For more than a decade, India has allowed Canada to treat pulse shipments for pests after shipping rather than before. But that may come to an end next month.
The fumigation of pulse pests requires the use of methyl bromide, a pesticide that Canada is trying to phase out because of concerns it depletes the ozone layer. It also doesn't work well in Canada's colder temperatures, leaving pulse producers with few options.
The stakes for the country's estimated 12,000 pulse farms are high. Canada shipped $1.5 billion worth of peas and lentils to India in 2015, accounting for about a third of all pulse exports.
"That's why we're very concerned," said Gordon Bacon, CEO of Pulse Canada.
Bacon said the federal government submitted documents to India in December pressing its case that the risks of Canadian pulse crops carrying pests is minimal because of the winter climate.
"India's message has become much more firm in terms of what their intention is at the end of March, which is why we're much more concerned now," he said.
Pulse producers are now eagerly waiting for a response, with an answer possibly coming in days. But shipments are already being disrupted, Bacon said, with at least one shipping firm refusing to take pulses this past Monday because of the uncertainty.
"It's hugely problematic for the industry when there's no clarity on what the policy will be," said Bacon.
The Indian government could not be reached for comment. But a notice issued by the India Pulses and Grains Association summarized a presentation that the Indian government made last month.
According to the notice, an Indian government official said methyl bromide is the only effective treatment against pulse pests, Indian exporters follow requirements of other countries and importers should do the same, and India shouldn't bear the risks to the ozone layer alone.
The association's notice said the government official also outlined potential alternatives, including the possibility of countries submitting data proving that other treatments are equally effective, a system-wide preventative approach assessed by Indian officials, or cargo pre-inspection. | READ MORE
Why build them? Growers often default to seeding rates of 5 lb./ac. or lower, regardless of seed size or field conditions. These tools will help growers as well as agronomists and seed retailers make more refined decisions.
What do they do? With the target density calculator, users position sliding scales to determine the level of risk for various factors that influence plant stand targets. If weed competition is expected to be very low, for example, the calculator will set a lower target stand. But if spring frost risk is high, the calculator sets a higher target stand to compensate.
The seeding rate calculator has three modes. In seeding rate mode, users input thousand seed weight (TSW), target plant density and estimated seed survival, and the calculator computes the required seeding rate. In plant survival mode, users enter the number of plants per square foot that emerged along with known TSW and seeding rate, and the calculator gives the seed survival rate. In plant density mode, the calculator takes TSW, seeding rate and estimated seed survival to give the number of plants that should emerge.
Because yield potential is known to drop off with stands of around four plants per square foot, the CCC recommends at least six plants per square foot to provide a buffer against season-long plant loss.
Canada’s canola industry has a goal to reach average yields of 52 bu./ac. by 2025. The CCC estimates that improvements in seeding and plant establishment alone can contribute three bu./ac. The tools at canolacalculator.ca can help.
Because of the potential for ongoing problems from this yield robber in the future, there have been significant funding efforts from research programs: One management strategy has been to develop soybean varieties that are resistant to soybean aphids.
“The checkoff in Ohio as well as the North Central region states have put in a lot of investment in developing soybean plants that are resistant to the aphids, but now we have aphids that have overcome that resistance,” said Andy Michel, field crops entomologist at Ohio State University.
To address this challenge, researchers took on the extensive process of sequencing the entire soybean aphid genome to help develop strategies that prevent the spread and increase of aphids capable of breaking aphid resistance. Michel led the effort.
“My laboratory at Ohio State focuses on understanding how soybean aphids are able to overcome aphid resistance in soybean. Through this research, we hope to develop strategies that prevent the spread and increase of aphids capable of breaking aphid resistance. In the course of generating DNA sequences…we were able to sequence the entire soybean aphid genome,” he said. “We now have a really good roadmap for the soybean aphid and understanding all of the genes that are involved that make the aphid such a bad pest for soybean farmers in the north central region.”
The soybean aphid is now the fourth aphid species with a completely described genome and this new information will be a valuable tool moving forward with soybean aphid management. | READ MORE
Central Alberta has some areas of east of Edmonton with high numbers of wheat midge. The population has remained low in much of southern Alberta with the exception of some irrigated fields. Producers should pay attention to midge downgrading in their wheat samples and use this as a further indication of midge risk in their fields.
Over the past several years the field to field variation has been very considerable throughout the province, especially in those areas with higher counts. Individual fields throughout Alberta may still have economic levels of midge. Each producer also needs to assess their risk based on indicators specific to their farm. | READ MORE
There are two confirmed sightings of the brown marmorated stink bug in B.C. One found in Kelowna, the second in Penticton.
