Researchers often tell cotton producers not to base decisions solely on one year of a study or on how a previous season turned out. The advice was never more clear than after the 2003 growing season, according to Tennessee Extension cotton specialist Chism Craig.
Last spring, Craig began a study comparing yield from two cotton varieties planted April 28, May 20 and June 2. Craig discussed the study, sponsored by Cotton Incorporated, during the Milan (Tenn.) No-Till Field Day.
Similar studies were begun in 2001 in the Missouri Bootheel by Extension cotton specialist Bobby Phipps. Phipps started planting his 2004 tests in late April and planted every week until June 1.
The studies address observations that later-planted cotton has at times yielded higher than earlier-planted cotton, due in part to new technologies such as Bt cotton and boll weevil eradication, which can allow producers to extend the growing season.
Cotton producers have wondered if changes should be made in recommended planting dates for their regions — April 20 to May 10, for west Tennessee, and May 5 to May 15 for the Bootheel.
“Farmers ask if they should push the envelope and plant cotton a little later,” Craig said. “Most of the time, when we plant in late April, cotton comes up sick, we have trouble getting a stand, and there's a lot of seedling disease. The later we waited to plant, the better it grew off. So why not wait?”
As it turned out, 2003 turned out to be an exceptional year for later-planted cotton. West Tennessee produced a record average yield of 806 pounds per acre, although 50 percent of the cotton acreage was planted after the recommended planting dates for the region.
Craig's study reflected what was happening in the field. “With each subsequent planting date, yield increased. Even my full-season variety continued to improve the later we planted. We had a tremendous growing season and were very lucky on the far end. I was disappointed that our cotton planted May 13 didn't do any better than it did.”
Nonetheless, Craig believes the study will eventually prove that west Tennessee planting dates are very reliable. “I tell growers we were very lucky. We were fortunate with the harvest season. We did not get a killing freeze until November.”
Phipps' study showed reductions in yield the longer a farmer waited to plant in 2001 and 2003. In 2002, a long growing season, yield was fairly flat across all the planting dates.
The three-year average showed a decrease in yield with each later planting date, according to Craig's summarization of Phipps' study. “From May 15 to June 1, the average decrease was 15 pounds for each day after May 15. That reinforces the recommendations that May 15 is a good cutoff for the Bootheel.
Craig believes west Tennessee cotton producers will be hurt more often than helped by June cotton plantings. “The data say we will have an early freeze one of these years. The last one was Oct. 9, 2000. Since the release of Bt cotton, we have had one early freeze in west Tennessee. So keep that in mind. Many things can go wrong with late plantings.”
Another component of Craig's study was evaluating plant population by planting date. “A lot of farmers ask if one plant per foot in April-planted cotton is as good as three plants per foot in late-May, early-June planted cotton. They want to know if they would be better off saving that crop or replanting.”
The studies were located in Jackson and Milan, Tenn., and began in 2003. However, excessive rain in the spring left Craig with only one location in Milan. Phipps had a similar study in southeast Missouri.
One year of data at Milan indicated cotton producers can harvest stable yields between 20,000 and 70,000 plants per acre. “You can make good cotton at one plant per foot,” Craig said.
The Bootheel study also showed stable yields as low as one plant per 1.5 feet of row, according to Craig. “I think the bottom line is thin stands can do okay. But you want to give yourself some insurance at planting. If you have four plants per foot, you can lose two plants per foot and have an adequate stand.”
The combination of early planting and low plant density can be tricky, according to Craig. “We see a lot of branching, a lot of fruit on the outer positions. What we gain in compensation, we lose in maturity. It takes longer for the plant to mature. It's also hard to get this big plant through the picker.
An optimum planting density of three plants per foot planted June 2 was not sporting many blooms by July 22, according to Craig. “I'm not putting my money on this plant as the clear winner.”
A plant population of five plants per foot will create stovepipe-shaped plants,” noted Craig. “It is a little later before fruiting starts up on the plant. Again, maturity is delayed. In addition, five plants per foot is going to hurt your pocketbook (because of higher seed costs).”
The take-home message is that a lower plant population can turn out okay,” Craig said. “Still, you want to shoot for two to three plants per foot. That's our most optimum plant population. It's consistent and a lot easier to manage, and it can give you some wiggle room if something happens.”
Results of the study and other information are available at www.utcrops.com.