In Louisiana, high micronaire, not low, is the primary problem. This is due to overdevelopment of fiber. A good fertility program — especially as it relates to potassium — can help offset the tendency to of cotton fiber overdevelop. Potassium is key in movement of water in the plant.
Because high micronaire has been a major problem for Louisiana cotton growers the past two seasons, LSU AgCenter specialists say now is the time to start planning to avoid such problems this growing season.
Micronaire is a measurement of the lint surface area or cotton, and John Barnett and Don Boquet of the LSU AgCenter said measurements above 4.9 or below 3.5 will result in a discount charged on the price paid for the cotton.
Barnett, LSU AgCenter cotton specialist, and Boquet, LSU AgCenter agronomy professor, said there are management techniques growers can use to give them an edge on this important fiber quality characteristic.
“Variety selection is key to micronaire,” Barnett said. “Genetics are the primary means of insuring a good micronaire from your crop; however, micronaire has not been a high priority in variety development during the past several years.”
Over the past three years in LSU AgCenter evaluations, there has not been much high or low micronaire cotton — based on the average results of statewide tests at all research locations. “Most of the problems we see occur under farm conditions,” Barnett said.
But Boquet said he has noted a trend toward higher micronaire at research stations located in the northeastern section of the state over the past few years.
“How you manage your crop can have a definite effect on micronaire, regardless of where you farm or what variety you plant,” Boquet said. “There are four major production areas where growers can impact micronaire — stand, irrigation, fertility and defoliation.”
Most micronaire problems occur in seasons when the conditions are hot and dry, especially late in the season, which is July through harvest, Boquet said. “Anytime a grower can use irrigation to offset these conditions helps keep the crop out of the micronaire discount range. Proper irrigation can allow the plant to set a top crop.”
Timing is the key to irrigation, Boquet said. The biggest problems come from starting irrigation systems too late or waiting too long between one application of water and another.
“If you are going to irrigate, it is critical that you be on some kind of management schedule,” he said. “We recommend the Arkansas irrigation scheduler for our region, but you can also place tensiometers in the field or rely on visual inspections.”
While visual inspections are used, Boquet warned they can be misleading and can often mean a late start on irrigation.
In Louisiana, high micronaire, not low, is the primary problem, Barnett said. This is due to overdevelopment of fiber. “A good fertility program can help offset this tendency,” he said. “This is important, especially in terms of potassium levels. Potassium is key in movement of water in the plant. That makes adequate potassium levels in the soil a key to avoiding micronaire problems.”
A uniform stand also can reduce the possibility of high micronaire problems, he said.
What happens at the end of the season can be as important to micronaire as what happens during the season. Early defoliation actually can lead to low micronaire cotton, because too much immature fiber is being harvested, the LSU AgCenter faculty members say. The opposite problem can occur if a grower defoliates early and leaves a lot of the top crop in the field.
If 50 percent to 70 percent of the lint is picked off parts of the plant that are higher micronaire, then growers will not get the blending effect of the entire plant in the samples that go to the classing office, Barnett said. That can mean samples come back as high micronaire.
Barnett and Boquet encourage growers to start planning their strategies now and to call their local LSU AgCenter offices for assistance.