From Minnesota to Mississippi, cool temperatures and soggy conditions are keeping soybean farmers out of the fields. As planting dates slip into May and beyond, some soybean growers may consider foregoing a preplant or pre-emergence herbicide as part of their cultural practice. But experts warn that could be a very costly decision.

According to Bob Hooten, Midwest technical support manager with FMC Corporation, planting windows for corn and soybeans are being pushed into a very tight timeframe. Further planting delays mean more pressure on the grower to get both corn and soybeans planted and to apply a post-emergence herbicide on both, at just the right time, to optimize yields.

Using a pre-emergence herbicide such as Authority First DF, Authority MTZ or Authority Assist from FMC to clean up fields prior to planting soybeans relieves this pressure and will give soybean growers tremendous added flexibility on the timing of their postemergence soybean herbicide application. Plus, the weed control from these products eliminates weeds and competition for resources such as moisture and nutrition, meaning soybeans get a stronger, more vigorous start.

"Time becomes the enemy when planting is delayed," Hooten explains. "Without a pre-emergence herbicide, soybean growers can run out of time and be late with their post-emergence herbicide application and that's going to cost them money in terms of yield." Yield losses can add up rapidly once weeds become established and start out-competing young soybean plants for water and nutrients.

"If a grower leaves Authority out of the tank, the glyphosate application must be made before the weeds reach two to four inches in height," Hooten says. "University research shows that a grower loses three to five bushels per acre from a glyphosate-only program when spraying weeds that are in that two-to-four inch range. Applications past this point have greater yield losses, meaning less profit for growers in a world of $12 per bushel beans."

Figure 1 shows the effect uncontrolled weed growth and untimely glyphosate applications can have on soybean yields, proving the importance of a timely pre-emergence application.

"The yield advantage of using a pre-emergence herbicide on soybeans is huge, but producers can also give themselves more flexibility by putting a pre-emergence herbicide in the tank," Hooten says. "Given today's market for glyphosate, it makes sense to use one of the Authority products as a pre-emergence herbicide-you'll get more value out of your glyphosate and you'll have better yields."

The Authority portfolio of products from FMC Corporation, including Authority First DF, Authority MTZ and Authority Assist herbicides, is the key to optimizing soybean yields when planting is delayed. Authority products provide enough residual effect to allow growers time to apply a post-emergence herbicide on their corn and then apply glyphosate to soybean fields.

The control spectrum of the Authority family of herbicides makes them ideal partners with glyphosate in a soybean weed management program. Hooten explains broadleaves are typically the first weeds to break through a glyphosate treatment. "But with an application of one of the Authority herbicides, soybean growers won't need to worry about those broadleaves - that's the strength of the Authority control spectrum," he says. And because of their dual-action technology, the Authority brands are key for controlling glyphosate-resistant weed biotypes. See the attached fact sheet for more information on the Authority herbicide brands.

Figure 2 shows the efficacy of Authority products in boosting overall soybean yields.

According to Hooten, soybean growers need to act now to protect their acres and yields. "The soil temperatures are still cold enough that putting seed into the ground isn't the next thing on a producer's to-do list," Hooten says. "However, getting the weed control on the ground so that the soybean crop gets a good, healthy start is absolutely critical at this point."

For more information about the complete portfolio of products for soybeans from FMC, please visit