Keep Diseases and Insects at Bay to Protect Soybean Yields
Japanese beetle on soybean leaf
For high-yielding soybeans, it’s crucial that growers are in tune with their plants’ growth stages. According to Iowa State University Extension, soybean yield management strategies are most effective when timed with the stage in which potential yield is most affected.
For example, let’s look at the R2 growth stage, a particularly critical growth stage for soybeans. The University of Wisconsin explains that by this time the plant should be well on its way to maturity, having accumulated about 25% of its mature dry weight and 50% of its mature height, as well as produced 50% of its total nodes. Plants will increase dry matter and nutrients frequently at this stage, initially in the vegetative plant parts (leaves, stems, petioles and roots) but later in the pods and seeds. Foliage protection is key.
It’s during this growth stage that plants are setting a lot of flowers, says Agronomy Service Representative Nick Groth. The grower’s job during this time is to protect those flowers to ensure they’re turning into healthy and productive pods.
How can you protect your soybeans?
Regular scouting is an important strategy to stay on top of disease and insect pressure, which can cause great damage during the critical R2 growth stage.
White mold is one costly disease that is particularly prevalent in fields with high yield potential. This is because practices such as high plant populations, narrow row spacing, and varieties with an early canopy closure are frequently used in high yield potential situations and are conducive to white mold development. While fungicides can help protect soybean plants from diseases, Iowa State University Extension cautions that applications after R3 will likely not be effective at controlling white mold, urging growers instead to make the application earlier at a R1 or R2 timing.
Fields should also be scouted for insect pressure during this growth stage as well, as pests such as soybean aphids and bean leaf beetles can quickly reach economic thresholds and require action. Soybean aphids are a particularly unpredictable pest. While they once followed a reliable every-other-year pattern, Dr. Kelley Tilmon, associate professor of entomology at The Ohio State University, says soybean aphids can actually emerge every year if conditions are favorable. To stay ahead of a potential problem, University of Minnesota Extension recommends scouting through R6.5, sampling at least 20-30 plants per field and monitoring infected fields at least every 7-10 days.
A fungicide-insecticide tank mix can help growers manage both diseases and insects while saving time and fuel costs. Two products we recommend in soybeans for the R2 growth stage are Miravis® Neo fungicide and Endigo® ZC insecticide. Miravis Neo helps soybeans reach full yield potential with 3 active ingredients –propiconazole, azoxystrobin and Adepidyn® technology – that provide improved preventive and curative control of key diseases, including white mold suppression. Endigo ZC delivers extended residual control of key foliar insect pests in soybeans such as soybean aphid, Japanese beetles, stink bugs and bean leaf beetle, resulting in higher potential yields.
There are plenty of diseases and insects that threaten soybean plants, but with strong products to protect them, plants will be one step closer to maxing out their yield potential.
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