flax Archives - Manitoba Crop Alliance

What exactly are corn, sunflowers and flax dealing with in this standing water and saturated soils?

Morgan Cott on July 2, 2026

By Morgan Cott, Agronomy Extension Specialist – Special Crops, Manitoba Crop Alliance

The crops we grow and work with in Manitoba do not generally do well in extended periods of flooding or saturated soils. Roots and growing points need oxygen to develop, so plant growth is delayed in these conditions. Disease development is also escalated in wet, hot, humid conditions, so that is another impending threat down the road.

Timing has not been ideal for corn. If you have puddling or any degree of flooding or standing water, corn at V5 or smaller is at vulnerable staging for survival. The growing point remains below ground until V6 and I think most corn crops were moving into the V6 at the time of the June 23 heavy rainfalls. It can be very stressful for a crop to have excessive moisture arrive as the growing point emerges from underground. No matter where the growing point is in the plant, if it is below the waterline, conditions become anaerobic and it cannot “breathe.” While photosynthesis can still be occurring in parts of the plant above the waterline, root growth is restricted below the waterline and all nutrient and water intake is hindered.

At this point in the season, I want any standing water to recede quickly and I also want the air temperature to stay mild during that period so there is no rapid growth or additional stress. Already, a week after the heavy rains, there is very visible rapid growth in corn fields across southern Manitoba.

Partially flooded corn field. Photo by Eric Tyschinski, MCA summer student.

Sunflowers are equally stressed in anaerobic conditions. Even though their water use is very high, if the plant cannot breathe, it cannot grow. In these times of excess moisture, we don’t want the crop to be in standing water for longer than three days, and cloudy, mild temperatures are best to keep other stresses to a minimum. Unfortunately, sclerotinia development is a significant threat in these conditions, and as the fields dry out, humidity will be high and conditions will be favourable to development, so basal and stalk infections could become severe this year. Keep an eye on stressed sunflower fields to ensure new growth is still coming and plants are still photosynthesizing.

Effects of excess moisture in flax are exactly what we would guess: it has a low tolerance to severe stresses and will not survive long. The estimate for flax in standing water is about three days before the crop really starts to struggle and yield will be affected. Fortunately, stem root diseases are only a minor issue in flax crops and the wet soil conditions won’t affect this crop as much as it would others with regards to disease intolerance.

With all crops, check for new growth regularly to determine how efficiently the crop is still working and developing. Dig up a few plants to assess root growth. In saturated soils, roots don’t need to grow downward to find moisture, so the benefits of a strong root system later in the season might be diminished. Root health may suffer, which will be identifiable by the colour of the root. These are all good assessments to continue until the soil water subsides, the field starts to dry out and the crop can grow as intended.

Partially flooded flax field. Photo by Eric Tyschinski, MCA summer student.

Helpful Resources:

The Impact of Mid-Season Excess Moisture
Purdue University: Effects of Flooding or Ponding on Corn Prior to Tasseling

New, promising flax varieties for Manitobans

Morgan Cott on March 4, 2025

Manitoba flax farmers (and upcoming flax farmers) will soon have full access to a new flax variety, CDC Esme. As of spring 2025, CDC Esme is available to seed producers across the province, as long as they have been able to access it from seed dealers.

As stated in the Secan Technical Bulletin for the variety, CDC Esme is a large seeded, high yielding brown seeded flax variety with good lodging resistance and late maturity. Esme proves to be a strong yielder in MCVET trials across several site years, with oil content similar to check varieties. Statistics show an average of 2 cm shorter than CDC Glas, which is a beneficial trend in Manitoba, where farmers are trying to reduce flax straw and residue.

Dr. Bunyamin Tar’an and his team at the Crop Development Centre in Saskatoon developed CDC Esme and have several more flax lines that have strong potential for registration on the Canadian Prairies. Most recently, Tar’an had an experimental flax line that has been recommended for registration via Canadian Food Inspection Agency. This line, currently named FP 2608, will undergo a registration process and could likely be available for seed production in the next two years.

FP 2608 has been a promising yielder in the Flax Co-op trials performed in Manitoba and is a consistently strong yielder. It appears to be quite tolerant of pasmo infections in past reports, and oil content and yield has been ranked very high amongst other varieties and lines. Tar’an has noted that FP 2608 had considerably strong performance in the more northern Co-op trials in Manitoba, which perhaps displays its ability to thrive in less diverse rotations.

