Potassium is essential in the growth and development of the cotton plant. Potassium is essential for many of the enzyme systems in the plant, plays a role in reducing the incidence and severity of the wilt disease, increases water efficiency, affects the speed of almost all plant biological systems, and affects fiber properties such as micronair, length, and strength. Uptake of potassium increases during early boll set with some 70 percent of total uptake occurring after first bloom.
Potassium deficiency symptoms appear as a yellowish-white mottling to a light-yellowish-green color with yellow spots appearing between the veins. The centers of these spots die, and numerous brown specks occur at leaf tips, around margins, and between veins. The tips and margins break down first and curl downward. As symptoms progress, the whole leaf becomes reddish brown, dries, and becomes scorched and blackened in appearance. Premature dropping of leaves is also characteristic and may affect boll development resulting in bolls not maturing or only partially opening and containing poor quality fiber.
The most common source of potassium is muriate of potash (0-0-60). Other sources include potassium sulfate and potassium nitrate.
Follow soil test recommendations where yield potential is less than two bales per acre. If a field has a realistic yield goal of two bales or more, increase the potash rates by 50 percent over the recommendation given on a soil test report from the MCES Soil Testing Laboratory. In some areas of the Delta bordering the brown loam hills, there seems to be some soils that historically test low in potassium, regardless of the use rates. Fields on these soils generally tend to have wilt problems or problems with premature cutout and premature leaf drop. Research is being conducted on these soils to determine the possible cause of these problems and develop corrective recommendations. At this time, it appears that increasing the potassium rate by an additional 50 percent of the MCES soil test recommendation and splitting material into two applications may be beneficial on these soils.
Some research at the Delta Research and Extension Center indicates that there may be some potential for the deep placement of potassium in cotton on soils with subsoils that test low or very low in potassium. These treatments tend to show more potential on soils that do not have a low pH in the subsoil layers and where treatments are made far enough in advance of planting to allow the beds to properly settle.
Potassium fertilization of cotton should receive more attention from farmers.
STARKVILLE, Miss. -- Rain, cool weather, more rain and some wind have slowed cotton maturation, but since the crop was a little behind schedule, the damage may be less than if harvest were already underway.
Darrin Dodds, cotton specialist with the Mississippi State University Extension Service, said recent weather is causing some yield loss, but it is hard to estimate how much.
“Being late to a degree helped the crop because rain did not string out open cotton, but given that we are running out of heat, we may have been better off with an earlier crop that had been defoliated and was standing up when the rain came,” Dodds said.
STARKVILLE, Miss. -- Cotton will always have challenges, but few of them will ever compare to the boll weevils that thrived in Mississippi from 1904 until 2009.
“It is nearly impossible for this younger generation of consultants, scouts and growers to understand how hard boll weevils were to control and how much boll weevil control hurt beneficial insects and complicated cotton management,” said Will McCarty, who served as the Mississippi State University Extension Service cotton specialist during “the boll weevil wars.”
MACON, Miss. -- Farmers' independent natures make them strong, but when agricultural producers join forces, they can take success to the next level.
Darrin Dodds, cotton specialist with the Mississippi State University Extension Service, commended Mississippi farmers for their efforts to unite in the battle to eradicate boll weevils from the state.
“Historically, boll weevils were the prime pest in cotton fields. To control them, it took numerous pesticide applications,” he said. “Those treatments were costly and ate into the growers’ profit margins.”
STARKVILLE, Miss. -- Mississippi’s row crops have had enough rain, and most fields just need sunshine.
Erick Larson, grain crops specialist with the Mississippi State University Extension Service, said corn is mature and will gain no benefit from additional moisture. In the first couple of weeks of August, skies were overcast or rain was falling across most of the state.
STARKVILLE, Miss. -- Tropical Storm Cindy did not help the state's cotton crop that struggled with cool and wet weather all spring.
Darrin Dodds, cotton specialist with the Mississippi State University Extension Service, said in mid-June, cotton received about a week of the heat and sun it needs to thrive. Weather before that was not ideal, and rain remains in the forecast.