By Jamie Martin
In 2024, Ohio's soybean crops faced unique disease challenges, largely due to weather conditions and insect vectors. The concept of the "disease triangle" explains how diseases develop in crops.
For a disease outbreak to occur, three conditions must be met: a favorable environment, a susceptible host, and the presence of a disease-causing pathogen. Dry weather in 2024 disrupted the usual spread of diseases by eliminating the favorable environment necessary for many pathogens.
Some regions still experienced disease outbreaks, mainly due to insect vectors transmitting pathogens to susceptible plants.
"It appears that most of the soybeans in Ohio were relatively clean this growing season and had minimal disease impacts. What have you seen, and what is being reported by OSU Extension Educators across the state?" said Dr. Horacio Lopez-Nicora, a soybean pathologist and nematologist from Ohio State University Extension.
One disease stood out—Soybean Vein Necrosis Virus (SVNV). This virus, first identified in the U.S. in 2009, was found in almost every field they visited this year.
SVNV is transmitted by thrips, an insect vector. The virus causes distinct symptoms in infected plants, starting with yellowing and bronzing of the veins, which eventually become necrotic.
Diagnosing SVNV requires laboratory testing, but its symptoms are quite recognizable. While SVNV has been widely observed, there is still limited research on its overall impact on crop yields.
A small percentage of SVNV cases are seed-borne, but thrips are the primary vector spreading the disease. Weather conditions played a significant role in the disease's prevalence this year.
Ohio experienced a mild winter and a dry spring, both of which promote the reproduction of thrips. As a result, the virus spread more easily, particularly in drought-stressed soybean plants.
The combination of a susceptible host (drought-affected soybeans), a virulent pathogen (SVNV), and a favorable environment for thrips created ideal conditions for disease spread in 2024.
The disease triangle remained relevant, as the vector thrips transmitted the virus from plant to plant, leading to SVNV's presence across Ohio fields. More research is needed to understand the full impact of this virus.
Photo Credit: gettyimages-gilaxia
Categories: Ohio, Crops, Soybeans