MCA is very proud of our relationship with Dr. Tar’an and are very excited about his future work in flax breeding. Some new work that he is working on includes “Accelerated Breeding Strategy for Flax Improvement” which looks at developing inbred populations in a shorter term than is current reality. This would mean that future varieties could potentially be brought to the market more quickly and readily than they have in the past. Another highlight of Dr. Tar’an’s work is that he is committed to reducing straw content while increasing seed production in future varieties. He has had to delve back in time and use flax’s wild ancestor, Linum bienne. By using historial genetics, Tar’an can benefit by breeding their old, shorter varieties with new modern varieties that have bushier plant structure, therefore, higher yielding qualities and improved harvestability.

Flax can have a strong future on the Prairies and Manitoba Crop Alliance is supporting that possibility for our farmers. It is a crop that requires patience and consideration, which we believe Manitoba farmers are great at and can help us solidify the flax industry on the Prairies. Discussions with farmers that have been growing flax successfully for several years tell us that it is one of the top most profitable crops on their farms because they are willing to put an extra effort in to the crop. In this case, it doesn’t mean inputs, directly. These farmers are treating flax like the special crop that it is; slowing down and using precision and sustainable practices to support the germination of a tiny seed into a beautiful and profitable crop.

Please contact the MCA’s Agronomy Extension Specialist for Special Crops if you are considering growing flax or currently work with flax and are interested in more agronomic information.

Research on the Farm: Flax Plant Population Trials Summarized (2022 – 2024)

Morgan Cott on February 5, 2025

Manitoba Crop Alliance’s Research on the Farm program looks at common agronomic, crop-specific concerns on field-scale, replicated trials in commercial fields. 2024 saw the flax plant population trials completed with 19 site-years of data.

The objective of this specific trial was to quantify the agronomic and economic impacts of various plant populations in flax production in Manitoba. A lack of genetic improvements in flax varieties in recent years raises the question of whether farmers can either increase or decrease their planting populations with improvements in quality and/or yield. Farmers took to the field to make that final decision.

Figure 1: MCA Research on the Farm: Flax Plant Population Trial locations from 2022 – 2024

Tone Ag Consulting performs MCA’s Research on the Farm trials in all 6 of our crop-types. In this specific trial type, they are helping the farmer with planting and harvest of the plots, plus taking some key information during the growing season. This includes soil sampling in the spring followed by growth stage notes and precipitation data during the season.

Table 1: Three-year summary of flax plant population trial for 19 site years. Zero of the 19 site-years contributed statistically significant yield differences which would provide profit for the farm, based only on seed prices.

When looking at this full data set, it doesn’t necessarily give a farmer the details they are looking for. At the end of the day, they want to know the ROI for each treatment, which includes spring seed costs and flax prices off the combine. Simply stated, if the “high” planting rate outyielded the “low” and “check” planting rates, it may have only been marginally, therefore the higher seed cost of planting at a high rate was likely not the economical choice.

Table 2: Three-year economic summary of flax plant population trial for 19 site years. Net profit per acre was calculated using estimated seed cost in spring 2024 and contract pricing in fall 2024.

According to this small data set in Manitoba, farmers appear to seed on the heavier side of what is necessary for their management practices. Experience determines what works best on any given field, in addition to being mindful when it comes to general flax management. It is a special crop and requires a certain amount of care and precision to achieve profitable yield, but it absolutely is realistic in Manitoba.

Planting populations are reasonably simple to set up on-farm and MCA recommends farmers make the effort to periodically do this same testing. 2022 and 2023 were dry years in areas of Manitoba and 2024 had much more precipitation. It is important to continue to collect data in years of varying precipitation to determine planting rates that work better on your farm in all environments.

Tone Ag Consulting carries out MCA’s ROTF trials in all six of our crop-types. They assist the farmer with plot planting and harvesting, then capture key information throughout the growing season. This includes soil sampling in the spring, followed by growth stage notes and precipitation data during the growing season.

Holcus Spot

Morgan Cott on November 8, 2024

What is holcus spot?

Holcus spot on corn leaf

A bacterial leaf disease affecting mainly corn crops, though it can overwinter in both monocot and dicot species. Holcus spot begins as a water-soaked spot on lower leaves and develops into small (1/4 to 1/8 “ in diameter), circular to elliptical, white to tan lesions. Lesions commonly develop a brown margin and sometimes a light halo is visible around the lesions. In severe infections, holcus spot can cause significant lesions on plant leaves, though it is more common to have minor spotting, covering less than 5% of a single leaf’s surface.

Conditions for Development

Holcus infections follow typical Manitoba spring conditions. This includes high winds and heavy rains, followed by extended moisture and warm summer temperatures (24C – 30C). The bacteria is interesting because it infects the leaf via wounding, but it doesn’t need a wound for development. The pathogen also does not spread from an infected leaf to a healthy leaf, as in many other leaf diseases.

