Spore of the moment – Being prepared for fungal and fungal-like diseases

Thankfully, the rains have come to soothe our parched lands and breathe new life into our thirsty crops. But as soils become wetter, conditions for the growth of moisture-loving organisms such as fungi become more favourable.

The fungus kingdom is a large and diverse one and includes beneficial species such as those that help in organic matter decomposition and nutrient cycling, as well as disease-causing organisms. In fact, most plant diseases (some estimates put it at around 85%) are caused by fungal or fungal-like organisms. Some of the world’s most devastating famines were brought on by these organisms. For example, the potato blight of Ireland and northern Europe in the 1840s which killed around 1 million people and led to mass migration was caused by a fungal-like organism aptly named Phytophthora (plant destroyer). Some other familiar ones are those that cause diseases such as ascochyta blight (pictured below), anthracnose, downy mildews, powdery mildews, aphanomyces root rot, Fusarium blight, Rhizoctonia and Sclerotinia rots, etc. Typically, the risk of disease increases with moist conditions and high relative humidity, so growers should be on guard when these conditions are prevalent.

Ascochyta on lentil leaflets. Photo courtesy of Saskatchewan Agriculture

So how should we be on guard? Like in boxing, it is not necessarily the hardest punch that knocks you out, it’s the one you did not see coming. So, regular scouting for diseases is absolutely critical. Scouting your fields regularly from crop emergence to maturity allows you to catch disease incidence before it spreads. However, infected plants may take several days before showing visible symptoms, so deciding to take action based on the prevalence of favourable conditions for disease is wise. Fortunately, modern science has given us the tools and knowledge to battle fungal diseases better than farmers could during the Great Famine of the 1840s. Crop rotation, use of disease-free seed, seed treatments, resistant varieties, and application of fungicides can help in controlling these diseases. An integrated approach to disease control is encouraged.

Note that many fungicides are not curative and are only beneficial if applied before infection takes place so spraying before plants are infected is key. Ultimately, spray decisions have to be made based on individual field conditions and economics. Also remember that using multiple modes of action is essential in preventing resistance. Be sure to talk to your SynergyAG rep about disease scouting and suitable products.

-Ikenna Mbakwe, PhD, PAg
Head of Research



tissue testing

Tapping into the benefits of tissue testing

Managing fertility in crop production is not the easiest thing to do. Nobody holds all the pieces of the puzzle. Many times, we are left to play with the pieces left behind after nature has done playing, and our success often depends on how well we play those pieces. When tissue testing was discovered more than 50 years ago, we were graciously handed a prized piece of the fertility puzzle.

The presence of nutrients in the soil is not a guarantee that the nutrient is entering the plant. Several factors such as drought conditions, soil compaction and nutrient fixation may mean that plants are unable to effectively absorb soil nutrients even when those nutrients are there. Only the nutrient that enters the plant is useful in nourishing the crop. Testing plant tissues is the way to know whether or not the plant is absorbing nutrients.

What can tissue testing do for you?

For starters, it takes away the guesswork. Deficiency symptoms of nutrients may look alike and are not always easy to distinguish. Besides, other factors such as frost, water stress, chemical injury or insect damage may present similar symptoms as nutrient deficiencies. Knowing exactly what the problem is can save you a lot of money that would have been spent treating the wrong ailment. Moreover, tissue testing can let you know what remedial actions are needed this season. If deficiencies are determined early, there may still be time to make corrections and avoid substantial yield reduction. Furthermore, results from tissue testing can help you modify plans for next season to ensure that the fertilizer applied at the beginning of the season is adequate to meet crop requirements.

The issue with tissue

It should be noted that tissue analysis shows which nutrients the plant is utilizing at a particular point in time. The underlying principle of tissue testing is that measured levels are compared with standards that have been determined from rigorous experiments that link nutrient contents in tissues of specific plants at different stages of growth with parameters such as final yield and quality. Therefore, it is important that the correct plant part is sampled at the correct growth stage to make results meaningful. For this reason, it is absolutely crucial to follow the guidelines set by the tissue testing laboratory that you plan to use. Your local SynergyAG agronomist can help with tissue sampling as well as interpretation of results.

