Clemson student studies extra-long staple cotton for production in South Carolina

DARLINGTON – All cotton is not created equal and a Clemson University student is looking to bring back a species that once dominated South Carolina cotton fields.

Sarah Holladay, a master’s student from Florence who is studying plant and environmental sciences with a focus in agronomy, is working with Clemson Extension Service cotton specialist Mike Jones and USDA-Agricultural Research Service cotton geneticist Todd Campbell at the Clemson Pee Dee Research and Education Center to determine if pima cotton can be productive in South Carolina after an almost 100-year absence. Holladay believes pima could benefit the state’s cotton farmers.

“Pima is worth more than double the price of upland cotton due to its superior fiber quality,” Holladay said. “Pima fibers are longer, stronger, finer and more uniform than upland cotton, making pima cotton easier to process and spin into thread. The textile industry and export markets are constantly requiring higher quality cotton with pima-like fiber properties.

Pima cotton flourished in the Lowcountry of South Carolina before boll weevils wiped it out in the 1920s and the state’s cotton farmers turned to growing upland cotton. Most pima cotton today is grown in Arizona, California, New Mexico and Texas.

Holladay is studying lint yield, gin turnout, fiber length and fiber strength. Fiber length affects yarn strength, yarn evenness and spinning process efficiency. Pima fibers measure between 1.25 to almost 2 inches long, while upland cotton fibers range from about 0.875 to 1.312 inches long. Fibers shorter than 0.5 inches long are not considered suitable for spinning and have no commercial value for the textile industry.

Information from Cotton, Inc., shows fiber length is largely influenced by variety, but cotton plants’ exposure to extreme temperatures, water stress, or nutrient deficiencies may also result in shorter fibers.

“In our study, the Bleak Hall pima accession was found to have the longest fibers,” Holladay said. “It was grown in South Carolina prior to the 1930s. It had an average fiber length of 1.65 inches when ginned on the roller gin, and 1.49 inches when ginned on the saw gin.”

Bleak Hall is an accession that originated in Charleston. An accession is a group of related plant materials from a single species collected at the same time from a specific location. Gins are used to separate cotton fibers from their seeds. Saw gins normally are used to gin short-staple cotton and roller gins are used to gin long-staple cotton. Most South Carolina gins are saw gins. Holladay said determining if the same gins can be used to process long-staple cotton is one objective of the study.

“Of the 50 varieties in the study, just six responded to the ginning method,” she said. “Five varieties performed better on the roller gin and one performed better on the saw gin. More data is needed to determine which gin performs the best.”

In addition to using the same gins, Holladay said farmers also can use the same machinery to cultivate and harvest pima cotton as they do for upland cotton. Although some pima varieties mature later and often require an additional 3-4 weeks to ensure maximum yield potential, the growing seasons for pima and upland cotton are similar. Planting for both generally occurs around late April. Harvest is done around October.

Until she has some definite answers on pima cotton, Holladay said South Carolina farmers probably will see more advantages by growing upland cotton.

“Upland has had more genetic improvements than pima and generally yields more than pima in South Carolina,” she said.

Depending on quality, transportation and market demand, South Carolina farmers might profit from growing pima cotton, Nathan Smith, Clemson Cooperative Extension Service agribusiness economist, said.

“The 10-year and 5-year average price for American pima cotton was $1.42 per pound and $1.37 per pound respectively,” said Smith who is located at the Clemson Sandhill Research and Education Center. “The 10-year average price for U.S. upland cotton was 72 cents and 66 cents per pound for the last five years. The difference over the last 10 and five years has averaged 70.9 cents and 71 cents per pound. Basically, there has been a 71-cent difference between the U.S. pima and U.S. upland cotton price with pima receiving the higher price. The net revenue would depend on the costs and yield to grow pima cotton in South Carolina versus upland cotton.”

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