As of Aug. 13, the Mississippi cotton crop was close to the last effective bloom date.

“In Tunica County, based on 30 or 40 years of weather data, the last effective bloom date is about Aug. 14,” said Darrin Dodds, Mississippi State University Extension cotton specialist, at the Late-Season Crops Field Day at the Delta Research and Extension Center in Stoneville. “As you move south (towards Stoneville), it’s Aug. 20 to Aug. 22. Farther south, it may be Aug. 25, depending on the weather.

“So, say it’s Aug. 22, that’s basically telling you that there’s a good chance that a bloom on the plant will make it into the picker basket. As the season progresses a week, or two, past that the chances get progressively lower to get that bloom harvested.”

The reason that matters, said Dodds, is “it can help you tailor some of your management decisions. We have a crop that’s a little late because of planting date. We tended to plant around three or four windows because of the rain, wind and weather.” 

To illustrate several things, including the importance of fruit retention, Dodds held up two plants freshly pulled from test plots. “The only difference between these two plants is the way they were managed for plant bugs. There’s about an eight-inch high difference. (The untreated plant) has less fruit compared to the (treated plant), which is running 80-plus percent fruit retention versus (the untreated) at 20 to 30 percent. That shows you what a good fruit load will do with respect to height management in cotton.”

Recently, Dodds has fielded many questions about late-season cotton. “Folks are asking, ‘What do I need to do with plant growth regulators to try and stop this crop?’ I’ve been telling them that at this time of year you don’t need any more vertical growth on that plant. All that will do is make a switch at the top of the cotton plant. … If there’s one thing people hate to see in a cotton field is a switch at the top of a plant. It makes people mad to even see it.

“However, my phone has been ringing about what to do with this crop. When you get into some of the more aggressive type varieties -- Phytogen 499 or DPL1321 to some degree, even a Stoneville 4946 -- and you take the fruit retention down, it makes it that much harder to control from a vertical standpoint.”