Precipitation events during October 1 – 12 period brought to the Kansas wheat growing region anywhere from ~0.46 inch precipitation in the far northwest to as much as 9.7 - 12.6 inches in portions of south central and northeast Kansas (Figure 1). This early-October precipitation resulted in fields with a saturated profile for most of the state, but also water logged conditions that stopped fieldwork. In addition to the excessive moisture, air temperatures and soil temperatures decreased during the same period (Figure 2). The change in soil temperatures was also very rapid and some locations experienced a 20 degree F drop in soil temperatures in the last week alone (Figure 3). Decreased soil temperatures during this crucial period can delay wheat emergence and expose seed to a prolonged time of sub-optimal conditions.
Figure 1. Cumulative precipitation during October 1 – 12, 2018. Map by K-State Weather Data Library.
Figure 2. Current (left panel) and weekly average (right panel) soil temperatures at the 2-inch depth for the State of Kansas. Maps by Kansas Mesonet (http://mesonet.ksu.edu/agriculture/soiltemp).
Figure 3. Soil temperatures at Cheyenne at both the 2-inch and 4-inch depth (mesonet.k-state.edu/agriculture/soiltemp/).
These suboptimal conditions to field work caused by the excessive rains will probably result in a delay in sowing progress in Kansas, although this delay has not yet been noted in the current USDA planting progress report as of October 9 (Figure 2). If producers are forced to delay sowing past their optimal window, wheat fall growth might be compromised due to less time to tiller, which might require some management adjustments to maximize crop productivity.
Figure 4. Wheat sowing progress in Kansas during 2018 (dashed line) as compared to the 1994 – 2016 average (solid line) and range (purple area). Wheat area sown in the current year was on pair with the long-term average as of the latest USDA report (Oct. 9), but this is likely to change in the next report due to the excessive rainfall conditions around the state. Graph based on USDA-NASS crop report of progress as of October 9, 2018.
Management adjustments to consider when sowing is delayed past optimum sowing window include:
On a final note, a couple of positive things about the sowing progress delay are that: (i) the majority of the state have a good profile moisture, which will not only ensure good stand establishment but also possibly contribute to wheat grain yield potential; and (ii) late-planted fields are less likely to be infected with wheat streak mosaic, as the wheat curl mite populations would be more active in warmer temperatures generally observed under early planting. Thus, we are probably decreasing the risk of another wheat streak mosaic outbreak due to the delayed planting.
Romulo Lollato, Extension wheat and forage specialist
Erick DeWolf, Extension wheat pathologist
Mary Knapp, Weather Data Library
Christopher Redmond, Kansas Mesonet