicide application may increase the risk of resistance developing.
May says faced with the recommendation of early fungicide application as a preventative measure regardless of disease pressure, farmers need to consider that early and frequent fungicide applications to durum wheat might reduce grain quality and result in downgrading and potential profit loss.
“I would expect that a fungicide application for control of FHB in durum wheat would provide a yield increase much more often than it would improve the grade of the harvested crop.” May says.
The Regalia product portfolio, with all formulations based on an extract of Giant Knotweed (Reynoutria sachalinensis), is a suite of preventative biofungicides for use on both conventional and organic crops. Regalia products prevent and fight diseases by triggering treated plants to produce disease-fighting biochemicals (induced systemic resistance), while simultaneously increasing leaf chlorophyll content to enhance plant health, crop yield and crop quality. Regalia Rx is not harmful to workers, food, beneficials and pollinators, according to a company press release, and can be sprayed right up to harvest to manage residues for export. Regalia Rx also has the minimum restricted-entry interval for workers to enter the field after spraying, increasing operational flexibility.
The Regalia Rx label is for suppression of Septoria leaf spot on wheat and aerial web blight (Rhizoctonia solani), Alternaria leaf spot, frog-eye leaf spot (Cercospora sojina) and white mould (Sclerotinia sclerotiorum) on soybeans.
Marrone Bio Innovations (MBI) has an agreement with Koch Agronomic Services to distribute Regalia Rx brands in the United States and Canada for large acre crops, such as wheat, soybeans, corn and alfalfa.
Ontario corn growers should be on the lookout for eyespot this season, warns Albert Tenuta. Photo courtesy of Krishan Jindal.
It might not be Ontario’s flashiest foliar disease on corn, or even the most economically devastating – both those awards go to Northern corn leaf blight – but eyespot was on the rise in 2015, and may be a cause for concern for Ontario growers in 2016.
According to Albert Tenuta, field crop pathologist for the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), eyespot is “one of those diseases that looks worse than it actually is – the impact on the corn is minimal.”
But it’s certainly not negligible. Common in the northern regions of the corn belt, eyespot becomes a problem in fields with residue from previous crops, or in continuous corn cropping. Caused by the fungus Aureobasidium zeae, infection generally occurs in the spring under cool, wet conditions; if it spreads to the upper leaves of the plant, it can cause reduced yields.
Tenuta is a member of Agriculture and Agri-Food Canada (AAFC) and OMAFRA’s annual corn disease survey team. Each year, on average, 200 corn plots across Ontario and occasionally Quebec are tested for major corn disease severity.
According to survey team member Krishan Jindal, a pathologist with AAFC’s Ottawa Research and Development Centre, the survey is a valuable tool for studying the distribution of Northern corn leaf blight and other foliar diseases, and identifying the pathogenic races moving through the province.
In 2015, eyespot showed a surprising surge in Ontario cornfields, along with Northern corn leaf blight. “Both diseases were found in almost all fields visited in southern and western Ontario, with 40 per cent of the affected fields having incidence levels of greater than or equal to 30 per cent and one-fourth of the fields having a severity of greater than or equal to five (greater than 20 per cent of the leaf area affected),” reads the report.
But Tenuta says eyespot doesn’t come as a shock to Ontario growers.
“We’ve always had eyespot. We’re just seeing more of it,” Tenuta says. “Many of these diseases are residue-borne, so as we leave more residue we’ll see more disease.”
What does this mean for growers? According to Tenuta, eyespot sometimes means a four to six bushels per acre yield loss, but in conjunction with other diseases, it can cause problematic stress on the plant.
“Where eyespot could be an issue would be on seed corn, where you have a relatively susceptible seed corn inbred,” he says. If the variety is susceptible to other foliar leaf diseases as well, these plants can’t tolerate as much stress, so the impact will be more substantial.
Variety, variety, variety
Management for eyespot comes down to variety.
“It doesn’t matter what disease we’re talking about – the first step is always effective resistant variety selection,” Tenuta says. “The most important decision a grower can make is which particular variety or hybrid they’ll select.”
