Blog: The Wheat Sheaf
Regrowth: Managing Late Tillers at Harvest for Grade or Feed
A major issue currently noticeable in some parts of the province is “regrowth,” which is induced by earlier periods of drought stress followed by periods of moisture. It is most commonly found in fields that have received heavier rains in July after a dry June. Such moisture after a dry period induces new tillers and thus new green heads that are usually far behind the maturity levels of the main stem heads.
When regrowth is involved, a decision has to be made as to whether there is time to wait for such green heads to mature naturally before swathing and or combining for grain production, or if they are too late, reduce the number of green seeds that end up in the hopper. Another option for growers with cattle is to graze, bale or silage the crop for animal feed.
If the new regrowth is just too dominant and/or too late in coming to make mature seed prior to a killing frost then these latter options would make the most sense. However, sometimes adjusting combine reel height at harvest to cut above regrowth can miss much of any late season regrowth, but it does leave taller straw to deal with later.
The decision should be on knowledge of the variety’s maturity potential and on knowledge of your normal killing frost date.
My experience in variety experiments is that earlier maturing spring wheat varieties tend to be more resistant to re-growth simply as a function of a more compressed growing period, but also tend to allow any regrowth that does occur to mature in time, again, as a reflection of a shorter window needed for reaching maturity.
A few regrowth heads are not normally an issue if at least colour change in the seed itself can occur prior to harvest. The maximum grass green seeds allowed for CWRS number 1 is .75% and for CWRS number 2 is 2% so having too many in the sample could cause downgrading and lower returns. This is the same for all other spring wheat classes of wheat except CWES, CPSR and CPSW where tolerances are higher at 2% and 10% for Number 1 and Number 2 respectively. However, if a lot of regrowth has occurred or it is likely going to be still grass-green seed by harvest and cannot be avoided by adjusting reel height when straight-cut, one needs to consider swathing the crop and early enough to help this late seed to dry down. It may be possible to adjust the fan speed or screen opening to blow a lot of the lightweight immature seeds out the back of the combine but any that end up in the hopper may cause storage issues.
Furthermore, note that it is off-label and thus not legal to use glyphosate to help dry down re-growth if such is not past physiological maturity – which is most often the case. There is definitely less risk involved for wheat crops destined for feed wheat where there is no limit on green seed.
For producers with wheat fields not yet past this critical 30% seed moisture stage, one should be aware of this maturity issue.