Crops: It pays to use soybean seed treatments for early-season aphid protection

Monday, April 5, 2010

Using an insecticide seed treatment like CruiserMaxx Beans can bring a payback of more than one to 1.5 bushels an acre. In stressful years, it could be a lifesaver

by SCOTT FIFE

After more than 105 trials in the last five years, we're convinced that using an insecticide seed treatment, like CruiserMaxx Beans, in soybeans pays off. And, in a particularly tough weather year with heavy aphid pressure, seed treatments could turn into an early-season lifesaver.

CruiserMaxx Beans protects soybeans up to 60 days after planting. Most years, aphids arrive later in the season. In trials conducted by myself and the other Pioneer area agronomists across Ontario and Quebec, the average return is one to 1.5 bushels an acre. That's enough to pay for the insecticide.

We feel that there could be even more upside to using an insecticide seed treatment. In 2009, there was heavy aphid pressure early in the season. The level of protection in the CruiserMaxx Beans plots was excellent. Through the early to middle part of the summer, the difference in plant health between the soybeans treated with CruiserMaxx and those that weren't was significant.

However, a large difference in yield was noticed in only a couple of plots in 2009 in eastern Ontario. I believe this is due to the amount of rain that we received in late July and early August. Late-season rain can make up for a lot of early-season hardship. CruiserMaxx-treated soybeans outyielded non-treated soybeans by five bushels an acre or more in two plots that missed the rains.

My Rockwood-based colleague and fellow Pioneer area agronomist, Laura Sharpe, saw a bunch of fields where the CruiserMaxx-treated soybean strip was basically clear of aphids while the non-treated strip was covered with them.

In fields like that, without early-season protection from the seed treatment, the producer would have had to spray an insecticide. Not only would there have been the cost of the application, the beneficial insects would have been knocked back, too.

Laura says that in trials across Ontario and Quebec in 2007 – a year that was hot and dry with heavy aphid pressure – the trials showed a return of 2.7 bushels an acre from seed treatments.

Aphid pressure seems to be on a two-year cycle. If one year sees heavy pressure, it's likely that the following year aphid pressure won't be as heavy. It's possible that beneficial insects respond by the end of the season and reduce aphid pressure in the fall.

In 2010, areas that had to spray for aphids last year might not see heavy pressure this year. But our research shows that there should still be an economic payback to using a seed treatment.

Research in the lab and in the field has shown that thiamehtoxam, one of the active ingredients in CruiserMaxx Beans, can deliver more robust and vigorous plants. The increased vigour is evidenced by faster emergence, greater plant stands, earlier canopy and increased root mass. According to the manufacturer, this increased vigour may result in higher yields even in situations where there is no visible insect attack. It's important to remember that insecticide-treated seed is non-returnable.

If not for the rain late in the season, I think CruiserMaxx would have paid big dividends in last year's heavy aphid pressure. This may not be a bad year for aphids considering the trend has been for a two-year cycle of heavy to light aphid pressure. However, in the long run, an insecticide seed treatment has paid. In aphid years especially, it could yield an even bigger return. BF

Scott Fife is Pioneer Hi-Bred area agronomist in eastern Ontario.