If a field has a history of eyespot, growers should choose good-yielding varieties with decent resistance.
“The next thing is scouting to determine the amount of disease there: is it a threat? Is it down low in the canopy, or high up? If you’ve got eyespot, you have good conditions for other leaf diseases,” he says.
If disease reaches threshold levels, fungicide application is necessary.
When it comes to tillage, growers may have tough decisions to make when it comes to eyespot and other foliar leaf diseases, Tenuta says. Because eyespot relies on residues as a food source, removal of residues means the fungus can’t spread enough to trouble the next crop. “If they can’t feed, they can’t grow and they can’t infect,” he says.
But growers need to assess whether periodic tillage is right for their operations on a case-by-case basis. “It’s an effective tool, but you have to consider some of the other benefits of conservation tillage in terms of soil erosion. And just because we work the ground doesn’t mean the risk is eliminated – you might be reducing your in-field inoculum, but in many cases we have enough spores moving in from other fields,” he says.
As for the future? More eyespot resistant varieties may be on the way soon. Lana Reid, a research scientist at AAFC’s Ottawa Research and Development Centre, and her team are working on developing a number of inbreds with resistance to a variety of common foliar diseases, including CO450, a corn inbred line that is highly resistant to eyespot. It was made available to breeders in 2013.
“This survey, I would say, is of great value – it gives direction to the research and to breeding projects,” Jindal says.
June 20, 2016 - As the cereal crop's flag leaf stage approaches, many producers are wondering if a foliar fungicide application is worth their time and money.
"Most farmers want to know if they will get a yield and economic benefit from a foliar fungicide application," says Dr. Sheri Strydhorst, agronomy research scientist, Alberta Agriculture and Forestry, Barrhead. "Fungicide applications can be costly but, under the right conditions, can increase yields more than 30 per cent."
Strydhorst is leading a province wide-research project to help producers make fungicide management decisions. She says that, based on field research data from 2014 and 2015, they have come up with some helpful findings. "Our 10 site years of data show that a foliar fungicide application on AC Foremost wheat significantly increases yields when there has been at least five inches of rain from the time of seeding to end of June."
However, she cautions, it might not be that simple.
"For foliar diseases to infect crops and cause yield reductions, we need three things. First, we need a susceptible host. Second, we need the pathogen. Third, we need environmental conditions suitable for disease development.
"Our detailed foliar fungicide work was done with AC Foremost. It is an old cultivar that does not have the best genetic resistance to foliar diseases. Without the genetic resistance, this cultivar needs extra help to battle disease pressure."
However, not everyone is growing AC Foremost. In another study, Strydhorst found that Stettler wheat showed a yield increase with dual foliar fungicide applications in only one of nine site years; AC Foremost in seven of nine site years and AAC Penhold in four of nine site years. "Some cultivars are responding to fungicide applications while others are not."
This certainly complicates the decision making process, she says. "Producers should check disease resistance ratings on the cultivar they are growing. For example, AC Foremost is rated as susceptible to stripe rust and moderately susceptible to leaf spot while AAC Penhold is rated as moderately resistant to stripe rust and intermediate to leaf spot."
Dr. Kelly Turkington, research scientist at Agriculture and Agri-Food Canada, Lacombe, says that, "in a continuous wheat rotation, residue-borne diseases such as tan spot and septoria are likely present, so it is reasonable to expect a fungicide response with a susceptible cultivar the majority of the time, especially when the weather is favourable."
Strydhorst's research found yield increases with AC Foremost in response to fungicide applications when there was 1.9" of rain from seeding until the end of June. In this instance, winter wheat fields in the area were showing high levels of stripe rust. She says that with high levels of disease in the environment, fungicides can contribute to yield increases.
Turkington says each disease has specific conditions that favour development. "Stripe rust does not necessarily need a lot of moisture. Heavy dew can be enough to promote stripe rust. More rainfall facilitates inoculum production, dispersal (in the case of rain splashed pathogens) and host infection."
