A large cotton field at sunset with a dust cloud rising from harvesting equipment.

Managing for Fiber Quality Optimization After Planting

Variety selection and placement are two important first steps to maximizing fiber quality on any given field of cotton. After planting, however, there are agronomic practices that can help maintain a cotton variety’s fiber quality potential.

“Fiber quality can be influenced to various degrees by the agronomic circumstances in almost any field,” said Jay Mahaffey, a Bayer Science Fellow and research manager at the Scott Learning Center in Scott, Mississippi.

Micronaire Management

While length and strength are generally more determined by the variety genetics, stressful conditions can, and often do, affect these fiber measurements. Droughty, harsh growing conditions can negatively influence fiber length and strength. Micronaire, however, is the measure of fiber quality that can typically be most influenced by crop management practices, Mahaffey said.

Micronaire is a measure of fiber fineness and varies across the plant by fruiting position and boll age. Older bolls are typically higher micronaire (coarser, more developed fiber) and younger, less well-developed bolls are often of lower micronaire (finer, less-developed fiber). The primary goal of optimizing micronaire in a cotton crop is to have a blend of the boll ages and micronaire types, which often produces fiber of the preferred quality – that is, not too coarse and not too fine and preferred by textile mills. Defoliation timing is an important management practice for maintaining good fiber characteristics, such as micronaire.

Generally, cotton crops that are allowed to naturally open will tend to be of higher micronaire values, particularly in varieties prone to higher measurements. Therefore, defoliation timing often has a significant impact on micronaire measurements across a field. Growers should consider defoliation in the range of 50% to 60% open boll count to try and avoid problems with high micronaire, said Mahaffey.

“Understanding the season-long fruit accumulation profile in a field can aid in defoliation decisions,” Mahaffey said. “Crops with poor fruiting in the bottom will typically show reductions in micronaire, crops with reduced fruit retention in the top third of the plant will drift to higher micronaire values, particularly when allowed to naturally open. This balance can and should be used in concert with varietal background when establishing defoliation timing for every field, farm and situation.”

Managing Growth

Growth management and defoliation timing are two areas Paul Freund focuses on to try and achieve optimal fiber quality on his farm in Needville, Texas. Staying on top of plant growth regulator applications helps prevent his cotton crop from growing too tall during seasons of timely rainfall in the Upper Gulf Coast region. Managing plant growth helps set the crop for a good harvest, he said. Then, it is about defoliation timing so open cotton doesn’t get rained on too much.

“Counting open bolls, monitoring weather patterns and pulling the trigger on defoliation applications at the right time is important,” he said. “Genetics play a big role in fiber quality, but plant growth management and defoliation timing are two areas that we, as farmers, can focus on to try and manage for optimal quality.”

Growing conditions are obviously beyond the growers’ control.

“I always say control what we can control when growing a cotton crop,” said Deltapine® technical agronomist Scott Stanislav in South Texas. “Although we can’t choose when we are going to be faced with a year of higher-than-normal temperatures and drought, we can control our inputs.”

There are four basic management practices to focus on, according to Stanislav:

Planting a high-quality variety

Fertilizing properly (especially potassium)

Managing the crop properly with plant growth regulators

Harvesting in a timely manner

“These factors can help mitigate risk for fiber quality losses in a season of high heat and drought stress,” said Stanislav.

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