A recent Beltwide study forum led by J.C. Banks and Craig Bednarz, on the importance of the first 40 days to final cotton production, has generated interest in these production practices, but Virginia Cotton Specialist, Joel Faircloth reminds Virginia/Carolina growers that these 40-day recommendations will vary somewhat for different states.
Speaking at the recent Virginia Cotton Producers Annual Meeting, Faircloth compared the first 40 days of a cotton plant's health and growth to that of a child. “We all want to give our children the best chance possible to succeed later in life, so we provide the best inputs we can, but every child and every situation is different — so is every cotton crop, he contends.
Planting date is more critical in Virginia than in areas of the South where the growing season is longer, he notes. “When you don't plant on time, you are shortening the bloom season. In a normal year, the last affective bloom date in Virginia is Aug. 15, meaning after that time those bolls typically aren't going amount to too much.
In Virginia, we recommend you have a soil temperature at 3-inch depths, at 10 a.m. of 60-65 degrees F. We also recommend a 5-7 day warming trend following planting and no heavy, packing rain.
This is critical not only to reduce crusting, but because soil moisture can significantly reduce soil temperature, Faircloth says. He points out that recent research conducted by Virginia Tech Plant Pathologist Pat Phipps indicates that temperatures nearer the 60 degree F line, followed by warm weather, may be as good as 65 degrees F. With that range and a range of 30,000 to 60,000 seed per acre, growers have some flexibility in planting.
In Virginia, 66 cotton varieties were tested in 2005, though Faircloth stresses that no recommendations are based on one-year of data. “Look at multi-year variety test results and multiple locations, when possible, the Virginia specialist says. “This may be the most critical decision a grower makes, because it determines what will happen the rest of the year and what the yield potential is for the year,” he explains.
In general, Roundup Ready, with and without Bollgard trait, produced higher yields than other technologies. “We are confident over the next few years varieties will be developed that contain new technologies and produce comparable or better yields,” Faircloth contends.
The top yielding Roundup Ready Flex varieties produced about 100 pounds per acre less than the top producing varieties without the new technology. None topped 1,600 pounds of lint per acre, nor produced 44 percent lint. The top Flex variety, Stoneville ST 4664 RF did produce high yields and high quality cotton, but not comparable to other varieties in the one year test.
The next three top-yielding flex varieties, Deltapine 108RF, Royster-Clark VCX612 and Deltapine 110RF all produced yields within 150 pounds of the top yielding non-flex variety.
Two Bollgard Roundup Ready varieties, Deltapine DP 444 BG/RR and Deltapine 454 BG/RR produced the highest yields and all had high lint percentage and quality scores. Deltapine 434 RR, Deltapine DP 393, PhytoGen PHY 370WR and PhytoGen 310 R all produced yields within 100 pounds of the top variety in the test.
In three-year variety tests in Virginia, Deltapine DP393 had the highest overall lint yield and quality scores. Deltapine 444 BG/RR, Deltapine432 RR, Bayer CropScience FM 989 BR, and Stoneville, ST 4892 BR, all performed comparably to the top variety in multiple year, multiple site tests.
For Virginia and other states on the northern edge of the cotton-producing belt, the use of plant growth regulators is not always a yield-enhancing practice. “In Virginia, I don't think we have a place for plant growth regulators in the first 40 day period,” Faircloth contends.
“We know that plant growth regulators enhance cotton maturity, which can be extremely important in Virginia, but we don't want to cheat early season cotton varieties out of their potential by applying plant growth regulators too early or at too high rates. Especially on top performing varieties, like Deltapine 444, we don't want to rob them of their production potential,” the Virginia specialist says.
“If you apply plant growth regulators too early, you can rob the plant of its yield potential. We've seen it both ways — increases in yields and losses in yields,” Faircloth explains.
Cover crops are critical to the first 40 days of a cotton plant's life, according to Faircloth. First, cover crops build up organic matter. And more importantly, cover crops reduce sand blasting, which on Virginia's light, sandy soils compound all early season problems, especially thrips.
“Just like you don't want your kids to get sick and interfere with their growth potential, you don't want your cotton plants to get sick,” Faircloth notes. In Virginia, the common early season diseases are rhizoctonia, commonly called sore shin, and pythium or damping off diseases.
Virginia Tech Plant Pathologist Pat Phipps says the first line of defense against these, and other, early season diseases is high quality seed that are coated with seed protectant fungicides and insecticides. Seed with cool germination of 80 percent or higher are desirable and seed with cool germ levels below 60 percent should be avoided, he says.
In a cool, wet environment, or in fields with a long history of disease problems, in-furrow treatment with fungicides may be needed to ensure seedling health, Faircloth adds.
The primary early season insect problem is thrips. Over the past 5-6 years cotton losses to insects and cotton losses to thrips are very close together, Faircloth points out. Seed treatments look promising for thrips control, and Temik has supplied consistently good control of thrips, the Virginia cotton specialists says. “Ames Herbert, entomologist and head of Virginia Tech's Integrated Pest Management Program has done a good job of demonstrating the value of protecting seedling cotton from thrips injury,” Faircloth adds.
Taking more and more peanuts out of the rotation (Virginia is down to less than 20,000 acres of peanuts) will likely cause an increase in nematode problems in cotton, Faircloth warns. Nematodes restrict roots from taking up nutrients and damage from these pests is frequently diagnosed as soil fertility or other type damage, he points out.
Managing weeds in the first 40 days is arguably the most effective way to maintain cotton plants at their maximum yield potential. Each week after planting a grower delays making his cotton weed free, costs over 260 pounds of cotton per acre, according to recent trials conducted by North Carolina State researchers John Wilcut and Alan York.
In the first 40 days, method of glyphosate application is critical in Roundup Ready cotton. “Post directed application of glyphosate is legal, but if the application is sloppy and the herbicide hits high on the plant, you may see yield reductions,” Faircloth says. “It all depends on how many heat units you get to compensate for the bolls you lose with off label or sloppy post-directed applications,” he explains.
The single highest input cost for Virginia cotton growers is soil fertility. With fertilizer costs, especially nitrogen, soaring, applying optimum amounts is critical to the bottom line.
Proper liming is critical in Virginia cotton, because it is among the most sensitive to low soil pH of crops grown in Virginia. Cotton will grow best in the state at pH levels in the 5.8-6.5 range.
“Last year we saw a lot of problems from potassium deficiency,” Faircloth notes. On deep sandy soils, most often with high nematode levels, we saw some very bad situations with potassium deficiency, he says. On these deep sand soils, growers may need up to 150 pounds of potassium per acre, he concludes.