For many cotton growers across the Upper Southeast 2012 weather has been dramatically different during the growing season than the past two years, and North Carolina State University Cotton Specialist Keith Emdisten says growers need to have plenty of patience when deciding when to defoliate their cotton this year.

In 2010 and 2011, drought plagued cotton production at various times during the growing season and many growers essentially lost the middle bolls, or middle crop of their cotton.

In 2010, some growers defoliated for the top crop, because they didn’t have good middle and lower plant boll set, and that was the right choice under those weather conditions, Edmisten says.

Last year cotton got beat up pretty good by a hurricane and tropical storm and defoliating to save the top crop was not such a clear cut choice. Some people put on defoliants to try and get the cotton to stand up after the storms, and it was just a difficult choice of when to defoliate last year, he adds.

This year most cotton growers have had ample moisture, so there is no missing zone of fruit — there is a bottom, middle and top crop on most cotton in the region. “We have a more compact cotton crop, and that affects the timing of defoliation, Edmisten says.

“If you use the first position cracked boll method to determine when to defoliate in a compact crop, there may be some surprises.

“I had a cotton grower tell me this morning (Sept. 12) that he defoliated his cotton, using the same system he used the past few years, and his cotton was only 30 percent open,” he adds.

Must be on time

In a year like this it is critical to be on-time with defoliation. No grower wants to sacrifice yield by defoliating too early, but on the other hand in a year with lots of rank cotton, you can’t afford to wait too long to defoliate.

There is plenty of rank cotton in North Carolina this year, which has generated lots of questions about when to defoliate, Edmisten says. The first inclination is to up the rate of defoliant to get better defoliation of rank cotton.

“If you do up defoliant rates, all you will usually do, especially with herbicide defoliants, is stick a bunch a leaves in the top of the plant and get poor defoliation in the bottom part of the plant.

“With rank cotton, I tell growers to use the same defoliation rate and practice, keeping the sprayer pressure high enough to get good coverage, that they would use on healthy, not rank cotton.

“Then, re-evaluate in a week or so, and determine whether you need to come back and defoliate the cotton again,” Edmisten says.

This year cotton growers in North Carolina used a lot of nitrogen on their crop, compared to the past two years, when they had plenty of residual nitrogen in the ground, because of the dry weather.

The residual nitrogen caused lots of problems with re-growth and growers tended to up the rate of materials like Dropp to take care of re-growth.

“In most of the cotton in North Carolina, it appears nitrogen is playing out as we move toward harvest season, so there may not be as much need to add extra materials to manage re-growth,” Edmisten says.

Standing in a beautiful field of Phytogen 499 cotton on Sept. 12, Halifax, N.C., grower Lee Dickens was living out Edmisten’s advice to be patient.

“I’m ready to defoliate this cotton field, but it’s just not ready. The past couple of years by this time, this field of cotton was nearly ready to be defoliated and some of my early maturing varieties were ready,”  Dickens said.

The North Carolina grower said he has been blessed with good rainfall throughout the growing season and it’s that anticipation of a good crop that makes him want to get the cotton ready to pick.

Will make sure it’s ready

Like most veteran cotton growers, Dickens says he going to fight the temptation and wait until he’s sure his cotton is ready for defoliation.

Proper timing of defoliation is key to maintaining fiber quality at the end of the season. Poor defoliation timing can be economically costly. Defoliating too early lowers lint yield and fiber quality, especially micronaire.

Defoliating too late increases the likelihood of boll rot and lint damaged or lost due to weathering. Defoliating too late will also lead to discounts from high micronaire values with certain varieties as well as increase the possibility that defoliant activity may be inhibited by lower temperatures.

In some parts of eastern North Carolina and southeastern Virginia, too much rainfall has created major problems and potentially significant yield loss.

Gary Respess, who grows cotton near Pantego, N.C., says his crop has taken a big hit from boll rot this year. “All through the growing season the crop looked great, but as the crop neared maturity we stayed wet for several weeks and we’re really fighting the boll rot problem,” he says.

Yield loss from boll rot and hard-lock in the 20-30 percent range is common in North Carolina’s Blacklands in the eastern part of the state. Hard-locked cotton is going to make defoliation timing an even bigger challenge.

“Hardlock” of cotton is a generic term used to define a condition where even though the lint appears to form normally, it does not “fluff” and thus cannot be picked with a spindle picker.

Hardlocked cotton bolls are a significant problem for growers, but the exact cause isn’t so clear. Stinkbug damage has been documented as one cause, but likely a bigger cause is weather-related damage from a variety of pathogens that cause boll rot in cotton.

Regardless of the cause, the bottom line for cotton growers in the Upper Southeast this year is cotton defoliation is likely to come later than in the past few years.

Patience is a virtue in most things, and it  appears cotton picking will be among those things this year.

rroberson@farmpress.com