Cassandra Tkachuk, Production Specialist – East, MPSG – Fall/Winter (December) Pulse Beat 2021
After a few dry years and another one anticipated, we saw less soil disturbance than ever in spring and it really did help soils retain moisture. Most farmers set out to plant early to access residual soil moisture out of fear that the taps might not turn on. Temperatures warmed up earlier than usual, tempting pea growers to plant in early April with some going for it in the second week. Heavier soils were more friable than ever and sandier soils were more fragile than ever. Rapidly drying topsoil forced farmers to push seed deep. And in some cases, the moisture line dropped below the furrow.
Delayed emergence, uneven plant stands and a wide range in plant development after emergence were common. Much of this stemmed from variable seed depth and reduced germination from the lack of moisture. Pulse and soybean crops in June had the widest variability in development that I have ever seen, with a spread of one to two development stages more than usual for each crop.
We had late spring frosts for two nights in a row on May 26–27 and May 27–28. The first night of frost impacted most of agro-Manitoba with temperatures ranging from -1°C to -8.9°C and remaining below zero for up to 11 hours. The northern Interlake region was hit the hardest. The second night was less severe by comparison (0°C to -4.9°C), hitting mainly the southern half of agro-Manitoba. Pockets in the east and west that had up to six hours of frost. Peas and faba beans were resilient to frost damage and dry beans hadn’t emerged yet, but soybeans were starting to poke out of the ground and some damage was done. Thankfully emergence was incomplete, so some plants were still safely underground.
Heavy winds blew soil into furrows and crop residue into clusters, increasing seed depth and hindering emergence in some spots. One mid-June windstorm hit parts of the south-central region pretty hard. We discarded our wide-row dry bean variety evaluation trial at Winkler due to wind damage and edible bean plants were ripped from the ground in a commercial field nearby, reducing plant stand by 30%. The same storm tattered a large swath of soybeans at the west end of a field to the point that they looked like they were gone. But they were miraculously regrowing within the week and the field bounced back as if nothing ever happened (Figure 1).
July was a brutally hot month with 16 days above 30°C. These hot temperatures induced a lot of crop stress during critical developmental stages. Plants routinely flipped their leaves and closed their stomata, meaning less photosynthesis took place and plants were deprived of the sugars needed for growth and yield. Prolonged drought stress caused shorter plants with less leaf area (putting more into below-ground growth than above-ground), abscission of leaves, shortened vegetative and flowering periods, aborted flowers, pods and seeds, smaller seed size and early maturity. And sadly, drooping field pea plant tops at the end of June. Even peas that typically thrive in dry conditions have their limits.
Rainfall systems were infrequent and selective. One area would get a nice soaking rain and huge sections of the province would get nothing. Many areas seemed to be operating on one good rain per month until August. Widespread, plentiful rains finally fell in mid-to-late August that benefitted R6 soybeans in Westman, but it was unfortunately, too late for the R7 soybeans in Eastman
There were reports of nodulation failure in soybeans and peas, likely caused by high residual nitrate levels detected across the province (more on page 47), inoculant failure, or in the odd case, root rot. Options were limited, but rescue nitrogen was recommended if there were also signs of N-deficiency and good yield potential of the crop. Interestingly, we saw several large soybean nodules reported by research to be more susceptible to drought. Symptoms of potassium (K) deficiency were also common in sandy fields and exacerbated toward the end of the season as pod demand for K increased.
Distinctive pest issues in 2021 included:
- a newly-identified case of soybean cyst nematode in the R.M. of Thompson (making a total of five rural municipalities), but this time with visible cysts on the roots (more on page 39)
- our first case of the famously herbicide resistant noxious weed, Palmer amaranth, found in a black bean field in the R.M. of Dufferin
- pea leaf weevil confirmed at more locations further from the western edge of Manitoba (more on page 49)
- lygus bug damage to edible bean seed at various locations across the province and
- very low root, stem and foliar disease pressure except for fields with tight crop rotations.
In mid-September, there were a few unique reports of soybean plants remaining green. Fields had either the odd green plant, small patches or a large section of green toward the headlands, where the rest of the field was harvest- ready. In one case, plants had prolific growth of buds and flowers, especially in low spots. Affected plants had few to no pods and didn’t have any hope of contributing to yield at that late date. There were also a couple of edible bean cases around the same time, where entire fields stayed green with reduced pod set. These issues appear to be strongly linked to drought conditions during flowering and the subsequent shift to better moisture in August that triggered regrowth. We still don’t know exactly what was causing this, but we are considering the greenstem disorder and male sterility as potential causes (more on page 42) and we are investigating viruses.
Crop yields were highly variable and surprisingly great in some areas of the northeast, central and western regions. Soybean yields ranged from 15–45 bu/ ac overall. There were lots of soys in the 30–40-bushel range, 15–20 bushels were from extremely dry, sandy soils and >35 bushels were a product of better rains and heavier soils. Pea yields ranged from 15–50 bu/ac with lots of fields in the low 40s. And across all market classes of edible beans, yields were mainly at 1,000–1,200 lbs/ac in moisture-limited areas, around 1,600+ lbs where moisture was better and ranged anywhere from 500–2,000 lbs overall.
Despite the hardships, I have to say these crops are tough. Some locations received almost no rain all season and the plants still grew and produced pods — even water-loving soybeans that have never really seen a drought like this during their short history here.
For more specifics on the past growing season, we have a great catalogue of Bean Reports at manitobapulse.ca/the-bean-report. You can also sign up on the right side of this page to receive this timely newsletter.