BY: Laura Schmidt, Production Specialist – West, MPSG
Cool, wet conditions prevailed during May and June in Manitoba, resulting in delayed seeding and slow crop growth at the start of the season. By the end of May, most of the province had received more than 150 per cent of normal rainfall. Some areas, like Eden, received more than 300 per cent of normal rainfall. The northwest and Interlake regions experienced a truly challenging spring with many unseeded acres.
With all this rain, seeding windows were tight and cropping plans needed to change on a dime. This showcased the flexibility of soybeans. Seeding dates for soybeans are flexible throughout the month of May and respectable yields can still be achieved into June. In terms of rotation planning, in many fields we can often get away with soybeans-on-soybeans in a pinch, largely since our more challenging soybean diseases aren’t known to occur at great levels in Manitoba. We don’t want to do this every year, especially considering how much phosphorus soybeans remove, but when plans need to change, soybeans have that flexibility.
This early season crunch time and saturated soil conditions meant that rolling operations were tough to sneak in for many soybean and dry bean fields. By the time many folks pulled into their fields with the roller, they noticed those beans were starting to poke through and were at the hook stage and susceptible to breakage. This meant some non-stony fields went unrolled and, in those fields where stones require rolling, post-emergent rolling operations were carefully timed to hit V1 on a hot day when plants were flexible.
These cool, wet conditions were followed by high winds that caused severe sandblasting damage in some regions, leading to reseeding in some dry bean and soybean fields. Fields that weren’t reseeded experienced some maturity delays but otherwise regrew and branched to fill gaps in the plant stand.
The combination of winds, cool temperatures and saturated soils created challenging conditions for timely herbicide applications. In some areas, applications made in windy conditions resulted in off-target movement of herbicides to neighbouring fields. Saturated soils prevented field access in portions of several fields, and cool temperatures meant weeds were growing slowly, limiting herbicide uptake and activity. Despite these weather conditions working against us, many were pleasantly surprised with how effective weed control worked out on their farms this year. The benefits of an effective pre-plant or pre-emergent herbicide program really shined.
For peas, prolonged saturated conditions in several fields resulted in rampant root rot infections by late June. This was especially apparent on fields with a history of peas. Aphanomyces root rot testing was encouraged to help plan for future rotations.
Pea leaf weevils, a relatively new insect pest in Manitoba, expanded their range again this year. Pea leaf weevils have now been confirmed as far east as Stonewall, Man. Thankfully, their populations appeared to decrease this year in the heaviest hit regions in the northwest.
In late June and early July as soybeans reached V2–V3, iron deficiency chlorosis (IDC) symptoms were spotted in many fields with crop yellowing visible from the road. Excess soil moisture, along with soil carbonates, soluble salts and nitrate levels contribute to IDC development. Most fields grew through IDC by V6, with symptoms persisting longer in susceptible varieties.
Following a storm that absolutely swamped the Red River Valley on Canada Day weekend, temperatures increased in mid-July and accumulated growing degree days caught up to normal for most of the province. Humid conditions persisted within the crop canopy, and diseases began to flourish in areas that received more moisture.
Mycosphaerella blight continued to be the most common foliar disease observed in field peas. White mould was found at low levels in most dry bean fields, even those that received timely fungicide applications. In soybeans, Phytophthora root rot symptoms were spotted in many headlands and low-lying areas of fields with soybean history.
In early to mid-August, foliar diseases were common in soybeans. At R3–R4 stages, septoria brown spot was the most common foliar disease (present in 97 per cent of fields), followed by bacterial blight (89 per cent of fields), downy mildew (25 per cent of fields) and frogeye leaf spot (20 per cent of fields).1 At these early reproductive stages, stem diseases were low. Roots were collected at this time and submitted to Yong Min Kim and his team at Agriculture and Agri-Food Canada Brandon Research and Development Centre for laboratory analysis. Results are expected later this winter.
The same fields were surveyed again at R6–R7 stages and stem diseases picked up as plants continued to develop. The most common stem disease at this later timing was white mould, present in 34 per cent of soybean fields surveyed and infecting six per cent of plants within those fields, on average.1 This was closely followed by northern stem canker, which was found in 32 per cent of fields, infecting five per cent of plants in those fields, on average.1
Insect pests remained low overall, with control occurring in a few sporadic fields across the province. The most common pulse insect concern this year was pea aphids, which exceeded thresholds and overwhelmed natural enemies like lady beetles, green lacewing larvae and hoverfly larvae, among others, in some areas. Also, pockets of above-threshold soybean aphids occurred in August. For the most part, natural enemies were able to keep these pests in check.
Root rot-stressed pea fields matured early, ripening in July. Pea harvest began in mid-August but was hampered by winds that caused severe lodging in several fields. Fields were harvested slowly, and yield and quality were overall positive with yield reports ranging from 30 to 85 bushels per acre.
Dry bean harvest began in early September. Some fields that were undercut were caught in mid-September rains. Those windrows took a long time to dry out. Quality was affected with pintos darkening in the swath and sprouting in some fields. Standing crop quality remained positive, with harvest continuing in the third week of September. Yield reports have ranged from 1,700 to 3,000 pounds per acre.
Soybean harvest began in late September. Following mid-September rains, the weather turned hot, dry and windy and by the end of September, soybean crop moisture began to drop below 10 per cent. Yields have been quite positive, with reports ranging from 35 to 65 bushels per acre across Manitoba.
With harvest reports continuing to roll in, there’s a lot of positivity for these crops considering the many challenges they faced this season. To receive agronomy tips on managing some of these challenges, subscribe to The Bean Report, a bi-weekly agronomy newsletter distributed throughout the growing season, at manitobapulse.ca.
1The annual soybean disease survey is a collaborative effort between Manitoba Pulse & Soybean Growers, Manitoba Agriculture and Agriculture and Agri-Food Canada. In 2024, 65 soybean fields were surveyed for diseases. L. Schmidt, D. Lange, D. Kaminski, Y.M. Kim, A. Abdelmagid, J. McCombe-Theroux, T. Buss, E. Bargen, C. Morrison, N. Clouson, A. Farooq and V. Owusu. Soybean foliar and stem diseases in Manitoba in 2024. Canadian Plant Disease Survey, Canadian Journal of Plant Pathology.