-Ikenna Mbakwe, PhD, PAg
Head of Research


Managing Herbicide Drift

There are very few things that can turn good neighbourly relations as sour as herbicide drift can. Whether it is on a large farm or in a small neighbourhood, there is no shortage of instances where friendships are strained because someone’s favourite grape tree or tomato plant was killed after a neighbour sprayed dandelions. But herbicide drift is not only a concern for the owner of sensitive crops, it is also a loss to the applicator. The goal of herbicide use is to maximize the amount reaching the target weeds, so minimizing amount moving to off-target areas ensures the herbicide is being applied at the right rates for effective weed control, while protecting neighbouring crops and friendships.

What is herbicide drift?

Herbicide drift is the movement of herbicide at the time of application or soon thereafter, through the air to any site other than that intended for application. There are two main types of herbicide drift: particle and vapor. Particle drift occurs when droplets of herbicides are carried by wind during application, to non-target crops or site. Vapor drift happens when already-applied herbicides evaporate from sprayed surfaces and move from the application site to an off-target area. The potential for vapor drift is high in hot and dry conditions and for volatile herbicides. Drift can result in crop damage and yield loss for non-target sensitive plants, as well as contaminate the environment.

How to reduce herbicide drift

Typically, there is a small window to apply herbicides and the weather doesn’t always cooperate. But although we can’t change the weather, we can adjust for it. A good place to start is to read product labels and select appropriate nozzle type and pressure while also keeping an eye on weather conditions such as wind speed, wind direction and temperature inversions. Large droplets fall faster than small droplets thereby reducing the time the droplets are exposed to wind activity. For example, experiments showed that for a falling height of 10 feet, large droplets (diameter: 1000 microns) required 1 second to land, and drifted 4.7 feet in 3 mph (4.8 km/h) wind, while a foggy droplet (diameter: 5 microns) required 66 minutes to fall and drifted for 3 miles (4.8 km) under the same wind conditions.1 Droplet size can be increased by reducing spray pressure, increasing the size of nozzle opening, and adding suitable drift retardants. Herbicide drift is also influenced by boom or flying height. The higher the height from which the droplet is released, the further the wind can move it away from the target area before it lands. Keep the boom only as high as it needs to be for adequate coverage. It is also important to be aware of plants grown close to herbicide application and to leave an adequate buffer zone between treated fields and sensitive plants.

Large droplets fall faster than small droplets. That’s why the time the droplets are exposed to wind activity is reduced. For example, experiments showed that for a falling height of 10 feet, large droplets (diameter: 1000 microns) required 1 second to land, and drifted 4.7 feet in 3 mph (4.8 km/h)  wind. Meanwhile, a foggy droplet (diameter: 5 microns) required 66 minutes to fall and drifted for 3 miles (4.8 km) under the same wind conditions.1 Droplet size can be increased by reducing spray pressure, increasing the size of nozzle opening, and adding suitable drift retardants.

Herbicide drift is also influenced by boom or flying height. The higher the height from which the droplet is released, the further the wind can move it away from the target area before it lands. Keep the boom only as high as it needs to be for adequate coverage. It is also important to be aware of plants grown close to herbicide application and to leave an adequate buffer zone between treated fields and sensitive plants.

-Ikenna Mbakwe, PhD, PAg
Head of Research


  1. Dexter AG, 1995. Herbicide spray drift. North Dakota State University Extension Service, Fargo, ND.


weed control kochia

Watch out for weeds

‘A weed is but an unloved flower’ – that’s according to popular author and poet, Ella Wheeler Wilcox. I guess she’s right…especially the ‘unloved’ part. They may be flowers, but as long as they are growing where they should not, they are weeds and we don’t love them. We don’t love them, and we don’t want them. They steal the water and nutrients meant for our precious crops, act as hosts to various pests and diseases, and can cause damage to machinery during harvest. That’s why farmers spend a lot of time and resources on weed control. Effective control, however, starts with proper scouting and identification of weed species.

Scouting for weeds is important because that is how to locate weed populations before they spread through the field and cause more damage. Identifying specific weeds also helps to choose appropriate herbicides and best timing for maximum weed control. At this early stage of the season, weeds are mostly harmless-looking seedlings. But make no mistake about it, they can eventually outcompete your crop and can take over your patch of land. Controlling weeds when they are young is more effective than when they are mature and are producing seeds. There are various guides that help to identify weed seedlings. These days there are also apps you can install on your phone that can identify a weed from an uploaded picture. These will be helpful as you scout your fields early in the season.

