Watch the Germs

Watch for lower-than-average germination rates on soybean seed tags this spring.

Much of the country’s crop was plagued by unusually wet weather and a long, delayed harvest. While there appears to be no shortage of seed supply, seed companies are warning that the entire industry is facing less-than-optimum germination scores, particularly on products grown in the Midwest during the 2018 season.

Experts are urging growers to calculate seeding rates carefully and use the right fungicide seed treatments.

BLAME THE RAIN

“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,” says Jeremy Ross, University of Arkansas soybean agronomist.

Kevin Seward, seed lab director for the Indiana Crop Improvement Association, says soybean seed samples sent to his lab last fall were visibly lower quality than normal.

“We’ve seen a lot of pod and stem blight,” he says. “You’ve got some obvious discoloration, some green seed, some darker seed--just not very eye-appealing seed.”

FALLING RATES

The beans are more than just ugly, they’re underperformers, Seward notes. 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 says.

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 Seed Division was averaging only 77% germination, with 37% of the samples running below 80%, Ross explains. 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 run to see how the soybeans will hold up under suboptimal 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 50ËšF environment for seven days and are then tested for germination rates.

The Indiana lab’s cold germ tests last fall were producing an average germination rate of only 84%. The lab normally sees scores closer to 90%, Seward says.

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 adds. In Arkansas, only 57% of soybean seeds on average sprouted after this test, Ross reports.

These numbers mean growers should be on alert for germination rates below what they might see labeled on their bag tags, Ross cautions.

“We know from research that the accelerated aging score is always declining,” Ross says. “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.”

PLANTING CONSIDERATIONS

The good news is soybean seed companies always overproduce, in a range of geographies, exactly to prepare for years like this, notes 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.

The Crop Science Division of Bayer confirmed that practice in email correspondence. “The majority of our growers will receive soybeans that are tagged 90% germ, meaning the germ score is 90% or better,” a company spokesperson explains. “On a limited basis, some growers may receive soybeans that are tagged 85%, indicating the germ score is 85% or better.”

Ross warns that growers might not have as many soybean varieties available to them as in past years. “Guys might have to fall back to their second, third or even fourth choice,” he says.

Ross also urges growers in his state to ask seed companies to conduct additional germination and stress tests on their seed lots as the planting season draws near. He says growers can also send samples 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, adds Shawn Conley, University of Wisconsin Extension soybean and small grains specialist. 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 says. “Make sure they are still targeting at least 100,000 plants up and growing per acre.”

THE NEED TO TREAT

If ever growers needed the benefits of seed treatments, this is the year, Conley says. “This is a good reason not to cut at least the fungicide seed treatment out on your soybeans next year,” he adds.

In the South, university research also supports the use of an insecticide on top of the fungicide seed treatment, Ross adds.

But, don’t expect a miracle from these products. “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 says.

[PF_0219]

Copyright 2019 DTN/The Progressive Farmer. All rights reserved.