“These bugs look for warm wintering sites in the fall and winter, so usually the first detections are by homeowners,” says Paul Abram, a federal research scientist with Agriculture and Agri-Food Canada.
He said though there have been confirmed sightings in the Okanagan, it's difficult to estimate how many of the invasive bugs may already be in the province.
The bugs have previously caused damage in Pennsylvania field crops like sweet corn, field corn and soybeans.
Abram says the province plans to focus efforts this summer on understanding how many bugs are already here and how to manage them. | READ MORE
Researchers at the University of Missouri have determined the mechanisms corn plants use to combat the western corn rootworm.
2016 was a year of extremes for Ontario soybean growers. Incredibly dry conditions in some regions resulted in poor yields or total crop failures in the most extreme cases. In contrast, a dry spring with few diseases, followed by timely rainfall in August resulted in amazingly high yields in parts of southwestern Ontario. Soybean yields are notoriously difficult to predict before harvest so much of the industry was pleasantly surprised at these good yields considering the growing season. Field averages of over 70 bu/ac were reported and yield monitors pushed over 100 bu/ac in the best part of some fields. Current estimates have the provincial average for 2016 at 44.8 bu/ac (with 56 per cent of the reports in from insured growers). This is slightly above the 10 year average of 43.9 bu/ac for those growers. The five year average for the province is 46.6 bu/ac. Soybeans are by far the largest field crop grown in the province with 2.715 million acres seeded in 2016. This was the third largest soybean crop in history. 2014 was the largest at 3.06 million and 2015 had 2.90 million acres.
Higher yields result in greater nutrient removal. Although soybeans take up almost twice as much potassium (K) as phosphorus, both nutrients are essential for soybeans. Factors that limit root growth such as dry conditions and sidewall compaction will reduce uptake. Under dry conditions, roots are unable to take up K from the soil even if soil K levels are sufficient. A soil test is the only reliable way to know if a field is truly low in K or just showing stress-induced potash deficiencies. It’s also important to note that K deficiency symptoms may be an indication of soybean cyst nematode (SCN) feeding on the roots. When taking soil samples, ask the lab to also test for SCN. A spring or fall application with incorporation work equally well to feed soybeans if soil tests warrant fertilizer.
The micronutrient manganese (Mn) is also critical for soybeans. Large parts of Ontario’s main soybean growing areas are deficient in Mn. Symptoms of Mn deficiency is interveinal chlorosis (yellowing). One of the most significant factors affecting the availability of Mn is the soil pH. As soil pH increases, less Mn is available to the plant. Deficiencies may occur on eroded knolls where the pH is higher than the rest of the field. The deficiency is most common on poorly-drained soils, especially on clays and silt loams. High organic matter also ties up Mn. Since only small amounts of Mn are required by the plant, a foliar application of Mn works well to rectify the deficiency. In severe cases, a spray application can provide a five or more bu/ac yield response.
Seedcorn maggot was more of a problem this spring than usual. Seedcorn maggots feed on germinating corn and soybean seeds and young seedlings. Damage can range from minor feeding which delays emergence to seed death. Seedlings that do survive are often severely weakened and may not fully recover. Seedcorn maggot numbers are impossible to predict but a mild winter likely increased populations in the spring of 2016. Maggot feeding results in hallowed out seed with small dark channeling. Flies are attracted to the odour of decaying organic matter that has recently been incorporated, such as freshly tilled soils, decaying plant residue, lightly tilled cover crops, and manured fields. The eggs are laid in moist soil and once hatched begin to feed on germinating seeds. For growers that consistently experience seedcorn maggot damage, an insecticide seed treatment is the only reliable control option. It’s also important to note that treated seed may not give complete protection under extreme insect pressure so higher seeding rates should also be used.
In dry years, some pests proliferate quickly. Spider mite damage was widespread this August. Mites feed on individual plant cells from the underside of leaves leaving stipples. Severe stippling causes yellowing, curling and bronzing of leaves. Spider mites usually start on the edge of the field but wind can carry them to any part of the field. From the road these pockets may look like moisture stress. Fields that are close to neighboring winter wheat stubble, hay fields and no-till fields are more at risk. Foliar insecticide applications were necessary on significant aces this year.
Double cropped soybeans
A number of growers were able to achieve 35 to 40 bu/ac this year, when seeding after winter wheat harvest. One of the reasons double copping is becoming more successful now than 20 years ago is due to higher yielding short season varieties. Plant breeding efforts for northern climates, especially western Canada have resulted in better short season varieties that can be seeded later in the growing season. Fields planted after July 15th or fields that remained extremely dry throughout the growing season were generally not successful.