One weed that you should watch out for is Kochia (Kochia scoparia; see picture below). Kochia is indeed an unloved flower. It was first introduced into Canada as an ornamental plant probably around the mid to late 1800s but has since become one of the most problematic weeds in the Prairies. It’s an annual broadleaf weed that reproduces by seed. Seeds start germinating in early spring, helped by the weed’s tolerance to frost, and may continue to germinate throughout the growing season. It can spread quickly and establish itself as the dominant weed especially in dry and saline soil conditions. In drought, roots can extend as far as 10 feet into the soil in search of water and nutrients. Our crops could definitely learn a thing or two from Kochia especially under the present dry spell. Yield losses can be significant. Losses of 73% have been found in wheat at a Kochia density of 195 plants per square meter.

weed control kochia

Kochia (Photo courtesy of Ohio State University)

The key to effective control of Kochia is to spray early because Kochia is usually one of the first weeds to emerge in the spring and is often beyond the optimal susceptible growth stage when herbicides are normally applied in-crop. Herbicides are most effective when the weed is small. Herbicidal control generally declines as plant size increases. Group 2, 4 as well as glyphosate-resistant Kochia has been found in the Prairies so, herbicide rotation and using tank mixes with multiple modes of action are recommended. Talk to your SynergyAG rep about how to control this and other problematic weeds.

-Ikenna Mbakwe, PhD, PAg
Head of Research

crop nutrition drought Saskatchewan

What do plants need during a dry spell?

The current dry conditions across many parts of the Prairies have farmers keeping one eye on the sky and the other on their crop. Although it is heartwarming to know that dry soils in spring are not a sure sign of crop failure, it is important to be aware of a few things that happen under dry conditions: There is slow movement of soil nutrients towards plant roots so plants are unable to take up nutrients in adequate amounts; soil microorganisms involved in nutrient cycling are inhibited; plants reduce or close stomatal opening, thereby reducing transpiration; this reduction in transpiration limits nutrient transport from the roots to the shoot and results in a low absorption power in the roots. In short, dry conditions cause reduced uptake of nutrients from the soil, and poor nutrient transport within the plant.

What do water-stressed plants look like?

Even before they show any visual signs, the leaf temperature of water-stressed plants will rise. This is because when stomata are closed, energy transfer between plant and surrounding air is limited. Depending on the type of crop, visual symptoms may include dull green colour, curled leaves, droopy appearance, yellowing or browning of leaves, and wilting. By the time visual signs of water stress appear, a reduction in final yield may already have occurred.

So, what can we do?

Growers may be tempted to cut back on input such as fertilizers in a dry spell so as to reduce economic risk. However, research shows that good nutrition is even more important in dry periods. Crops need an adequate supply of macro and micronutrients early in the growing season to develop a strong root system and ameliorate the effects of drought. Some elements have been found to be particularly beneficial in dry conditions. For example, in 1999, south-central Ohio suffered severe drought, and corn yields ranged from 40 to 70 bushels per acre. Certain farmers in the area, however, produced more than 150 bushels per acre. Soil test results showed that these high-yield farmers also had high soil test levels of potassium (K).1 Potassium is critical in dry conditions because the element governs the stomatal opening mechanism and can help plants tolerate water stress. The ability of plants to cope with water stress has also been shown to be enhanced by adequate phosphorus nutrition2. Furthermore, trace elements such as zinc (Zn), copper (Cu) and manganese (Mn) play a role in the structure of many antioxidant enzymes; therefore, a deficiency of these elements makes the plant more susceptible to environmental stresses3.

When the soil is dry, roots are unable to take up adequate amounts of nutrients from the soil, so foliar application of nutrients will be more effective than application of fertilizers to soil. Using a fertilizer with a low salt index becomes even more important in this situation so as to avoid damage to shoots and roots. Furthermore, water-stressed plants have a reduced defence mechanism against pests and diseases, and can easily be outcompeted by weeds. Detecting and dealing with these problems early will give crops a better chance of recovery when moisture becomes adequate. Talk to your SynergyAG rep for product and agronomic advice.

