Morning Ag Clips logo
  • Subscribe ❯
  • PORTAL ❯
  • LOGIN ❯
  • By Keyword
  • By topic
  • By state
  • Home
  • Events
  • Jobs
  • Store
  • Advertise
  • Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer
  • Subscribe to our
    daily email
    ❯
  • Portal Registration❯
  • Login❯
  • policy
  • tractors & machinery
  • education
  • conservation
  • webinars
  • business
  • dairy
  • cattle
  • poultry
  • swine
  • corn
  • soybeans
  • organic
  • specialty crops
  • Alabama
  • Alaska
  • Arizona
  • Arkansas
  • California
  • Colorado
  • Connecticut
  • Delaware
  • Florida
  • Georgia
  • Hawaii
  • Idaho
  • Illinois
  • Indiana
  • Iowa
  • Kansas
  • Kentucky
  • Louisiana
  • Maine
  • Maryland
  • Massachusetts
  • Michigan
  • Minnesota
  • Mississippi
  • Missouri
  • Montana
  • Nebraska
  • Nevada
  • New Hampshire
  • New Jersey
  • New Mexico
  • New York
  • North Carolina
  • North Dakota
  • Ohio
  • Oklahoma
  • Oregon
  • Pennsylvania
  • Rhode Island
  • South Carolina
  • South Dakota
  • Tennessee
  • Texas
  • Utah
  • Vermont
  • Virginia
  • Washington
  • West Virginia
  • Wisconsin
  • Wyoming

Morning Ag Clips

  • By Keyword
  • By topic
  • By state
  • policy
  • tractors & machinery
  • education
  • conservation
  • webinars
  • business
  • dairy
  • cattle
  • poultry
  • swine
  • corn
  • soybeans
  • organic
  • specialty crops
  • Home
  • Events
  • Jobs
  • Store
  • Advertise
Home » Soybean rust develops ‘rolling’ epidemics
corn soybeans
SOYBEAN HEALTH ...

Soybean rust develops ‘rolling’ epidemics

Studies suggest that air masses moving from the south could sweep up rust spores

PUBLISHED ON September 4, 2017

soybean rust on plants in Florida
soybean rust on plants in Florida
Soybean rust on plants in Florida. (Courtesy of University of Illinois)

URBANA, Ill. — Although Midwestern soybean growers have yet to experience the brunt of soybean rust, growers in the southern United States are very familiar with the disease. Every year, the fungus slowly moves northward from its winter home in southern Florida and the Gulf Coast states, and eventually reaches Illinois soybean fields—often just before harvest.

Research shows there is a possibility the disease could jump much longer distances and reach the Midwestern soybean crop earlier in the growing season. Studies suggest that air masses moving from the south could sweep up rust spores from infected plants (kudzu or soybean) and transport them hundreds of miles north earlier in the season, potentially endangering the Midwestern soybean crop.

This could be happening right now as the storm system that created Hurricane Harvey moves north, according to Glen Hartman, a USDA Agricultural Research Service plant pathologist and professor in the Department of Crop Sciences at the University of Illinois. After all, hurricanes have been responsible for long-distance movement of rust spores in the past; scientists think Hurricane Ivan brought soybean rust to the United States from Colombia in 2004.

Although long-distance movement can and does happen, short-distance spore movement has been responsible for most of the annual northward spread of the disease since 2005. Hartman thinks this short-distance movement has been occurring as usual this season and, barring any unusual fallout from Hurricane Harvey, he expects to see rust showing up in Illinois soybean fields late in the 2017 season.

It is this short-distance movement that intrigues Hartman; he says predictions of long-distance spread haven’t taken real-world spore movement into account. Without knowing the number of rust spores that actually escape from the canopy and the conditions that favor spore dispersal, long-distance spread models could be inaccurate. So, in a recent study, Hartman and his colleagues placed two kinds of spore-collecting traps in, around, and above rust-infected soybean fields in Alabama, Georgia, and Florida. The team also measured environmental data, including air temperature, relative humidity, wind speed and direction, precipitation, and leaf wetness.

The majority of spores stayed within the canopy, but a proportion (one-third to one-half) floated above. Spores moved laterally away from the field, too, but most stayed within 50 feet, with about half as many moving out to 200 feet.

These numbers explain how short-distance spread of this disease typically works. Rust might spread within a field, then jump to a nearby patch of its alternative host, kudzu. Considering how much kudzu is spread around the south, it’s a good bet another soybean field is within a couple hundred feet. From there, it jumps again, moving incrementally to the north. In an average summer, Hartman says, soybean rust rolls up from the south at a rate of about 30 miles a day.

Hartman’s study also identifies environmental factors that favor or impede short-distance movement of rust spores. Using a statistical approach known as machine learning, the team found that spores went farther in hot and windy conditions, and stayed closer to the canopy in humid, wet conditions.

“What really drives local infection is humidity and moisture,” Hartman says. “Those are good conditions for fungal infection and production of spores. When it rains, it washes the spores out of the leaf lesions, so they’re not available for long-distance transport. But then the fungus just forms new spores that are ready for transport on a dry and windy day.”

The study explains short-distance transport, but how do the results inform predictions of long-distance movement?

