Soybean Rust Discovered in Louisiana

Growers urged to monitor fields and contact experts as disease poses major threat to yields

Apr. 18, 2026 at 6:38am

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A bold, highly structured abstract painting in muted earth tones, featuring sweeping geometric arcs, concentric circles, and precise botanical spirals, conceptually representing the complex natural forces behind the soybean rust fungus and its potential to spread across agricultural regions.An abstract visualization of the complex life cycle and spread mechanisms of the soybean rust fungus, a growing threat to America's vital soybean crop.Baton Rouge Today

Asian soybean rust, a devastating fungal disease that can cause up to 90% crop losses, has been detected for the first time in the United States. The disease was found in research plots at Louisiana State University near Baton Rouge, prompting warnings for soybean growers to be vigilant and work quickly with local experts to manage the outbreak.

Why it matters

Soybean rust poses a major threat to the U.S. soybean industry, which produces over 120 million metric tons annually and is valued at over $40 billion. Early detection and rapid response are critical to minimizing the impact, as the disease can spread quickly via wind-borne spores and overwinter in warm climates like the American South.

The details

Laboratory tests by the USDA confirmed the presence of the Phakopsora Pachyrhizi fungus, which causes soybean rust, in two research plots at Louisiana State University. Soybean rust leads to foliar lesions and premature defoliation, potentially resulting in yield losses up to 90% if not quickly treated with fungicides. While the current impact is expected to be minimal since most soybeans have already been harvested, the disease could potentially overwinter in the South on substitute hosts like kudzu and spread to other regions next growing season.

  • The disease was first detected in mid-November 2026 at the LSU research farm near Baton Rouge.
  • Soybean rust was previously found in South America in 2004, and USDA officials have predicted its arrival in the U.S. for several years.

The players

USDA's Animal & Plant Health Inspection Service

The federal agency that confirmed the presence of the soybean rust fungus through laboratory testing.

United Soybean Board

The organization that has warned about the threat of soybean rust and the need for early detection and management.

Louisiana State University

The university that operates the research farm where soybean rust was first detected in the United States.

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What’s next

USDA officials and experts are urging soybean growers across the country to closely monitor their fields and contact local extension agents or university plant diagnostic centers if they suspect the appearance of soybean rust. Rapid response with appropriate fungicide treatments will be crucial to limiting the spread and impact of this devastating disease.

The takeaway

The discovery of soybean rust in the U.S. represents a major threat to the nation's soybean industry. Growers must remain vigilant, work closely with agricultural experts, and be prepared to act quickly to protect their crops from this highly destructive fungal disease that could potentially spread across the country.