Soybean variety selection continues to be one of the most important management decisions a grower can make to achieve high yield. The Ontario Soybean and Canola committee conducts performance trials each year across the province. Results from these trials can be found at gosoy.ca. Within a single test yield differences of over 10 bu/ac between varieties are not uncommon. Longer maturing varieties yield significantly more than shorter maturing varieties in most regions. Generally, longer maturing varieties yield 0.4 to 1.0 bu/ac more for each day they take longer to mature in the fall. For fields not intended for winter wheat seeding selecting a longer season variety is a cost effective way to increase yields.
“Are seed corn maggots the kind of pest that wipes out 50 per cent of Ontario’s soybean acreage? No. The overall per cent is relatively small. But, if you are a grower that gets hit with maggots, it’s very significant and very costly for you,” says Horst Bohner, soybean specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs.
Seed corn maggots are small, light yellow maggots that feed on germinating soybean and corn seeds. Because adult flies will only lay eggs in moist, rotting vegetation and larvae need time to do maximum feeding, seed corn maggots are most damaging in cool, wet, slow springs.
Most outbreaks tend to be fairly regional. That said, predicting an outbreak remains extremely difficult.
“The biggest problem with predicting when seed corn maggots will be a problem is that we don’t have a handle on when there will be large numbers of adults. We understand that if seed comes out of ground slowly there is more time for larvae to feed. But why there were a large number of females at one time in a specific region this year, I don’t think anyone knows that. So many of these insects just cycle,” Bohner says.
Once seed corn maggots hit a crop, there is not much a farmer can do but wait to assess damage. Seed corn maggots are difficult to counter because it is virtually impossible to scout for adult flies, and there are no post-seeding pesticide treatment options.
While seed treatments tend to be effective against the larvae, gaining approval for their use can prove to be a chicken or egg scenario: to be approved, one must prove damage has caused a loss of 30 per cent or more of the stand. However, once need is identified it is much too late to counter the maggots and the benefits of a neonicotinoid treatment can only be seen in a replant.
One maggot countermeasure every producer should follow is prioritizing speedy germination and seedling emergence, Bohner says. “Think about proper planting depth, good seeding timing, adequate nutrition and disease management, good residue control. You want to do everything you can to get that seed out of the ground as fast as possible.”
Like many flies, adult seed corn flies are attracted to the odour of decay. Seed corn flies lay their eggs in freshly tilled soil, decaying crop residues, and manured fields. As such, farmers concerned about seed corn maggot infestation may want to consider no-till management. At the very least, farmers should seriously consider opting not to till under cover crops or manure within three weeks prior to seeding.
Farmers who suspect seed corn maggot infestation in their fields should look for widespread and fairly consistent damage across the field, rather than patchy or localized damage. Then, dig up seed to look for obvious physical damage and/or the telltale yellow maggots.
Because the seed corn maggot’s entire lifecycle can occur in as little as three weeks, be aware that a new generation of maggots may be primed and waiting for a second planting of seeds. If seed corn maggots are verified in a field and damage warrants a replanting, consider planting insecticide-treated seed.
It is very difficult to estimate the cost of damage inflicted by seed corn maggots on Ontario fields.
“What typically happens in Ontario is that we have considerable acreage that needs to be reseeded each year, but it’s hard to always know why it needs reseeding. It could be soil borne diseases, insects, cold stress, soil crusting. More often than not, it’s a combination of factors. Seed corn maggots are just part of the overall picture. Replanting costs money and reduces yield potential, but calculating exactly how much of that is due to seed corn maggot is almost impossible,” Bohner says.
“But, I’ll tell you this,” he adds. “Seed corn maggots are frustrating and they are costly. I’ve been doing soybean trials for 15 years. This year, we had a large experiment completely wiped out because of seed corn maggots. So I do know exactly what the farmer goes through when he sees his hard work destroyed by a hard-to-manage pest like seed corn maggot.”
Hormesis refers to an organism’s response to a stressor, where a low dose of the stressor causes a stimulating effect, like increased reproduction, and a high dose is very damaging or lethal. In the case of an insect, stressors could include things like insecticides, temperatures outside of the insect’s comfort range, insufficient food, and insufficient oxygen. But hormetic responses are not limited to insects. They have been observed in many, many organisms, ranging from microbes and plants to humans.
