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

Close-up of a cotton plant.
Filed Under: Agriculture, Cotton August 30, 2021

STARKVILLE, Miss. -- When the calendar turns to September, many who call Mississippi home long for cooler temperatures to relieve the summer’s heat, but the state’s cotton growers want high temperatures and dry weather to drag into October.

Water stands in a corn field
Filed Under: Crops, Corn, Cotton, Soybeans, Disaster Response June 24, 2021

STARKVILLE, Miss. -- MSU Extension agents will be assessing agricultural damage from early-June flooding until well into July, but preliminary estimates indicate losses could break records.

The 2019 Yazoo Backwater Area flood caused $617 million in crop damage alone. It looks like the more recent flood will exceed those losses.

Heavy rainfall, primarily north of U.S. Highway 82, throughout the second week of June waterlogged crops during critical growth stages. Flooding caused complete or partial losses in many fields.

 A man in a hat kneels among straw to point at tiny plants.
Filed Under: Crops, Corn, Cotton, Rice, Soybeans May 20, 2021

Because it is the first crop planted starting in March, Mississippi corn is in much better shape than other row crops struggling with the challenges of wet, cool weather.

Graphic showing 2021 planting intentions
Filed Under: Agriculture, Corn, Cotton, Rice, Soybeans April 1, 2021

STARKVILLE, Miss. -- Mississippi row crop growers are planning to plant more soybeans and corn in 2021 than they did last year but not as much cotton, rice or hay.

The National Agricultural Statistics Service, a branch of the U.S. Department of Agriculture, publishes its planting intentions report each year at the end of March. This report provides a state-by-state estimation of how many acres of corn, soybeans, wheat and cotton farmers will plant in the upcoming growing season.

Filed Under: Agriculture, Corn, Cotton, Grains, Rice, Soybeans, Sweet Potatoes, Agri-tourism, Beekeeping, Equine, Goats and Sheep, Poultry, Swine, Turfgrass and Lawn Management, Vegetable Gardens, Forestry February 2, 2021

STARKVILLE, Miss. -- Each February marks the occasion for producers to share their research and programming needs with Mississippi State University agricultural specialists in person.

To comply with COVID-19 social distancing guidelines, the opportunity will be extended virtually this year.

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

Your Extension Experts

Portrait of Dr. Darrin Dodds
Professor and Head
Cotton Agronomics
Assistant Professor