With the timely and frequent rainfall seen in much of the province, Strydhhorst suggests environmental conditions are right for tan spot and septoria pathogen growth.
"Our research shows that the more rain we have had, the bigger the yield benefit from the fungicide. For example, with 10" of rain from seeding until the end of June we observed a 26 bu/ac yield increase. But with 7" of rain the yield increase was reduced to 20 bu/ac. We still have one more year of research to conduct, but our initial findings suggest that more frequent and timely rains lead to bigger benefits from fungicide applications."
Turkington says stripe rust is a different pathogen and warm days with heavy dew resulting in several hours of leaf wetness per day can provide suitable environmental conditions for disease development in June. "However, rainfall and/or heavy dew in July can contribute to stripe rust development including on the head and peduncle also contributing to yield reductions."
While Strydhorst's research aims to simplify decision making, she says, as we all know, nothing is ever simple.
"At the end of the day, producers should assess: the disease rating of their cultivar, the presence of disease in their field and the environmental conditions. If you have poor genetic resistance, disease presence coupled with frequent, timely rains, it will likely be worthwhile to spray a foliar fungicide in 2016."
June 16, 2016 - Lentil growers realize that under most growing conditions, long-season lentil varieties seldom mature naturally. Lentils can mature unevenly, which can result in shatter losses as some pods become over-dry while others are still green. To help dry down the crop quickly and evenly, a grower has two options: they can desiccate with a harvest aid, or swath.
Harvest aids provide a number of benefits to lentil growers to help speed up harvest and dry down weeds. This makes early and efficient harvesting possible, and helps to make the harvest season more manageable.
Red lentil growers now have the option to use Heat LQ as a harvest aid, because BASF supports the use of the herbicide for pre-harvest applications on red lentils. Heat LQ is a Group 14 herbicide that is available in a convenient liquid formulation to help growers uniformly dry down crops. When tank-mixed with glyphosate, Heat LQ also manages tough weeds for the following season.
Calvin Watson, a grower from Avonlea, Saskatchewan, uses Heat LQ to dry down his lentils. "We've used glyphosate in the past to desiccate our lentils, but we've started using Heat LQ. It burns down the crop faster and brings it in so we can get out there and harvest faster. When we top it with glyphosate, Heat LQ also burns down the weeds better, so we can combine more easily," he said.
"Heat LQ when applied pre-harvest can help growers manage the workload during the busy harvest season by speeding up their harvest and controlling weeds to ensure a quality crop," said Danielle Eastman, Brand Manager, Western Herbicides and Clearfield at BASF Canada.
Maximum Residue Limits (MRLs) are established in most key markets. BASF is still in the process of establishing a MRL within the European Union. Until the MRL for that market is established, growers should check with grain handlers before using Heat LQ for pre-harvest applications on red lentils.
When using Heat LQ for pre-harvest applications, BASF recommends that growers follow the product label rates and timing recommendations in order to maximize their herbicide use. Heat LQ is supported for pre-harvest use on red lentil varieties only, and is not recommended on green lentils.
For more information on Heat LQ on red lentils, visit agsolutions.ca.
June 15, 2016 - Fusarium head blight (FHB) continues to prove a growing trend throughout Western Canada, plaguing cereal growers with the potential for serious losses in yield, quality and grade.
"Fusarium remains a cause for concern for cereal growers across Western Canada, causing reduced yields and grade quality," said Glen Forster, technical marketing specialist, fungicides, BASF Canada. "It can be a hard hit for many growers when it comes to their bottom lines."
Traditionally found in black soil zones, FHB can be spread through wind, rainsplash and infected grain and straw. It is also responsible for the development of mycotoxins, affecting the baking and milling quality of wheat, malting barley and livestock feed, and can affect human and animal health if it enters the food chain. Fusarium graminearum is only one of many species of the Fusarium disease, but considered one of the most important because of the impact that it has on yield and grain quality, and its ability to produce several toxins. In fact, a recent report by Alberta Agriculture and Food noted that Fusarium graminearum has cost Alberta producers between three and eight million dollars annually, due to reduced yields and downgrading caused by the disease.
