Insecticide Trials Show Promise in Combatting Springtails

Sidney Sugars' Agriculturist Kathryn Cayko has been hard at work testing methods to combat sugar beet crop damage from springtail infestation.

Springtails are tiny, wingless insect-like hexapods that live in the soil and cause damage to growing beets. They are visible to the naked eye and can be found just under the soil crust. Springtails live in straw during the winter, but feed on both the root and meat of the sugar beet.

It was a "perfect storm" that created favorable conditions for springtail infestation in the 2016 growing season. The cool, wet start slowed down plant growth, long enough for insecticide to wear off. "Part of our seed package comes with an insecticide, but it's wearing off of these plants too quickly," explained Cayko. "It's only active in the plant for about two to four weeks, so when the plant growth is slowed down, the insecticide wears down faster." These conditions, then, are favorable for springtails to feed on the growing beets.

A single female can lay up to 400 eggs, which take about ten days to hatch. The springtail life cycle only requires three molts until it is full grown, and able to reproduce. This means that the offspring from one female springtail can be up to 16 million in just thirty days. "They are laying their eggs in the seeds," Cayko explained, which means the beet barely had a chance to grow at all before it was damaged.

Cayko focused her study on the insecticide as a means to combat the springtails. Beets were planted using specially formulated seeds containing Poncho Beta seed treatment, the current insecticide included in the seed package, and then treated with Counter, an older, more noxious insecticide. Cayko tested seeds containing zero, 75 and 90 grams of Poncho Beta, with Counter concentrations ranging from zero to 8 pounds per acre in special test plots. She conducted stand counts and checked for problems with stunted growth regularly.

In terms of plant production, though Cayko found that overall the test plot soil wasn't optimal, she found that the addition of Counter to the soil produced healthier-looking plants. At a Counter concentration of 3.5 pounds per acre, even the plants with zero Poncho Beta seed treatment produced well. At 8 pounds per acre of Counter, plants produced well regardless of Poncho Beta concentration. "They looked much healthier. They didn't have to overcome so many challenges," Cayko explained, though "there was still a lot of feasting from the springtails." The highest level of Poncho Beta, 90 grams, delayed emergence of the plant and overall, stunted the growth of the beet.

The beets were then processed and analyzed by tons per acre and sugar content. The results showed a clear trend in tons per acre with increasing levels of Counter, and a decrease in tonnage from 75 to 90 grams of Poncho Beta. The sugar content dropped off with higher concentrations of Counter. The best sugar content was found at 3 and 4.5 pounds of Counter per acre.

Overall, Cayko found the best combination to combat springtails was 75 grams of Poncho Beta, which is closest to the current market variety at 65 grams, to 4.5 pound per acre of Counter. Ultimately, the study concluded that high levels of Poncho Beta had detrimental effects on the beets, and relatively low levels of Counter were effective in controlling springtails.

In terms of cost, the addition of Counter will run slightly less than double, at about $1200 an acre at 4.5 pounds per acre, compared to $791 an acre with no Counter treatment.

Because Counter is considered a noxious insecticide, and both the Food and Drug Administration and the US Environmental Protection Agency have limitations on its use in high concentrations, the use of Counter in sugar beets is not ideal. As such, Cayko will repeat the trails in the upcoming growing season in hopes of finding a better alternative. The next insecticide to be tested is Movento HL, a post-emergence systemic foliar application meant for chewing insects, like the springtails.