Time To Be Harvest Ready
Even with low cotton prices, growers must spend much time and money to control weeds, bugs and disease. But to finish the crop, timely defoliation is essential to maximize yield and quality. And early picker and stripper maintenance is vital to prevent downtime in mid-harvest when storms are approaching.
Extension Specialists Ken Legé, Texas A&M AgriLife; Brian Pieralisi, Mississippi State University; and Zachary Treadway, University of Arkansas Division of Agriculture, stress that plant growth regulators are key to fruit retention in both types of production.
“Harvest preparation starts midseason,” explains Pieralisi. “Using PGRs appropriately per variety will more effectively manage the architecture of the plant, allowing for a more efficient picker harvest. They can help plants average 4-5 feet tall, and a 2–3-inch fruiting node spacing that typically produce the best yields and quality.”
Legé notes that West Texas and Panhandle farmers welcomed above-normal rain in many areas. However, hotter conditions in August threatened the crop. “Timely PGR applications hopefully helped manage those conditions,” he says. “If we can maintain boll retention through hot periods and we return to wetter, milder conditions, that good fruit load may carry the crop to a ‘normal’ cutout that could make harvest prep a bit easier.”
Picker System Preparation
Harvest equipment is as high tech as ever, but breakdowns can happen. And with harvest windows often narrow, stoppages can cause misery at the turnrow. “It’s crucial to assure we’ve gone through the picker nose to tail,” Treadway says. “Annual maintenance on spindles, doffers, and other components is crucial.
“If we handle all that early, there’s less chance we will fix problems during harvest. That’s why it’s important to have every piece of equipment ready to go when the harvest window is open.”
Picker maintenance can be a season-long task. Defoliation, however, must be timed according to plant growth. Pieralisi describes defoliation “as much of an art as a science” and is more effective when conditions are warmer and drier.
A wide range of harvest aid defoliants, boll openers, and desiccants include herbicidal types such as Reviton, Ginstar, Folex, Aim, ETX, Display, Sharpen, Gramoxone and Paraquat. Hormonal type defoliants include Finish 6 Pro, Ginstar, Cutout, and various other formulations of ethephon and thidiazuron. The hormonal defoliants induce production of ethylene, a stress hormone.
Pieralisi says growers should look for 60% open bolls or mature bolls 4-5 nodes from the top. “With a sharp knife, cut bolls in cross section and look for dark seed coat on the outer ring of seeds,” he says.
There are two general methods of determining when cotton is at cutout: Nodes Above Cracked Boll (NACB) and the traditional Nodes Above White Flower (NAWF) and 850 DD60s method.
“The NACB technique involves frequent plant mapping to determine the node of the first position cracked boll and the number of fruiting branches above the cracked boll,” Pieralisi says.
“Research indicates that at least four nodes above the highest first position cracked boll will be mature enough not to be adversely affected by the application of a harvest aid. The field can be defoliated when the first position cracked boll is within four nodes of the last boll you want to harvest.”
In trying to initiate defoliation on time, use the weather to your advantage. “With later cotton, be ready to be flexible and try to get the most you can out of the crop,” Pieralisi says. “But depending on the weather this fall, don’t wait forever on a couple of top bolls if the weather is trending for the worst.”
Treadway says diligent crop monitoring is the only way to determine when to start defoliation. “The NAWF5 plus 850 DD60 and NACB methods both work well,” he says. “But both techniques also have their drawbacks, and that’s why the sharp knife technique is so important. The NAWF5 plus 850 DD60 method can sometimes trigger defoliation too early which can lead to yield loss. If using NAWF, it’s wise to pair it with the percent-open method.
“The NACB method can be affected by plant population and can trigger defoliation slightly early as well. There is merit to both techniques. Producers should make their own choice but also consider using more than one method.”
Stripper System Preparation
In Texas, some growers plant picker varieties in the more southern production. However, West Texas or Oklahoma cotton is mainly stripper-harvested. “We could see an uptick (in picker harvest) due to recent interest in ELS (extra-long staple or 1 3/8 inch or longer) acres,” Legé says. “Harvest aid strategies are much less complicated for picker harvest because a desiccant is not needed. But oftentimes, two applications are necessary on higher-yielding fields.”
Legé says stripper harvest requires a desiccated plant for the stripper harvester to function properly and to maintain fiber quality. “On higher yielding fields, the same two-shot defoliation/ boll opening approach is followed, then applying a desiccant, typically paraquat 5-7 seven days before harvest or at around 2-3 NACB.”
He says limited-irrigated and better-yielding dryland fields more often follow a one-shot defoliant/boll opener, then desiccant application. Lower-yielding dryland fields may wait on the first freeze for defoliation to cut costs.
Legé advises growers not to judge the number of bolls open from a distance. “More often than not, I see growers applying harvest aids too late. Oftentimes, growers are busy and may estimate the percent open at 75 mph from the highway,” he says.
“Fields that look 30-50% open can actually be 60-80% open. Defoliants could have been applied 7-10 days earlier. That difference could pay dividends if a fall storm moves in, deteriorating quality and reducing yield. The highest quality of each boll is attained the day it opens. Once open, quality can only deteriorate.”
With the variable West Texas weather, Legé leans on the NACB method over the percent-open method and less so the NAWF/DD60 method to judge when to defoliate.
“Environmental conditions between cutout (3-4 NAWF) and defoliation are unpredictable and less reliable in our geography,” he says. “The only scenario in which I deviate from using NACB for timing is if the crop has a significant fruiting gap. In that scenario, I recommend using NACB combined with the percent-open to get a better perspective.”
Preventive maintenance on strippers is highly recommended. “For example, changing all the bearings before harvest season may pay off by being better poised to get the crop out before a storm,” Legé says. “Nothing is more frustrating than having to change bearings on the second field you harvest.”
With higher-than-normal rain and the chance for a better crop, Legé encourages growers not to skimp on harvest aids.
“Typically, harvest aids are good investments that deliver positive ROI,” he says, “but don’t chase that last boll at the expense of losing better yielding bolls.
“Growers and consultants must estimate the size of that boll and the quality potential,” he adds. “Sometimes waiting for a small boll with short length, low strength, and low mic simply isn’t worth losing a larger boll with better quality in the lower canopy that may deteriorate due to weathering. These are field-by-field decisions that are sometimes difficult to make.”
Treadway says the Mid-South cotton specialists release an annual defoliation guide offering more detailed information on getting the crop ready for harvest. “We can’t control Mother Nature, but we can control our ability to be ready,” he says.
Other state Extension services also provide regional harvest aid guides.
GET THE NEWSLETTER TODAY!
