Late-developing tillers and green heads in wheat
Most of Kansas received significant rainfall in May after being dry for most of the winter and spring. One result of this has been a flush of growth in late-developing tillers. Where this has occurred, there is essentially a second canopy of green heads along with the main canopy of ripe heads.
Heads that form this late in the season in a crop otherwise nearing maturity usually add very little to the overall yield of a field. If these late, green heads are not close to being ready to harvest when the majority of the crop has dried down, then it’s best to start harvesting the field anyway. Waiting for the green heads to mature would risk grain losses due to shattering or hail damage. With varieties that tend to shatter easily, producers should start harvesting as soon as the field reaches 15% moisture.
Most of the immature grain and green plant parts will go out the back of the combine when the crop is harvested, but enough green material may go into the bin to increase the dockage and overall moisture level of the load of wheat to some extent. Combine settings can help minimize problem, but not eliminate it. If a large amount of immature grain goes out the back of the combine, this could result in a greater-than-normal amount of volunteer on those fields this summer. In that cases, those fields will have to be watched especially closely and the volunteer controlled.
The situation is a little different where the main canopy is several weeks away from being mature. In that situation, the green tillers could develop quickly enough to add a significant amount to the yield potential. Still, unless the green tillers make up more than half the heads in the fields, it’s probably best to just start harvesting when the majority of heads are ready to go if there is a maturity difference of several days or more between the ripest and least developed heads. Waiting for the green heads to ripen might lead to shattering of the more mature heads.
In northwest Kansas, for example, there is enough time in most cases to wait and see how the new green shoots develop. If the weather is favorable and the new tillers have time to mature, producers in northwest Kansas may want to wait until they have ripened before harvesting. In north central Kansas, where the existing yield potential in some fields is higher, the new tillers won’t add that much to the final yield in most cases.
Producers who are harvesting wheat with some green heads present should take special care to measure the moisture content of the grain if they plan to store it on farm, and use air aggressively to dry the grain if the moisture content is high.
Jim Shroyer, Crop Production Specialist Emeritus