Late frosts and brutal windstorms so far have been the main contributors forcing the replant of nearly 13,000 acres of sugar beets in the Red River Valley, but now the springtail mite has joined the fray, according to reports released by American Crystal Sugar.
Windstorms doubled up on the area surrounding the Crystal plant in Hillsboro, N.D., plant May 17 and May 24, wrecking some 7,000 acres of beets. Frost followed a late May string of thunderstorms into the valley, killing off most of the balance, along with more winds and some growers deciding to plow under and restart because of pest control issues.
The unusually cool spring weather also has caused the resurgence of springtail mites, which so far have forced sugar beet farmers in the valley to replant about 300 acres, American Crystal Sugar general agronomist Al Cattanach says.
"They've mostly been found in the Hillsboro factory area," he says. "They're scattered around and are causing replanting in small areas."
Overall, he says, the 13,000 acres slated so far for replant is a little above the five-year average. The June 10 replant date for Crystal growers required the damaged acres to be replanted.
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While there are no guarantees there won't be more damaging weather, the springtail mite is a fan of the cool, wet weather that continues in the Red River Valley.
Mighty mite
According to an information sheet provided by North Dakota State University's entomology department, springtail mites are one of the most abundant animal groups on the planet. More than 6,000 species have been described, and an estimated eight times that number remain unidentified.
The springtails live all over the globe, the fact sheet states, occupying diverse habitats that range from old snow banks to deserts and even Antarctica. But they are most abundant in warm, moist environments -- like springtime in the Red River Valley.
"Soil-inhabiting springtails are usually regarded as beneficial to soil health because they assist with decomposition of soil organic matter and can have a positive impact on soil structure," it says. In addition to decaying organic matter, it commonly feasts on spores and fungi, including those of certain strains of potato and sugar beet pathogens.
They are tiny -- almost microscopic in size -- and blind, despite their primitive eyes. Some species are considered to be semi-aquatic, so saturated soils do not present problems for them. They get their name from some species that have evolved a sort of leaf spring under their tails that can fling them as far as 20 times their body length.
In most other Northern Plains cropping systems, they are not a target pest. But because sugar beets are planted fairly early in a more temperate climate, they tend to attack those when they are most vulnerable.
Mark Boetel, an entomologist at North Dakota State University in Fargo, co-authored the information sheet. He says that, historically, most springtail problems have centered around the area between Grand Forks and southern Cass and northern Richland County in North Dakota, as well as the neighboring counties on the Minnesota side of the river.
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Beet fans
"They seem to be most problematic when things stay moist for long periods of time," he says. "The cold temperatures hold back plant development to where the plant can't overcome the extent of the springtail injury, so as the seedlings develop, they just get hammered by the springtails."
Unfortunately for beet growers, the mites tend to thrive in the heavier soils high in organic matter, and they've probably been hammering away at the sugar beets since planting.
"With the spring that we've had where the seed kind of sits and doesn't emerge as quickly as we'd like, the seed germinates very slowly and the springtails capitalize on that," he says. "So when we've got that combination of cold temperatures and wet soils that hold back the plant development, it's almost optimal for springtails," he says.
A behavior recently discovered by NDSU researchers is its penchant for soils where plant debris from previous cropping years has been left on the surface, particularly following either wheat or barley.
"They will be there throughout the season, feeding on fungi and organic matter," he says. "If conditions are the perfect storm, it sets up to where there's plenty of organic matter, some soil moisture and cooler temperatures, we seem to have the worst problems.
They have become increasingly more troublesome during the past 12 to 15 years, he says.
"There's probably a couple things going on," he says. "One is that we are producing higher and higher yields all the time, so there is more organic matter that is produced in the seedbed. The other thing is, since 1993 or 1994, things have been pretty wet. So it could be that the habitat is just becoming more amenable to springtail proliferation."
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Last year was another bad year for springtails. Boetel calls their frequency "more regular than what we would term sporadic."
The good news is that they do not destroy entire fields, he says.
"It's usually patches, anywhere from a half to five acres or so," he says.
What to do
Fighting the mighty mites this year will be an uphill battle. The springtail is expected to feed for several more weeks, Boetel says, while farmers just don't have anything yet to counter them.
"Unfortunately, there's not a good rescue application that they can put on," he says. "Some do try to put on a liquid insecticide over those patches. I don't really recommend that, because you're adding input expense at a high risk of having no return from it."
The best remedy for severe stand loss is to replant those patches with an insecticide, he says.
"Next year, there will be a feed treatment insecticide labeled for that use, as well," he says. "So that will be a fairly convenient way of managing that insect. We've had fairly good success with at-plant granulars, especially with terbufos (Counter) and have found that on the other end of the spectrum of control, a lack of control has been observed with materials containing chlorpyrifos (Lorsban)."