-Ikenna Mbakwe, PhD, PAg
Head of Research


  1. Mosaic Crop Nutrition. Potassium and drought (https://www.cropnutrition.com/potassium-and-drought) Assessed May 30, 2019.
  2. da Silva, E. C., Nogueira, R. J. M. C., da Silva, M. A., & de Albuquerque, M. B. (2011). Drought stress and plant nutrition. Plant Stress5(Special Issue 1), 32-41.
  3. da Silva Folli‐Pereira, M., Ramos, A. C., Canton, G. C., da Conceição, J. M., de Souza, S. B., Cogo, A. J. D., … & Rasool, N. (2016). Foliar application of trace elements in alleviating drought stress. Water Stress and Crop Plants: A Sustainable Approach2, 669-681.
crop nutrient

Early season fertility – Beware of ‘hidden hunger’

Plants need 17 essential elements for growth and reproduction. The main criterion used in designating an element as essential is that it must be required for a plant to complete its life cycle. Elements were accepted into the ‘essentiality’ clique at different times based on when somebody proved they had met the aforementioned criterion. For example, nitrogen was accepted as an essential element in 1804. The newest addition to the family is nickel, determined to be essential in 1987. Crop yield and quality are reduced when plants don’t take up these nutrients in sufficient amounts.

There are 3 ways of diagnosing nutrient deficiencies – soil testing, plant tissue analysis, and visual observation of the plant. Soil testing and plant tissue analysis are quantitative tests that compare nutrient concentrations in soil or plant to the sufficiency range for a particular crop. Visual observation, on the other hand, is a qualitative assessment of indicators such as specific leaf symptoms or stunted growth. Plants can show visual signs when there is a nutrient deficiency. But sometimes they don’t. ‘Hidden hunger’ is a term used to describe a situation in which a crop needs more of a given nutrient but shows no obvious deficiency symptoms. Hidden hunger can only be picked up by tissue or soil testing. If and when visual symptoms do appear, crop yield and quality will already have been reduced and corrective actions may not be effective. If detected early, hidden hunger can be corrected by foliar application of the insufficient nutrient. Foliar feeding normally elicits a quick response from the plant and is particularly advantageous where soil conditions keep nutrients in inaccessible forms.

As seeds become seedlings, it is important to keep the possibility of hidden hunger in mind. One nutrient that is vital at this stage of crop growth is phosphorus (P). Seedlings rely heavily on the P taken up in the first few weeks of growth for crop establishment and yield. Early season limitations in P availability can go undiagnosed but will result in consequences from which the plant will not recover, even when P supply is increased to adequate levels later in the season.

Most soils in the Prairies are low in plant-available P because their high pH and calcareous nature favour the tie-up of P in insoluble compounds. Under this condition, P use will be most efficient when soil contact with fertilizer is minimized by placing the P in a band in or near the seed-row. This allows roots to access and utilize the nutrient soon after emergence. In addition, biologicals containing microbes such as Penicillium bilaii will increase the phytoavailability of P in this kind of soils. Your SynergyAG rep can provide you with a low salt index phosphorus source, as well as natural products that solubilize P from soils.

-Ikenna Mbakwe, PhD, PAg
Head of Research

Dealing with insect pests of seedlings

A termite walks into a bar and asks, “Where is the bar tender?”

This joke right here is a witty reminder that insects love tender plant parts. Seedlings fit the profile perfectly. They are tender, succulent, close to the ground and are easy pickings for a host of insect pests. If left unchecked, these insects have no problem turning our farm into their stomping ground as they feast on our precious crops while singing their version of Weevil Weevil Rock You!

Insects can cause two major kinds of damage to growing crops. First, there is direct injury when insects eat leaves or burrow into stems. Then, there is indirect damage when an insect transmits a disease-causing organism into a crop. Early damage to seedlings produces uneven plant stands, and eventual yield loss. However, the presence of insects in a crop does not mean that there will be significant crop loss. The density of the insects has to reach a threshold that causes major concern. An economic threshold is the insect’s population level or extent of crop damage at which the value of the crop destroyed exceeds the cost of controlling the insect. In other words, if controlling the insect will cost you more money than the damage they’d cause, you should…choose the lesser of two weevils. In canola, for example, treatment is recommended when there is 25% defoliation in the presence of flea beetles.

