Measuring Variety Responsiveness to PGRs

Measuring Variety Responsiveness to PGRs

New cotton varieties have taken large chunks of 2017 acreage, and limited information is available on how some of them will respond to PGR applications. Tyson Raper, University of Tennessee Extension cotton and small grains specialist, suggests that growers be sure to base PGR timing and rate off of plant measurements.

In a recent blog, “Managing Cotton Plant Growth in 2017,” Raper includes a table representing a “best guess” as to how some of those new varieties will respond. Classification is based on determinacy, growth habit and direct response to the regulator.


“The best approach to managing growth in a new variety is to use multiple, low-rate applications based on plant growth measurements,” says Raper. “Several different measurements can be used – and multiple should be considered – but the most emphasis should be placed on current growth by measuring the internode length between the fourth and fifth nodes.”

The online report also includes information on PGR application strategies, including input on treating acres where target spot occurred in 2016.