According to a study recently released by the Canadian Grain Commission on the frequency and severity of Fusarium damaged kernels throughout Manitoba, Saskatchewan and Alberta, from 2003 to 2015, the damage and severity of the disease shows a consistent increase.
Signs and symptoms of Fusarium infection include shrivelled, lightweight, white or pink "tombstone" kernels. To take preventative action against the disease, Forster recommends using a fungicide to provide a line of defence against FHB and protect cereal yield and grade quality.
"Caramba fungicide is designed specifically to help manage Fusarium in cereals," said Forster. "The fungicide helps reduce the impact of the disease and can help growers preserve quality and protect the yield potential of their cereal crop. However, growers need to be vigilant when it comes to timing of application, as it is critical to ensure disease protection and best return on investment."
For fungicide application, Forster recommends when 75 to 100 per cent of stem heads are fully emerged in wheat, oats and rye crops and when 20 to 50 per cent are flowering. On barley, he recommends immediately after head emergence up to three days after full emergence to be effective.
Martin Prince farms in Delmas, Saskatchewan and has noticed an emergence of FHB in his farming area the last couple of years.
"In the past, Fusarium hasn't been a factor in our farming area, but we did notice it in 2014, and our neighbours did witness some. We have been using fungicides for over 10 years on our farm and we believe that it does bring a benefit to our farm. It is an insurance policy. A heading timing of a fungicide like Caramba will prevent Fusarium."
For more information visit agsolutions.ca.
May 12, 2016, Ontario – BASF has received registration of Headline AMP, a new fungicide that delivers enhanced disease control and unique benefits of AgCelence for corn and cereal growers. Headline AMP is now available for the 2016 growing season in Ontario and Quebec.
Headline AMP controls key diseases in corn including Northern corn leaf blight, grey leaf spot, eye spot and common rust, according to a press release. Northern corn leaf blight emerges as one of the most economically impactful disease problems, and corn seed genetics are often not a sufficient solution in many growing acres of Ontario and Quebec. In cereals, diseases controlled include septoria, spot blotch and powdery mildew.
Combining two active ingredients, Headline AMP provides corn and cereal growers with multiple modes of action for reduced risk of developing fungicide resistance. Headline is registered as a class three product in Ontario and therefore does not need an aerial permit prior to application.
April 5, 2016, Ontario – Bayer has registered to extend the Stratego Pro fungicide label for corn and spring cereals in eastern Canada, according to a company press release.
The fungicide is registered in corn for early control against key leaf diseases, including Northern corn leaf blight. It can be applied as a preventive disease control measure, or at the early stages of disease development.
The broad-spectrum fungicide delivers disease control through two modes of action: Group 3 (prothioconazole) and Group 11 (trifloxystrobin). On spring cereals, Stratego Pro provides control of septoria leaf blotch, powdery mildew, tan spot, and leaf, stem and stripe rust. On corn, the fungicide provides control of Northern corn leaf blight, grey leaf spot, eye spot and common rust.
Through field testing conducted between 2013-2015, Stratego Pro demonstrated that by effectively controlling labeled diseases under a wide range of disease pressures, the fungicide delivered an average of 6.2 per cent yield increase in corn (vs. untreated). For control of labelled leaf diseases, corn growers can apply Stratego Pro between 7-leaf and early tassel, or at the onset of disease presence, according the press release.
Stratego Pro is registered for ground and aerial application. In addition to corn and spring cereals, Stratego Pro is now also registered for use on durum wheat, barley, oats, rye, triticale, millet, dry peas, lentils and chickpeas.
As farmers in Ontario well know, Gibberella ear rot, or Gib, is an important fungal disease in corn. The same organism, Fusarium graminearum, affects wheat as well, resulting in Fusarium head blight/scab.