Keeping insect infestations below significant levels is the goal. Effective control starts with effective monitoring. Every field should be monitored on a regular basis to estimate the populations of specific insect pests. A good understanding of an insect’s behaviour will help to know how best to scout for it. For example, cutworms, can be found first on hilltops because they prefer drier and warmer soils. They will eventually move to low-lying areas when their population increases.

If insect populations exceed economic thresholds, then it’s a good idea to control them using the appropriate methods. Biological control involves the use of the insect’s natural enemies. The northern field cricket (Gryllus pennsylvanicus), for example, is known to prey on flea beetles. In some cases, cultural control of insect pests using good agronomic practices such as effective weed control and crop rotation will help to manage certain insect pests. Chemical control using a good seed treatment or a post-emergent foliar application will also be effective.  So, take the sting out of problems with insect pests and talk to your SynergyAg rep about scouting and suitable solutions.

-Ikenna Mbakwe, PhD, PAg
Head of Research


soil temperature

Soil temperature and its implications for seeding

In many office settings, a request to adjust the temperature of the shared office space can be met with anything from a cold shoulder, to a lukewarm acknowledgement, or a heated argument. Out in the field, however, nature holds the thermostat and we do not get to make that request. So, when late April or early May arrives, our part of the world warms up and farmers in the Prairies prepare to get out into the fields and start seeding. But we also keep an eye on soil temperature – or we should. We should because although soil temperature is affected by air temperature, it is also influenced by soil moisture, soil colour, slope of the land, and vegetative cover which can vary with different soils.

Planting at the optimal soil temperature helps to ensure the best crop emergence. As temperature increases, germination becomes faster and more uniform. Seeding into cold soils can cause seeds to remain dormant and become more vulnerable to soil pathogens, diseases, and predators. This will ultimately lead to poor or staggered emergence and less-than-ideal plant stands. Reduced plant stands favours weed and pests, and also presents staging issues when timing pesticide or herbicide applications. For most spring-seeded crops, soil temperatures warmer than 10°C are optimum for germination. Various crops, however, will germinate at lower temperatures. The minimum soil temperatures needed for seeds of some common Prairie crops to germinate is shown in Table 1.

Table 1. Minimum soil temperatures needed for germination to begin (source: Saskatchewan Ministry of Agriculture)

Crop Soil temperature (°C)
Mustard 2
Canola 2
Flax 3
Wheat 4
Barley 4
Lentils 5
Peas 5
Soybeans 10

Assessing soil temperature is quite simple. First, you have to know the seeding depth of your crop. Then, using a soil thermometer, measure the soil temperature at this depth in a few areas throughout your field. Take two readings – one in the morning, and again in the evening. Take the average of these two temperatures and repeat this process for two to three days to get a multiple day average.

But should you base your seeding decision on soil temperature alone? Certainly not. Research in Western Canada has shown that early planting leads to increased yield because early-seeded crops will utilize available soil moisture better, avoid heat stress during flowering, and can evade the peak pest and disease period. So, it is important to take other prevailing conditions into consideration and plan to seed early. If you have to seed into colder soils, a good way to lower your risk is to use a seed treatment that can improve emergence in cold soils as well as protect the seed against diseases and pests before emergence. Furthermore, because root growth is slow in cold soils, a seed-placed, low salt index phosphorus product will be ideal in boosting root growth in this kind of environment. Your local SynergyAG rep can help you choose the right products.

-Ikenna Mbakwe, PhD, PAg
Head of Research

Minimizing Nitrogen Losses

If there was a throne meant for the king of plant nutrients, I bet nitrogen will be sitting on it, unopposed. The nutrient is by far the most important in crop production. It’s also the most studied, and the most talked about. I’ve even found several songs dedicated to it, from pop to rap…that’s quite cool. What is not cool, however, is the fact that it is difficult to get nitrogen to stay where you want it to – close to plant roots. It seems to always be on the move, change forms and find pathways to leave the soil.  Knowing these forms and pathways is important in minimizing nitrogen loss.

When nitrogen sources such as urea, anhydrous ammonia or manure are applied to the soil, they rapidly convert to the ammonium form. Ammonium (NH4+) is positively charged and can, therefore, be held tightly to the surfaces of soil or organic matter, which are mostly negatively charged (opposites attract; likes repel). But, under favourable conditions, soil bacteria convert ammonium to nitrites and finally to nitrates (NO3). Nitrate is negatively charged and is repelled by the surfaces of soil and organic matter and therefore susceptible to leaching – movement of nitrate below the plant’s root zone by percolating water. Leaching is more prevalent in coarse-textured soils such as sandy soils because these soils have a lower water holding capacity. Nitrate-containing fertilizers, such as urea ammonium nitrate (UAN) and ammonium nitrate, are susceptible to leaching loss as soon as they are applied.

