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Potassium Deficiency

In cotton, foliar symptoms of potassium deficiency that occur before peak bloom are similar to potassium deficiency symptoms found on other broadleaf crops. Interveinal yellowing first occurs on older leaves progressing to necrotic patches developing at leaf margins as conditions worsen. In many soils potassium supply is sufficient until peak bloom. At that time rapid dry matter accumulation in bolls begins, especially when a crop is fruited properly. At this point it is difficult for the soil to supply adequate potassium to meet the increased daily demand.

Late-season potassium deficiency results in foliar symptoms that differ from early-season deficiency. During and after peak bloom, deficiency symptoms will first appear on the younger mature leaves in the upper one-third of the plant. This is primarily because the developing bolls are the stronger sink for potassium being taken up from the soil each day. These symptoms will begin as a slight interveinal yellowing that will rapidly change to a bronze-orange color. These leaves then generally curl downward and will become thick, and necrotic patches will occur at the margins. As this problem develops boll retention decreases, and premature defoliation generally occurs. These symptoms can be so devastating that symptoms of late-season potassium deficiency are sometimes mistakenly attributed to a plant disease, especially Verticillium wilt. The two symptoms are distinct and a trained eye can spot the difference immediately. Verticillium wilt causes necrotic lesions between leaf veins that have well-defined borders and will generally be a brighter yellow than will potassium deficiency; then, they develop a rich brown color. The tell tail difference will be in the discoloration of the mainstem vascular tissue. If the foliar symptoms are confusing, cut the main stem of the plant in cross section. If the stem is filled with a dark streaking discoloration, the problem is Verticilium wilt. If the vascular tissue is clean, the problem is probably potassium deficiency. A tissue test cannot always tell the difference because Verticilium wilt will plug the stem preventing proper uptake and distribution of potassium, and other nutrients throughout the plant. It is interesting to note that proper potassium fertilization has been shown to reduce the incidence and severity of Verticillium wilt.

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News

Picked cotton sits in large green and red bales.
Filed Under: Agricultural Economics, Corn, Cotton, Rice, Soybeans December 19, 2017

STARKVILLE, Miss. -- The 2017 production value of Mississippi’s four largest row crops is forecasted to outperform the previous year by more than 7 percent.

Brian Williams, agricultural economist with the Mississippi State University Extension Service, predicted the combined value of soybeans, cotton, corn and rice will be nearly $2.1 billion this year. The total projected value for all agronomic crops is $2.5 billion, which would be a 6.4 percent increase over the $2.4 billion value reached in 2016.

Filed Under: Crops, Corn, Cotton, Rice, Soybeans November 15, 2017

STARKVILLE, Miss. -- Cover crop usage is gaining momentum on Midsouth farms and will be a major focus of the 2017 Mississippi State University Row Crop Short Course.

The MSU Extension Service will host the course at the Mill Conference Center in Starkville Dec. 4-6.

A closed boll is seen on a cotton plant growing in a field.
Filed Under: Agricultural Economics, Cotton September 15, 2017

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.

Mississippi Boll Weevil Management Corp. representative Mike Mullendore checks one of the cone-shaped traps located near a Mississippi State University research field on June 27, 2017. The traps evolved from U.S. Department of Agriculture research at the Robey Wentworth Harned Laboratory, commonly known as the Boll Weevil Research Lab at MSU. (Photo by MSU Extension Service/Linda Breazeale)
Filed Under: Cotton, Insects-Crop Pests August 24, 2017

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.”

Award-winning farmer Paul Good examines cotton growing in Noxubee County during a Mississippi State University field tour on July 12, 2017. Good said he remembers a time when farmers did not grow cotton in the area, mostly because of boll weevils. (Photo by MSU Extension Service/Linda Breazeale)
Filed Under: Cotton, Insects-Crop Pests August 24, 2017

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.”

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