The primary purpose of a PGR in cotton, says Monks, is to manage excessive growth and set more bolls.

It’s difficult to predict whether a plant growth regulator increases yield, decreases yield, or if it’s yield neutral, he says.

“We can look at data going back many years, and according to the season and according to the variety, a PGR may help you harvest your crop. It may not increase your yield but you may be able to harvest it better because the picker did not have to deal with as much plant material. Maybe it allowed you to get more insecticide down into the canopy. As a result of using a PGR, you’ve got more control over how that plant looks and how it goes through the picker, and you can count that as increasing the yield. It’s a crapshoot as far as what it does for yield on a plant to plant basis.”

It’s for certain that cotton treated with a Pix-type product is darker green than a non-treated plant, he says. In addition, the leaves are smaller and a little bit thicker.

“The chlorophyll is concentrated a little bit more, so you’ll end up with a darker green plant than you would otherwise. Also, it’s more compact. We know that if we put out PGR in the middle of a drought, we’ve done harm to cotton. There’s no doubt about that. There are certain things we have to avoid.”

In addition, late applications don’t help much, says Monks. “The idea is to load the plant as you go, and there are different strategies for that. We used to apply 8 ounces at early bloom and then another 8 ounces. But then we went with 10 to 12 ounces at early bloom and maybe another 10 to 12 ounces 10 to 14 days later. Some varieties need more than that.”

You have to keep a certain level of concentration of PGR in the plant to keep it under control and to prevent it from growing excessively, he says.