How hormesis actually works isn’t completely understood. “Probably the most commonly cited general theory is the idea of overcompensation. Systems that affect growth and reproduction [in insects and other organisms] are self-regulating and work on feedback mechanisms. So any sort of disturbance to those processes can result in the system trying to correct and overcompensate for it,” explains Chris Cutler, an associate professor with the department of environmental sciences in Dalhousie University’s faculty of agriculture.
For instance, let’s say an insect is exposed to a low dose of a poison that causes its reproductive system to go slightly out of whack. According to the overcompensation theory, its reproductive system will attempt to counteract the problem but will temporarily overshoot its response, leading to higher reproduction. “In a general sense, I think that is kind of how hormesis operates, but we still have a lot of the nuts and bolts to figure out,” Cutler says.
He explains that hormetic responses have evolved over millions of years as mechanisms for organisms to deal with low amounts of stress. So hormesis has always been around. However, it’s only recently that scientists have been identifying such responses as an actual phenomenon. “I think in the past, researchers would often look at [a hormetic] result and say ‘that’s weird’ or ‘that’s an outlier,’ and not really have a word to describe it. Those types of papers have gotten lost in the literature decades ago, but you can find them if you look hard enough,” he notes.
“We’ve documented incidents of hormesis in all sorts of insects, dozens of species across many different families and orders of insects, exposed to many different types of stress, whether it’s an insecticide stress, nutritional stress, temperature stress, radiation stress. So hormesis occurs widely and the concept is now pretty well accepted by researchers, and people are really starting to catch on to the idea.”
Cutler began his research on hormesis completely by accident. “I did my PhD research at the University of Guelph and was working with the Colorado potato beetle. In one of my experiments with an insect growth regulator, which is a more selective or more friendly type of insecticide, I was exposing eggs to the insecticide. I was expecting deleterious effects, like smaller eggs, eggs that wouldn’t hatch, and that type of thing. But in one experiment, I saw that at the low dose the survival and weight of the larvae were higher than in the control. At first I thought I’d got the concentrations mixed up or something. So I repeated the experiment a couple of times and got the same result. And I stumbled on this idea of hormesis, which at that time [about a decade ago] had not garnered much attention at all in insect circles.”
At present, the hormesis research at Cutler’s lab focuses mainly on insecticide-induced responses of various insects to various insecticides. “We’ve been using green peach aphid as a model. It is a widespread insect pest occurring all over the world, attacking lots of different crops, and insecticide resistance is a big problem in that insect,” he notes.
For example, he and his lab have been looking at how this aphid responds to imidacloprid, a commonly used neonicotinoid sold under various trade names, such as Admire. Their research shows that when the aphid is exposed to low doses of imidacloprid, the aphid’s reproductive output goes way up. Cutler says, “We’ve shown this in laboratory and greenhouse experiments where, after a few weeks, the population of the aphids on a plant can double due to exposure to the insecticide that is supposed to kill them.”
In a field situation, many different factors can lead to less-than-lethal doses of insecticide. “Insecticides break down over time. Sunlight will break them down. They are subject to microbial degradation. They are subject to wash-off by the rain. Also, drift can occur, so you may be trying to apply a high dose but the wind takes it so you get a low dose on the plant. And you have canopy effects when you spray so you don’t get as high a dose under the leaves or further down the plant,” Cutler explains.
“So inevitably you’re going to get insects that are exposed to these sublethal doses. And some of these low doses could be hormetic.”
Cutler sees many possible implications of hormesis for agriculture. One obvious one is that insecticide-induced hormesis could make a pest problem even worse by causing pest resurgences and secondary pest outbreaks. Pest resurgence is when the population of an insecticide-treated pest increases rapidly to even higher numbers than before the insecticide was applied. A secondary pest outbreak refers to a rapid population increase in a pest species that had been less important than the target species until the insecticide was applied.
Pest resurgences and outbreaks are often assumed to be due to the harmful effects of the insecticide on the pest’s natural enemies (the predators and parasitoids that attack it). But that assumption isn’t necessarily correct in all cases. Cutler explains, “There have been experiments that have excluded that possibility and shown the outbreak in the field – whether it’s due to aphids or thrips or leafhoppers – is directly due to stimulation from the insecticide.”
The degree to which insecticide-induced hormesis is contributing to pest resurgences and outbreaks in agricultural fields is not yet known. However, it has been documented in many field situations.
Insecticide-induced pest resurgences and outbreaks could clearly have serious impacts on susceptible crops, and could prompt farmers to apply more insecticides, raising their input costs and increasing the risks of insecticide resistance and negative impacts on the environment.