The pathogen overwinters in corn and wheat debris and the spores infect corn plants during silking. Indeed, humidity and rain during silking is a huge factor in infection rates, and also temperature (the fungus likes 28 C best). One thing farmers can do to control Gibberella ear rot is avoid corn-corn or wheat-corn rotational patterns. But there are other things farmers should do, says Art Schaafsma, who has been studying the diseases since he arrived at the University of Guelph in 1987.
“After 1986, when there was a huge outbreak, we tried fungicides and we also noticed big differences in the hybrids,” recalls Schaafsma, a professor in the department of plant agriculture at the University of Guelph’s Ridgetown Campus.
“No hybrid has complete resistance and never will, but genetics are important. The turnover in hybrids was high then and it’s still high and we find this to some extent in wheat too. There’s a push and pull between breeding for yield and breeding for resistance. There are certainly corn hybrids highly susceptible to Gib that should not be grown.”
Gibberella ear rot was back with a vengeance in Ontario in 2006, and Schaafsma says it was because the high-yielding hybrids planted at that time had little resistance to the pathogen.
“A good year for yield is a good year for Gib, especially in Ontario,” he notes. “If you needed to locate a bullseye for the disease on a map of North America, it’s southwestern Ontario. In 2006, the problem spilled over into Indiana and other states and the seed companies took notice. They re-examined genetics and weeded out families of hybrids with high susceptibility.”
The window of infection at silking is very narrow, with individual ears susceptible for only about 24 hours. However, Schaafsma notes that with silking happening at different times in different plants in the stand, the total infection time can be a week – and the weather during that week obviously matters. The more days with heavy rain or thunderstorms at the silking stage, the worse the infection risk.
Silking aside, corn can also be infected through wounds in the ear from insect damage (or hail), and earlier damage is worse. European corn borer used to be a big factor in boosting Gibberella incidence in Ontario, but Bt corn hybrids virtually wiped that pest out. However, Western bean cutworm has risen to prominence in its stead and 2014 saw large amounts of Gibberella infection through damage from that pest.
“That year was a huge surprise in the amount of Gib and resulting DON mycotoxin,” Schaafsma says. “Most of the infection was not from the pathogen moving down the silk, but through damaged ears.”
He notes that Syngenta Viptera hybrids have been effective in controlling Western bean cutworm but now resistance to the Herculex gene is becoming apparent. Insecticides are also important in its management, with Coragen and Matador 120EC providing good control with precisely timed foliar application.
Jocelyn Smith, a PhD student in Schaafsma’s department, has been studying the roles of hybrids, insecticides and fungicides in Gibberella control. “Rate timing and testing different products is important,” Schaafsma says. “Smith’s work will give us a wealth of information about that, and it’s also becoming apparent from her work how little damage from insects results in the toxin.”
At this point, Schaafsma and his colleagues advise producers to use a tank mix of Coragen and fungicide. “With fungicide alone, we can only get a 15 per cent reduction in toxin. But with hybrids that have more resistance, combined with fungicide and insecticide, you can expect 70 to 80 per cent reduction of what you would have had through applying nothing.”
Research results show fungicides Proline and Caramba to be equally effective. Schaafsma also notes that strobilurin fungicides are to be avoided in both wheat and corn for Gibberella control, even when mixed, as their application may result in more toxin than if you didn’t spray. Both Proline and Caramba also control corn leaf diseases such as rust, Northern corn leaf blight, grey leaf spot and eyespot.
However, in Schaafsma’s view it’s critical that these fungicides are applied only just after tasseling time – if corn prices are low. “The best timing is when the silks first start to brown,” he explains. “Gib is a weak pathogen and cannot colonize a healthy silk, and doesn’t do well on dead silk, but as the silk is dying, it can infect. So you want to spray on the silks just as they’re turning brown and exposed, two to three days after tassel. Better to apply a little earlier rather than later, so watch the weather.”
He notes that many farmers think the corn is too tall to spray after tasseling, but says, “I’ve done it with my own corn and it’s fine. It didn’t affect yield.” He adds that it’s easier to do it by air at that point, but more expensive, and spraying with a ground rig does a better job anyway.
