Delayed Corn Planting and the U2U Tool

Normally, we refer to the first half of May as a safe planting window to explore a longer growing season. Sure, weather permitting. Over May, several regions in Ohio have received enough precipitation that has not made that planting target possible, hence delayed planting. Delayed planting makes the growing season shorter in calendar days and available growing degree days (GDDs).

On May 23, the USDA National Agricultural Statistics Service reported that 52% of corn was planted in Ohio, seven points below the five-year average. Already on the last day of May (May 31), it is expected that most corn in Ohio has been planted. If still planting corn, adjusting to shorter maturities can give an advantage or mitigate the risk of fall frost or killing freeze before the crop reaches maturity.

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Emerged corn at the V1 stage in Wayne County, Ohio on May 31.

Useful to Usable (U2U) is a tool that can help as part of this decision. U2U can make county-level estimations across the US Midwest, including Ohio. Estimates are based on current and historical GDDs, planting dates, relative hybrid maturities, GDDs to black layer, and freeze temperature values. You can use U2U to test different scenarios and inform your decisions, specific to your location and conditions.

For using the U2U tool, five steps are needed:

Step 1. Access the U2U here: https://mygeohub.org/groups/u2u/purdue_gdd.

Step 2. Select your location, zoom in-or-out as needed in map. Search by Zip/City/County can be used.

Step 3. Select the start date for GDD. As a proxy, the planting date can be used here.

Step 4. Select your corn hybrid maturity. For example, 108 days, 114 days.

Step 5. Observe the projections. Ensure all boxes are checked on the upper left-hand side of the screen.

The U2U figure will include the 2022 GDD line, average GDD from 1981 to 2010, last freeze dates in the Spring, first freeze dates in the Fall, expected silking dates, and black layer. You can see the outcomes using a predetermined location, date, and hybrid maturity. You can repeat the exercise as many times as needed to evaluate other potential scenarios.

For example, specific to Hancock County, Ohio, May 31 GDD start, a 114-day hybrid was conducted (Figure 1). From this result, the earliest black layer date is October 25 (the actual and latest black layer date is projected for later). The risk of the crop being affected by freeze events are high.  

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Figure 1. U2U projections for Hancock County Ohio, GDD start date of May 31 and 114-day hybrid.

A second example is for the same location (Hancock County Ohio), same GDD start (May 31), but adjusting to a shorter relative maturity of 106-day (Figure 2). From this result, the earliest black layer date is October 2 (the actual and latest black layer date is projected for later). The risk of the crop being affected by freeze events are lower than in the previous scenario, but the chances are still high.

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Figure 2. U2U projections for Hancock County Ohio, GDD start date of May 31 and 106-day hybrid.

Note: U2U assumes the same GDDs to reach the black layer for the same hybrid, regardless of when it is planted. There has been some information that pointed to hybrids maturing with fewer GDDs if planted later. More information on this can be found here (from Corny News Network).

Closing: planting hybrids of varying maturity can be effective strategy for managing risk. Some shorter maturity hybrids can yield similar to longer maturities, although longer maturities should have a higher potential. Shorter maturities can benefit harvest ease and grain drydown.

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