Wheat School: Proper timing of PGRs for maximum effectiveness

If you are planning on applying a plant growth regulator to your wheat crop, you are most likely aware that proper timing is critical to success.

But how do we know when that timing is right to get the most out of your crop?

In this episode of RealAgriculture’s Wheat School, Jeremy Boychyn, agronomy research extension specialist for Alberta Barley and Wheat, talks to field editor Kara Oosterhuis about applying the PGR chlormequat chloride (trade name Manipulator) on wheat.

“If any producers used PGRs in the past, what would’ve been used was Ethrel, where there was a large potential to see yield reduction. So the timing of PGRs has been instilled to be quite sensitive. But with Manipulator, there’s a bit wider of a window, where you are either going from growth stage 12 up to 39,” explains Boychyn. “However, the ideal timing for Manipulator for efficacy is in that BBCH stage of 31-32.”

While many producers are more aware of the 5-leaf stage when it comes to timing, Boychyn cautions that although this can be used as an indicator, it isn’t the most accurate way to tell. (Story continues below video)

“The only way to really tell whether you are in that stage is to go into the field, dig up a few plants, and split those plants down the centre. You are looking for internode length. So BBCH 31-32 is a distinctive stage where there is a certain distance between each internode,” he notes. “So stage 31 is when you split that wheat stem down the centre, and that first internode is just over 1 centimetre over that tiller node. And BBCH 32 is when that second internode comes up, and it is pushing up that first internode. And the distance between that first internode and the second internode is about 2 centimetres. If you’re in that timing, it’s ideal timing for Manipulator.”

When it comes to the use of Manipulator, there are some other factors to consider when it comes to the final product of your crop.

“Because you are using a plant hormone, it can also affect other parts of the plant as well, including protein, yield, and late tillering. What we’ve seen with some studies is that we get increased late tillering, not with every variety, but with some varieties, so it’s something to keep an eye out for,” Boychyn explains. “We also see some changes when it comes to protein, although nothing consistent, so you can’t really depend on it to increase or decrease protein too much.”

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