In terms of overall Gib control plans, Schaafsma advises picking a hybrid with highest yield potential but that also has some resistance to Fusarium, managing Western bean cutworm with insecticide and saving your fungicide for silking time.
“In southwestern Ontario, you cannot afford to neglect DON, as you’ll get dinged when you sell your corn,” he concludes. “A lot of people worry about leaf diseases and forget about the DON. The ethanol plant is not a dumping ground for poor-quality grain and we learned that the hard way in 2006.”
Growers may also want to do an earlier spray for leaf diseases, but that depends on the price of corn.
“The more money you get with your corn, the more you can spend to get the extra few bushels,” Schaafsma notes, “but you can only afford to spray fungicide once a year with low corn prices, and if you spray early, you’ll have a false sense of security.
“The rain during silking can happen, so reserve your fungicide for after tassel. You will still get a lot of leaf diseases but you’ll have less DON in your grain.”
March 7, 2016, Ontario – Syngenta Canada has launched Trivapro, a new three-mode-of-action foliar fungicide that will help growers in Eastern Canada target a broad spectrum of major leaf diseases in corn, soybeans, and cereals.
Trivapro is the first foliar fungicide to feature three unique modes of action – azoxystrobin (Group 11), propiconazole (Group 3), and benzovindiflupyr (Group 7 SDHI), known as Solatenol – with each mode of action providing different activity on labelled diseases, and also contributing to the product’s effectiveness as a resistance management tool.
Syngenta field trials have shown Trivapro offers long-lasting residual control of diseases. Solatenol, a key component in Trivapro, does not metabolize as quickly as other active ingredients. This, in combination with the gradual, translaminar movement of Trivapro, makes it ideal for tassel applications in corn, as the active ingredients remain in the plant canopy to provide extended leaf disease control.
The three active ingredients in Trivapro also allow for a wider window of application. Applied early, its long-lasting residual control helps ensure crops are protected late into the season. However, if applied after the onset of disease, the product’s curative activity helps halt further disease development and protect yield potential.
Trivapro has demonstrated strong activity on challenging corn leaf diseases in Canada, such as Northern corn leaf blight (NCLB), grey leaf spot (Cercospora zeae-maydis), and rust (Puccinia sorghi), according to a company press release.
For wheat, oats and barley, Trivapro controls several major rusts, including leaf rust (Puccinia hordei), stem rust (P. graminis), stripe rust (P. striiformis), as well as Septoria leaf blotch (Septoria tritici), powdery mildew (Erysiphe graminis), and tan spot (Pyrenophora tritici-repentis).
In soybeans, Trivapro controls Septoria brown spot (Septoria glycines), Asian soybean rust (Phakopsora pachyrhizi), frogeye leaf spot (Cercospora sojina), and pod and stem blight (Diaporthe phaseolorum).
Trivapro will be available for purchase in Spring 2016.
A healthy, uniform canola plant stand is one of the keys to establishing high yield potential – that’s generally accepted knowledge in the canola industry. And farmers routinely use fungicide seed treatments to help control the seedling disease complex that cause seed decay, damping-off, seedling blight and root rot.
But how impactful are these seedling diseases, and can other management practices help to mitigate their effects? Those are questions that Alberta Agriculture and Forestry (AAF) researcher Sheau-Fang Hwang set out to understand in a series of greenhouse and field trials from 2007 to 2012.
“Seedling blight has a substantial impact on stand establishment and productivity of canola on the Canadian prairies,” Hwang says. “The causal agent of seedling blight of canola at many sites is Rhizoctonia solani, but Fusarium avenaceum and Pythium species are also important.”
Information from the Canola Council of Canada indicate that seed and seedling losses from these diseases tend to be highest under cold wet conditions or when the seedbed is not firmly packed under dry, cool conditions. Not surprisingly, these conditions are common for canola producers who seed early.
Hwang works at AAF’s Crop Diversification Centre North in Edmonton. In 2007, she initiated two trials to look at the effects of seeding date, seed size, seeding depth and seed treatment fungicides on seedling blight of canola. One study looked at R. solani, and the other looked at F. avenaceum and Pythium ultimum. She wanted to find out how impactful the diseases were on canola; how effective fungicide seed treatments were; and if manipulating seeding date, seed size or seeding depth could reduce seedling diseases.
