ROCKVILLE, Md. (DTN) -- Growers should expect lower-than-average germination rates from their soybean seed next year, experts told DTN.
Much of the country's soybean crop was plagued by unusually wet weather and a long, delayed harvest, which hurt final soybean quality despite overall high production.
"The entire industry is facing less than optimum germination scores on products grown in the Midwest during the 2018 season," seed and agrichemical company Bayer told DTN in an email.
"It's probably going to be a really bad, widespread problem from north to south, with all the wet weather we've had," added Shawn Conley, University of Wisconsin Extension soybean and small grains specialist. "Farmers need to pay attention to this."
Growers should check soybean bag tags carefully for germination rates, calculate seeding rates appropriately and pick the right fungicide seed treatments in the spring, experts told DTN.
BLAME IT ON THE RAIN
Plentiful rainfall in much of the South and upper Midwest allowed many growers to produce bin-busting soybean crops, but it came with a downside. Fungal diseases thrived, and as harvest was delayed due to wet fields, many soybean seeds rotted, sprouted or shattered this fall.
"The biggest player was environmental conditions -- we had a lot of fungal growth and anytime you get fungi on seed, you start getting deterioration as they start feeding on the seed," said Jeremy Ross, University of Arkansas System Division of Agriculture, Cooperative Extension Service soybean agronomist.
The longer mature beans sat in their pods out in the field, the more vulnerable they became to the mechanical stress of harvest and handling, Ross added. "Every time you handle a bean, there is the potential to break the seed coat, so the probability of germination starts to go down each time you move it," Ross said.
Kevin Seward, seed lab director for the Indiana Crop Improvement Association, said soybean seed samples sent to his lab this fall have been visibly lower quality than normal.
"We've seen a lot of pod and stem blight," he said. "You've got some obvious discoloration, some green seed, some darker seed -- just not very eye-appealing seed."
LOW GERMINATION RATES -- AND FALLING
The beans are more than just ugly -- they're underperformers, Seward noted. By late November, the Indiana lab had processed 3,000 soybean samples from seed companies, and they were averaging 85.7% germination, compared to normal yearly averages in the low-90s, Seward said.
The situation is worse in the South, where hurricanes battered soybean fields during an unseasonably warm fall. For the month of November, the Arkansas State Plant Board's Seed Division was averaging only 77% germination, with 37% of the samples running below 80%, said Ross. For comparison, the lab's November tests from 2017 boasted a 91% average germination rate.
But Ross is even more concerned with the results of stress tests that labs often run on soybean seeds, to see how they hold up under sub-optimal storage and growing conditions.
For example, the Indiana and Arkansas labs run a test called "accelerated aging," which subjects soybean seed to high heat and humidity for 72 hours, and then tests their germination rate. The Indiana lab also conducts a "cold germ" test, where soybeans endure a 50-degree-environment for seven days, and are then tested for germination rates.
The Indiana lab's cold germ tests have so far produced an average germination rate of only 84%, where the lab would normally expect to see scores closer to 90%, Seward said.
So far, the accelerated aging test has produced only a 53% germination rate in the Indiana lab, down from rates closer to 75% to 85% in past years, Seward added. In Arkansas, only 57% of soybean seeds on average sprouted after this test, Ross said.
These numbers mean growers should be on alert for germination rates below what they might see labeled on their bag tags, Ross cautioned.
"We know from research that the accelerated aging score is always declining," Ross said. "You can take a sample and test it today and test the exact same sample weeks later and it will have declined. How the beans are stored will affect how fast that accelerated aging number will drop."
SPRING CONSIDERATIONS FOR LOW GERM SEED
The good news is that soybean seed companies always overproduce, in a range of geographies, exactly to prepare for years like this, noted Seth Naeve, University of Minnesota Extension soybean agronomist.
He is hopeful that abundant soybean production will allow companies to discard poorly germinating seeds and still have adequate supplies come planting time. Bayer echoed this optimism in its statement to DTN.
"The majority of our growers will receive soybeans that are tagged 90% germ, meaning the germ score is 90% or better," the company wrote. "On a limited basis, some growers may receive soybeans that are tagged 85%, indicating the germ score is 85% or better."
Ross warned that growers might not have as many soybean variety options available to them as in past years.
"I think there will be seed available, but there will be a smaller percentage of each variety," he said. "Guys might have to fall back to their second, third or even fourth choice."
Ross said he also urges Arkansas growers to ask seed companies to conduct additional germination and stress tests on their seed lots closer to planting season -- or send samples themselves to a state lab -- to get a more accurate handle on what germination rates to expect.
There is no need to stuff your fields full of soybean seeds to avert a germination crisis -- just factor the new germination rate into your targeted final stand calculation, added Wisconsin's Conley. For example, growers who plant 150,000 seeds per acre at 95% germination rates can expect roughly 142, 500 plants to emerge. But if that seed is germinating at only 85% that number drops to 127,500 plants per acre.
"They just need to do the math," Conley said. "Make sure they are still targeting at least 100,000 plants up and growing per acre."
DON'T SKIMP ON FUNGICIDES
If ever growers needed the benefits of seed treatments, this is the year, Conley said. "This is a good reason not to cut at least the fungicide seed treatment out on your soybeans next year," he said.
In the South, university research also supports the use of an insecticide on top of the fungicide seed treatment, Ross added. "Especially on the extremes -- very early or very late planting," he said.
Many companies also offer free replant guarantees if growers opt for a seed treatment; Bayer, for example, offers 100% replant for growers who use the company's seed treatment package.
Don't expect a miracle from these products, Ross cautioned. "What a seed treatment can do is maintain the seed quality you have at that moment -- it will not dramatically increase your germination rate," he said. "If you have poor quality seed, all you really have afterward is poor quality seed with a seed treatment. It won't make a 70% germination rate rise to a 90%."
Emily Unglesbee can be reached at Emily.firstname.lastname@example.org
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