“I think the study gives a good idea of rust spore counts in the atmosphere in and above the soybean canopy and a distance away from an infected field. There is a lot of variation in the number of spores in that air space,” Hartman says. “If you think of the airspace beyond the field, the dilution factor is huge.”

In other words, the chances of spores making it out of the canopy and picked up by updrafts for long-distance movement might be lower than assumed. And the chances are lower still if you consider what it’s like for spores to survive in high-elevation air currents.

“Spores in these high-elevation air masses are exposed to temperature extremes and to UV radiation. Not many spores survive that, although those that are darkly pigmented may have a better chance. Soybean rust spores have very little pigment, and lightly pigmented spores are very susceptible to UV,” Hartman says.

New models will need to incorporate Hartman’s findings to better predict the chances of long-distance movement of soybean rust throughout the U.S. and other parts of the world.

For further information regarding soybean rust, Hartman suggests the soybean rust website, http://sbr.ipmpipe.org. He also encourages Midwestern soybean growers to contact their local Extension office if they see symptoms of rust developing earlier than usual.

The article, “Prediction of short-distance aerial movement of Phakopsora pachyrhizi urediniospores using machine learning,” is published in Phytopathology. Hartman’s co-authors, Liwei Wen and Roger Bowen are also from the University of Illinois.

— Lauren Quinn, University of Illinois College of Agricultural, Consumer and Environmental Sciences

For more news from Illinois, click here.

RECOMMENDED ARTICLES

Tar spot disease of corn spreading to more Nebraska counties
October 16, 2022

LINCOLN, Neb. — Tar spot, caused by the fungus Phyllachora maydis, was confirmed in eight eastern Nebraska counties in October 2021. As expected, the fungus overwintered and disease redeveloped in 2022 as field conditions became favorable in those same areas. The fungus has spread to corn fields in several new counties (highlighted yellow), as well […]

Southern rust still poses a threat to Georgia corn crop
July 21, 2022

ATHENS, Ga. — Georgia’s corn producers should be on alert for southern corn rust, a devastating disease that has been found in several Georgia counties this year, exacerbated by a warm La Niña winter and hot, humid conditions so far this season. Bob Kemerait, a professor of plant pathology with the University of Georgia College […]

Fungicide resistance and management of frogeye leaf spot of soybean in Nebraska
June 26, 2022

LINCOLN, Neb. — Frogeye leaf spot (FLS) of soybean is an important disease in Nebraska. While FLS has not yet been confirmed in the state during the 2022 growing season, producers should expect to see disease symptoms in the next few weeks. The disease can cause significant yield loss but there are effective management options […]

Colorado wheat disease
June 08, 2021

FORT COLLINS, Colo. — Stripe rust was found at low incidence and low disease severity in several northeastern counties (Figure 1). The past two weeks of cool, wet weather has been favorable for disease development.  The extended hot weather forecasted over the next week should help control disease development since stripe rust spores germinate poorly […]

First cucurbit downy mildew spores identified in air samples in Allegan County
May 31, 2021

EAST LANSING, Mich. — Cucurbit downy mildew spores have been verified in air samples using a Burkard volumetric spore trap in Allegan County, Michigan. A cucurbit downy mildew disease outbreak on cucumber plants has not been reported in Michigan at this time. While it is concerning that an influx of sporangia has been detected, these sporangia must land […]

Spread the word

Browse More Clips

Dairy producers can enroll for 2018 coverage

cattle in missouri pasture

Cattle on feed inventory remains above a year ago

Primary Sidebar

MORE

ILLINOIS CLIPS

Glen "GB" Brandt Prize for Ag Entrepreneurism
Ag entrepreneurism prize nominations close Feb. 10
January 31, 2023
iCOVER
USDA grant funds innovative cover cropping project
January 31, 2023
women caring for the land
Register for Ag Women Engage Conference
January 30, 2023
ALB charts course for 2023 in leadership and programs
January 30, 2023
USDA appoints members to Cattlemen’s Beef Promotion and Research Board
January 30, 2023
  • Trending
  • Latest

YOU MIGHT ALSO LIKE...

Scholarship deadline quickly approaching
January 30, 2023
First-of-its-kind research identifies $400 million in unrealized soybean value
January 30, 2023
SARE Video: Managing Weeds in Organic Row Crops
January 30, 2023
high corn yields
Three major pieces to high corn yields
January 29, 2023
Corn growers learn latest crop practices, recognize top yields
January 29, 2023

Footer

MORNING AG CLIPS

  • Contact Us
  • Sponsors
  • About Us
  • Advertise with Us
  • Privacy Statement
  • Terms of Service

CONNECT WITH US

  • Like Us on Facebook
  • Instagram
  • LinkedIn
  • Twitter
  • YouTube

TRACK YOUR TRADE

  • Markets & Economy
  • Cattle Updates
  • Dairy News
  • Policy & Politics
  • Corn Alerts

QUICK LINKS

  • Account
  • Portal Membership
  • Just Me, Kate
  • Farmhouse Communication

Get the MAC App Today!

Get it on Google Play
Download on the App Store

© 2023 Morning Ag Clips, LLC. All Rights Reserved.