On the other hand, hormesis has positive implications for businesses that rear insects. “Insect rearing is a billion-dollar industry. Insects are reared for a lot of different purposes – for use in research, food for pets, food for people. Honeybees are reared for honey and pollination,” Cutler notes. “I think we can probably harness some of these hormetic principles for rearing these beneficial insects. It has been shown, for instance, that when you are rearing insects like Caribbean fruit flies for sterile insect release (SIR) programs, if you deprive them of oxygen for an hour, that mild stress can prime them to become better at finding mates, become better at emerging, have lower mortality and longer life spans. So this type of preconditioning hormesis can improve the performance of those insects later in life.”
In his current research, Cutler is delving into a number of different aspects of insecticide-induced hormesis, with the help of funding from the Natural Sciences and Engineering Research Council of Canada.
“One of the things we’re doing is looking at this idea of priming, so can mild exposure to one stress condition the insect to deal [more effectively] with subsequent stresses later in life or in subsequent generations? We’re looking at that in aphids.”
Cutler and his lab are also examining the possibility that hormesis may be contributing to insecticide resistance. “We’re looking at a couple of different angles there. We want to see if exposures to low doses of insecticide that may cause hormesis also induce the insect to produce more detoxification enzymes. When you and I or insects are exposed to poisons, we have enzymes that break down those poisons. So, if the insect is exposed to mild doses of insecticide, do we see more of those enzymes?” he says.
“[Another insecticide resistance angle] we’re looking at is whether exposure to mild doses of insecticide can increase mutations in insects. One of the main causes for mutations in organisms is stress. So we want to see if, for instance, hormetic stress that can cause increases in reproduction can also cause increases in mutations in insects such as aphids, and can some of these mutations be for insecticide resistance?”
Cutler is also investigating insecticide-induced hormesis in bees. He does a lot of research on bees and pesticides, so he’s well aware that pesticides are an important risk factor for bees. But he wondered whether insecticide-induced hormesis might occur in bees since it has been found in so many other insects. He recently published a paper identifying evidence in the literature that low doses of insecticide stimulate longevity, learning and memory of bees. Now he’ll be pursuing that idea in his own experiments.
What you can do
Although there is still much to learn about hormesis, especially under field conditions, Cutler offers a few suggestions for practices that could help reduce the risk of insecticide-induced hormesis on your farm.
One practice is to keep an eye on the pest population after pesticide applications. “I suspect that rapidly reproducing pests like aphids, leafhoppers and mites are more prone to outbreaks and resurgences from hormesis, although this has yet to be tested. This might be particularly true for insecticides that degrade to sublethal concentrations more quickly or for systemic insecticides (seed treatments) that work against early season pests but will be at sublethal amounts for most insects after a few weeks.”
Second, minimize drift and ensure good plant coverage when spraying insecticides. “This will minimize exposure of the pests to sublethal concentrations that might induce hormetic responses to stimulate their population growth.”
And third, avoid cutting insecticide rates below those recommended on the label. “As many growers will know, cutting rates is usually problematic because it can ‘encourage’ development of insecticide resistance while increasing the chances of suboptimal pest control. At the same time, exposure to these lower sublethal concentrations could stimulate reproduction of certain pests, possibly creating a double-whammy for the grower.”
“This research represents a breakthrough for addressing a major challenge in agriculture,” said Neal Gutterson, vice-president of research and development for DuPont Pioneer, in a press release. “We have discovered a non-Bt protein that demonstrates insecticidal control of western corn rootworm with a new and different mode of action than Bt proteins currently used in transgenic products. This protein could be a critical component for managing corn rootworm disease in future corn seed product offerings. The work also suggests that bacteria other than Bt are alternative sources of insecticidal proteins for insect control trait development.”
An extremely destructive corn pest, corn rootworm larvae and adults can cause significant economic loss for growers. The current biotech approach for insect control sources proteins from Bt soil bacteria. Field-evolved insect resistance to certain Bt proteins has been observed in some geographies.
Another Pioneer study related to non-Bt insect control, recently published in Scientific Reports, shows how RNA interference (RNAi) can be applied to control corn rootworm feeding damage.
RNAi is a biologically occurring process that happens in the cells of plants, animals and people. By employing the RNAi process, a plant can protect itself by carrying instructions that precisely target specific proteins in pests.
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Canada Young Farmers ConferenceFri Feb 24, 2017
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Central Ontario Agriculture Conference Fri Mar 03, 2017
National Farmers Union - Ontario ConventionFri Mar 03, 2017
Re-Tooling the Diagnostic Toolbox Soils and Crops 2017Mon Mar 06, 2017