Corn plants need boron throughout the growing season. The uptake curve for the micronutrient is pretty linear from emergence to black layer, but making boron available in the ear later in the season, where it plays an important role in sugar movement and developing kernels, can be difficult.
The challenge, says AGRIS Co-operative senior agronomist Dale Cowan, is boron’s lack of mobility within the plant. He notes that many growers apply boron as part of a starter fertilizer program and also add the nutrient at sidedress, a practice that Cowan says has consistently demonstrated a yield bump of five to eight bushels on sandy loam and loamy fields.
But Cowan thinks growers could see an even larger yield increase from boron. On this episode of the RealAgriculture Corn School, he notes that tissue testing shows the nutrient has considerable ability to move up through the plant, but doesn’t have the same capacity to move downward later in the season when it could boost kernel growth. In the video, Cowan illustrates this point by comparing the ear leaf, which tissue testing pegs at 7 ppm of boron, to the flag leaf which checks in at 28 ppm.
How can growers get that boron to move down the plant in a timely fashion during grain fill? Research indicates that adding a sugar alcohol to boron could significantly increase downward movement of the nutrient from the flag leaf to the ear leaf.
Cowan plans to run boron trials in 2025 comparing sidedress, foliar, and sidedress-plus-foliar treatments to have Ontario data to assess and ground truth the strategy. In the video, he also discusses how growers can use tissue testing to determine whether a corn crop is boron deficient. Watch the video below.
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