Post applications to promote soybean growth should be timed for optimal efficacy.
As growers, we often look for the application timing that is convenient, or most cost effective, and can apply multiple products in a single pass. For many of the products on the market, there are recommended timings to optimize their efficacy.
Soybeans will determine their number of branches between V2 and V3. Some growers have done a form of mechanical damage to influence branching at this stage. Rolling is the most common practice, but some have used a form of mowing to also induce branching. As with many plants, soybeans will respond to a stress event with something that directly influences reproduction. Their main goal is to produce seed, so they will do whatever is necessary to fulfill that goal. By V5 soybeans will set the number of potential nodes. This number can decrease if conditions are unfavorable but will never go above that number. Knowing what happens at those two growth stages should influence how we manage our crop.
At V2 and V3 there are only 2 and 3 trifoliates exposed to take up a foliar application. It’s easy to argue that an application timing at that growth stage would not yield a positive result due to the lack of leaf surface area to capture the product being applied. But some growers see it as a very crucial application timing for plant growth hormones or regulators. These products enhance cell division, promote root growth, boost vigor and regulate plant hormones. At V2 – V3 it can also influence branching and growth without the risks associated with mechanical damage.
At V5 many growers are planning their herbicide applications. This presents a great opportunity to add foliar-applied plant growth regulators and foliar nutrition. Most products have proven to be compatible with almost all herbicide platforms, but make sure they are approved on the label. Some herbicides, like ‘lactofen’ burners, can bronze beans and set them back for several days. Offsetting the cosmetic injury of those applications with products that speed up recovery and promote cell division can get those plants to canopy quicker. Most plants are not far from early reproductive phases at V5. Keeping that plant’s growth regulated and foliage nourished will help keep it on track for optimal yield potential. After V5 new V growth stages occur every 3 – 5 days versus the 5 – 7 days it took during VC-V5.
The available products on the market may seem overwhelming, but seeking the advice of a trusted agronomist, CCA or Soy Envoy to help choose a product that best fits your situation or goals may be beneficial. You may unlock the yield potential of your soybeans and make it to the next yield level.