March 2006
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Looking for Reniform Nematodes in Limestone Co.

by Susie Sims

 
  Stan Usery, Jr., preparing soil samples to be tested for the presence of reniform nematodes in his lab in Limestone County.
Stan Usery, Jr. is on a mission. A mission to identify and eliminate reniform nematodes from cotton fields in Limestone County and the South.

Identifying the plant parasites is somewhat of a complicated process and eliminating them is nearly impossible. "The use of nematicides to control reniform nematodes is hit or miss," said Usery. "Nothing really is effective."

Usery is content, for now, to suppress this threat to cotton production in the South. "The way to suppress the nematodes is to rotate cotton plantings with corn," Usery said. "Rotation is really the only way to reduce population levels."

Usery has constructed a lab on his family’s farm to test for nematodes. Several seed companies have their customers send samples to his lab for testing. But much of Usery’s satisfaction comes from assisting local farmers in the Tennessee Valley.

"I know many of the producers in this area—I know their farms," said Usery. "I really enjoy helping these producers."

Turnaround time for testing results is usually less than two weeks. Results can be mailed, faxed or emailed.

Even though he may be a young farmer, Usery, 24, has seen more than his share of reniform nematodes. He received a B.S. degree from Auburn University in 2003 in Agronomy. He continued his studies with a master’s degree in Plant Pathology in 2005.

Prior to completing his undergraduate work, Usery began a comparative study on commercially available cotton varieties. In his thesis, Usery looked for which varieties exhibited a tolerance for reniform nematodes. He found no cotton variety with a tolerance to this nematode.

He also ran a three-year trial on the effects chicken litter might have on the unwelcome parasites. Usery’s greenhouse study showed that the litter had an antagonist effect on the nematodes. His field trials, though, did not show an effect.

Identify and Enumerate

 
Stan Usery, Jr., counting reniform nematodes using a microscope.  
Since total eradication of the reniform nematode is not possible at the present time, Usery is content to identify infestations and quantify the populations. He does this in his lab near Elkmont.

Most of his work is done in the fall. About 90 percent of his work is aimed at identifying reniform nematodes, but his lab can identify other nematodes, as well.

Once the soil samples are received, Usery begins the process of separating the soil and organic matter from the nematodes. He does this by passing the samples through progressively smaller sieves.

Once the nematodes are separated from the soil and organic matter, Usery uses the sugar sucrose centrifugation method to extract the nematodes. After he extracts them, the nematodes are then ready to be identified and counted.

Up to this point, the work is basic—just like what is done in any lab. In order to identify the nematodes, Usery must compare what is in the Petri dish to known images of the reniform nematode.

He said the name reniform is Latin for "kidney." Since the females look kidney-shaped while they are feeding, the parasite was given the name reniform nematode.

"I find other random nematodes in most soil samples," said Usery. "Usually it’s the kind that feeds on organic matter—not threatening to crops."

After he identifies the reniform nematodes, then he must count. Usery said severe infestations are represented by a population of 3000 to 4000 reniform nematodes in a 150cc soil sample.

According to Usery, populations in the Limestone County area are becoming more prevalent. One of the most common ways for the nematodes to be transported to a clean field is on equipment.

Once the nematodes are present in a field and cotton is planted, they have an automatic food base to feed from, noted Usery.

The Goal: Suppression

To suppress the growth of reniform nematodes in his own fields, Usery plants cotton only every third year. He rotates with corn and soybeans.

Usery said the nematodes are most active when the temperature is above 60 degrees. During this time, the females feed and reproduce 50 to 200 eggs every 20 to 30 days.

With an active reproduction cycle, a field with a small infestation at the beginning of the season can have a severe infestation by season’s end.

Once an infestation is detected in a cotton field, Usery advises rotating with corn to stunt the infestation.

Many times there is no indication that an infestation exists in a cotton planting. "There is no identifiable symptom other than bad yield loss," said Usery. "Many producers confuse the problem with fertilization problems. The only way to know for sure is to have the soil tested."

FFA Paved the Way

Like many young men who grew up farming, Usery would have been content to stay on the family farm for the rest of his life. However, he became interested in the study of agronomy and soils during his time in the Future Farmers of America (FFA) at Elkmont High School.

"My ag advisor, Randy Black-ledge, really got me interested in soils," Usery recalled. "If it hadn’t been for him, I probably wouldn’t have gone to college."

Even though he ended up back on the family farm, Usery is glad he decided to complete his formal education. "I will always have that education, whether I use it here or elsewhere," he said.

Usery recalled that while at Auburn University, he was surrounded by young people with similar interests to him, just like during his FFA years. "FFA is practical education," said Usery. "It teaches leadership, as well."

Celina Gaines, manager of Limestone Farmers Co-op, stated that she had met Stan, Jr. while attending Auburn and is proud to see innovative people like him keeping up with advancements and keeping agriculture alive.

Usery farms with his father, Stan Usery, Sr. They have nine broiler houses and 400 no-till acres of cotton, corn and soybeans. He said the family began row-cropping again to make use of the chicken litter from their operation.

Usery, Sr. serves on the board of directors for the Limestone Farmers Co-op in Athens.

Usery’s wife of two years, Kayla, manages the CVS store in Madison.

Usery’s lab can be reached through its website, useryconsulting.com.

Susie Sims is a freelance writer from Haleyville.