Disease Management

The holcus spot pathogen lives and overwinters on crop residues. Best management practices to gain control of the pathogen are crop rotation and tillage. As a bacterial pathogen, fungicides will have no effect on the disease.

Fortunately, holcus spot affects a very small area of each infected leaf and photosynthesis of the green leaf material is still very effective. This is a concern in more disruptive leaf diseases or killing frosts that affect large areas of each leaf and photosynthesis is allocated to a small area or none at all. As a result of the small area affected, yield is not penalized and holcus spot is more of an aesthetic disease than a concern for farmers.

Don’t get confused…

Holcus spot infections are relatively uncommon. It is easy to see them and be unsure of what it means because lesions are most often minute and don’t draw attention.

In the rare occasion that the disease does grab attention, lesions can be confused with drift of a contact herbicide, like diquat (image below), or fertilizer burn. Key tips to determine if it could be fertilizer injury would be to ask the farmer or applicator if anything was applied recently or in the sprayer tank. If there is a possibility of herbicide drift, there will be a clear pattern in the area that would have gotten “hit”. The lesions would likely be worst along the outer rows and lessen the further into the field you look. Early in the season, injury would not grow with the plant and new leaves would be injury-free.

Diquat drift on corn leaf

The Impact of Mid-Season Excess Moisture

Morgan Cott on July 3, 2024

It is well-known that spring weather in Manitoba is unpredictable. Farmers endure drought conditions one season and excess moisture the next, never knowing for sure what is ahead. These dubious conditions make crop planning particularly difficult because no one knows what extremes of moisture crops may or may not have to grow through that season.

Generally, crops should endure excess moisture fairly well in early summer, when they are actively growing vegetatively, and environmental conditions are usually conducive to evaporation. The growth curve is quite steep during this time, especially in the large-sized crops like corn and sunflower and their water uptake is generous if conditions are good. Flax is not going to be a crop that tolerates “wet feet,” and it will be evident if it is in standing water for extended periods.

Corn

Corn that is past V6 staging has the growing point above ground, so flooding at this stage isn’t quite as detrimental as it would be at earlier stages. Remember that where there is standing water, there is no oxygen exchange and living cells cannot survive without it for very long. Ideally, conditions do not get too hot (crop stress) and evaporation and/or water drainage can happen quickly. Depending on how many times the flooded areas have been flooded this season, this influences the ability of the crop to “bounce back.” Root death is possible in this scenario and warm, dry soils will be required to generate new root growth. New root growth is possible in corn in these situations, but the new growth will extend horizontally, which leads to a few implications with nutrient uptake and plant stability.

In younger plants, V5 or smaller, being waterlogged for four days would be a maximum time span to survive and recover. It is harder to determine what that is for larger plants that are growing much more quickly, especially if there have been multiple heavy precipitation events that have left fields saturated and/or puddled. It is also exceedingly difficult to determine what nitrogen losses may be, and even more so when top-dress applications have occurred recently. At this stage and in the days ahead, it would be very important to keep an eye out for nitrogen deficiency symptoms. Corn nitrogen uptake is about 60 per cent of total uptake from the V8 to silking stages, so losing access to nitrogen via leaching or denitrification could seriously impact yield.

Sunflower

Sunflowers are growing rapidly in July and moving quickly into the reproductive stages. At this time, the crop can be using up to ¹/₃ inch of water each day. It is hard to believe that with this excessive water use that the crop wouldn’t manage saturated soils very well, but the roots do still need to breathe. Photosynthesis also slows down while stomata remain open in wet conditions, which slows plant development. In flooded conditions, sunflowers may have a tolerance for about three-plus days in an anaerobic environment. During those conditions and following, crop recovery is better with cloudy and cool-warm weather rather than hot and sunny weather.

Sunflowers are also very susceptible to stalk diseases during this vegetative growth, including sclerotinia basal rot. Sclerotinia infections can occur anytime between early vegetative stages through to seed fill and generally need precipitation to spread their spores. It is an important consideration for farmers and agronomists and recommended to know the high risk of disease that the crop carries in wet environments.

Flax

Flax has the lowest tolerance to flooding of the three specified crops. It is a small, shallow-rooted crop that does not adapt well to extreme conditions, nor does it have a need for high amounts of water to grow. If it remains in standing water for longer than three days, flax will become stunted, yellow and there will be a high risk of yield loss.

Flax requires the bulk of its water during flowering and seed fill, at roughly 0.28 inches/day. It is also known that dirty (weedy) flax fields use water much less efficiently than clean flax fields. The one benefit to flax in wet fields is that it is not as susceptible to stem diseases as most other Manitoba oilseeds, therefore wet conditions are not a matter of concern with regards to yield or quality loss due to disease.