In the seeding date field trial, soil inoculation with R. solani reduced seedling emergence by 96 per cent in 2007, 98 per cent in 2008 and 91 per cent in 2011. Yield reductions were 81, 87, and 93 per cent respectively, relative to the non-inoculated control.
“Seedling blight of canola caused by R. solani can result in poor stand establishment and severe yield loss in Alberta when soil populations of the pathogen are high and conditions are conducive for infection,” Hwang reports.
She adds seedling emergence was greatly reduced in R. solani inoculated plots for all seeding dates, not only those associated with low temperatures or high moisture.
Inoculation with F. avenaceum reduced seedling establishment by more than 50 per cent each year, with corresponding reductions in seed yield ranging from 20 to 86 per cent over the four years of the study in 2007, 2008, 2009 and 2012. Seeding date did not have a consistent effect on seedling blight in trials inoculated with F. avenaceum.
In treatments inoculated with P. ultimum, seeding in mid-May improved stand establishment compared with early seeding in two of three site-years, and seeding in late May improved seedling establishment compared with early seeding in all three site-years.
“The results indicate that P. ultimum is favoured by cooler temperatures and moist conditions, while F. avenaceum is favoured by warmer soil temperatures,” Hwang says.
The effect of seed size was significant in inoculated R. solani treatments for seedling emergence, plant height, shoot dry weight and root damage severity in the greenhouse trial. Mid-sized seed produced greater seedling emergence, while large-sized seed produced greater seedling height, shoot weight and root damage severity. However, under field conditions, seed size did not affect seedling emergence nor did it have a consistent impact on seed yield.
Similarly, with Fusarium and Pythium species, seed size did not affect seedling establishment or seed yield.
In the field trials, two seeding depths were compared at 0.6 inch and one inch. Seeding depth did not affect seedling emergence or severity of root damage caused by R. solani, F. avenaceum or P. ultimum. However, seeding shallow into a firm, warm, moist seedbed is recommended as a good practice for fast, uniform stand establishment.
Hwang compared Helix Xtra (thiamethoxam + difenconazole + metalaxyl + fludioxonil) and Prosper FX (clothianidin + carboxin + trifloxystrobin + metalaxyl) fungicide seed treatments. In 2008 and 2009, both seed treatments significantly increased seedling emergence and seed yield compared to an R. solani inoculated control treatment. In 2008, untreated canola seed yielded 68 per cent less than the fungicide treatments.
In the F. avenaceum and P. ultimum trials, canola seedling establishment and seed yield were substantially increased by seed treatment with Prosper FX or Helix Xtra. Both fungicides contain metalaxyl, which has activity against Pythium spp. and R. solani. In the trials inoculated with F. avenaceum, Helix Xtra increased yield by 32 per cent and Prosper FX by 38 per cent, although the difference between the two fungicides was not statistically significant. In the trials inoculated with P. ultimum, seed treatment with Helix Xtra increased seedling establishment by 300 per cent and seed yield by 81 per cent compared to the inoculated, non-treated fungicide seed (Prosper FX was not compared).
“These studies emphasize the importance of fungicidal seed treatments in stabilizing canola stand establishment under seedling disease pressure,” Hwang says. “The observation that P. ultimum is more active at early seeding, while both F. avenaceum and R. solani appear to be favoured by warm soils, indicates that the manipulation of seeding date will not substantially improve canola stand establishment and yield. In addition, manipulation of seeding depth and seed size is unlikely to significantly improve seedling emergence under heavy disease pressure.”
Hwang’s research supports the use of fungicide treatments, but also indicates that more than one species is involved in the seedling disease complex. Based on this research, growers should select a broad-spectrum fungicide with multiple modes of action that control Rhizoctonia, Pythium and Fusarium species.
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SeedMaster Crop TourWed Jul 26, 2017
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