When soils are very wet or waterlogged for a couple of days, soil microbes starved of oxygen will strip the nitrate molecule of its oxygen. With the oxygen stripped from the nitrate, the remaining nitrogen is ultimately lost to the atmosphere as nitrogen oxides and dinitrogen gas. The process is called denitrification. Denitrification rates can range from 5 to 20% of applied nitrogen. Denitrification can be significant when nitrogen is applied in the fall, before a wet spring. It most commonly occurs in heavy clay soils because of poor drainage.

Urea-based nitrogen fertilizer products such as UAN, or dry urea are susceptible to ammonia volatilization if surface-applied and not incorporated. Ammonia is an intermediate form of nitrogen during the process in which urea is transformed to ammonium by urease enzymes. The risk of volatilization loss is high in moist soils and increases with temperature, soil pH and windspeed. Up to 64% of applied N can be lost as ammonia.

Plants take up nitrogen from the soil solution mainly as nitrates and ammonium ions. If you can delay or prevent ammonium from converting into nitrate, you will reduce nitrogen loss by leaching or denitrification. Nitrogen stabilizers can help with that. Some stabilizers can also slow down the conversion of urea to ammonium which allows more time for the nutrient to move into the soil, thereby reducing loss through volatilization. Your SynergyAG rep can help you pick out the right products.


-Ikenna Mbakwe, PhD, PAg
Head of Research





herbicide resistance

When weeds refuse to die

Since the 1940s when herbicides were commercially released, their use has revolutionized agricultural productivity. Without them, weed control in large-scale farming will neither be economical nor practical, and yield losses will be massive. But the innovation was unfortunately accompanied by the increase in the dominance of resistant weeds. One of the earliest recorded cases of herbicide resistance was in wild carrot in Ontario, Canada in 1957. Although science quickly stepped in to develop herbicides with different modes of action, there has been a steady increase in the number of resistant weeds (see global trends in the figure below). Weeds have learned to adapt and science is struggling to keep up.

increase in herbicide resistance
Herbicide resistance is the inherited ability of a plant to survive a herbicide application that would kill a normal population of the same species. Herbicide-resistant weeds have developed genetic resistance to certain herbicide groups, or sites of action. It is important to note that herbicides do not cause resistance in weed species, rather they inadvertently favour resistant individuals that naturally occur within the weed population. Resistance proceeds when the same herbicide, or herbicides from the same group, are applied repeatedly to an area that contains resistant weeds. The susceptible plants die while the resistant ones, favoured by the reduced competition, multiply. With time, only these resistant species will remain and any weed control efforts using that herbicide will be ineffective.

The introduction of glyphosate provided relief from herbicide resistance for 15 years until glyphosate resistance was found in 1996 from rigid ryegrass in an orchard in Australia. Subsequently, several additional glyphosate-resistant weed populations have been identified even here in the Prairies. The increasing risk of glyphosate resistance means that we are in danger of losing the efficacy of one of the most potent herbicides ever produced. Tank mixing multiple modes of action is an important step in preventing herbicide resistance in weeds, and the spring burn-off window is a good opportunity to use a tank mix rather than glyphosate alone.

Management strategies important in preventing herbicide resistance include:

  • use herbicides only when necessary, and use them at the recommended rate
  • avoid using the same herbicide or herbicides from the same group in the same field, in consecutive years
  • use herbicide mixtures that include 2 or more herbicide groups that control the target weed
  • practice crop rotation because different crops allow for a wider range of herbicide options.

Herbicides are very important tools for efficient and cost-effective weed management but their efficacy is an exhaustible resource that can be depleted over time. The present challenge is to manage them in such a way that their usefulness is prolonged while science tries to find a way to beat the constant evolution of resistant weeds. The renowned scientist Robert Pyle once said, “…make no mistake: the weeds will win; nature bats last.” For all our sakes, I hope nature slows down a bit.

-Ikenna Mbakwe, PhD, PAg
Head of Research