You are here

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.

Print Friendly, PDF & Email

News

Cotton with sprouting plants lies on muddy ground.
Filed Under: Agriculture, Crops, Corn, Cotton, Grains, Soybeans October 5, 2018

Most of Mississippi’s corn and rice crops had been harvested when prolonged, late-September rains soaked much of the state, but the wet weather could not have come at a worse time for soybeans and cotton.

A pink cotton bloom sits among green leaves.
Filed Under: Cotton July 27, 2018

As most cotton across Mississippi is setting bolls ahead of schedule this year, some fields look fantastic and others are struggling, depending on the weather and irrigation.

A wife and husband stand in a field with cotton rows.
Filed Under: Agriculture, Crops, Corn, Cotton, Peanuts, Soybeans July 26, 2018

Lonnie Fortner has been named the Mississippi winner of the 2018 Swisher Sweets/Sunbelt Expo Southeastern Farmer of the Year award.

Green baby cotton plants poke through soil.
Filed Under: Crops, Cotton May 18, 2018

STARKVILLE, Miss. -- Growers may be on their way to planting more cotton in Mississippi soil than they have in 11 years, despite a late start.

Darrin Dodds, cotton specialist for the Mississippi State University Extension Service, estimated that growers will plant 700,000 acres of cotton this year. If that much gets harvested, it will be the best total since 2006, when the state produced 1.2 million acres of cotton. Last year, Mississippi cotton producers harvested 625,000 acres.

Filed Under: Commercial Fruit and Nuts, Green Industry, Organic Fruit and Vegetables, Other Vegetables, Corn, Cotton, Nuts, Peanuts, Soybeans, Equine, Goats and Sheep, Poultry, Lawn and Garden, Forestry, Seafood Economics, Seafood Harvesting and Processing March 7, 2018

ELLISVILLE, Miss. -- Mississippi State University representatives met with agricultural clients in Ellisville recently to discuss research and education needs for 2018. More than 115 individuals attended this year's event.

Watch

Farmweek, Entire Show, October 9, 2015
Farmweek

Season 39 Show #14

Thursday, October 8, 2015 - 7:00pm
Farmweek Entire Show,  September 4, 2015
Farmweek

Season 39 Show #09

Thursday, September 3, 2015 - 7:00pm

Contact Your County Office

Upcoming Events

Your Extension Experts

Extension/Research Professor
Cotton Agronomics