By Daren Mueller and Erika Saalau, Department of Plant Pathology and Microbiology
Over the past several weeks, we have received several samples in the Plant and Insect Diagnostic Clinic with irregular blotches and necrotic lesions on the pods.
After eliminating all of the known causes, a sample was screened for several common bean viruses*. The sample came back strongly positive for tobacco streak virus (TSV).
This virus was first identified in Iowa and the United States in 1967. The soybean plants with “pods showing necrotic spots” were noticed in late-planted soybeans. From this earlier report, TSV reduced the number of pods per plant and delayed seed maturation. Other symptoms include stunting, bud blight, leaf mosaic (mottling), dwarfed leaves and stem discoloration. This virus is mainly seed transmitted and several thrips species have been reported as TSV vectors.
If you have soybean pods with similar symptoms, you can send them to the ISU Plant and Insect Diagnostic Clinic. Confirmation of TSV costs $50.
Figure 1. Tobacco streak virus symptoms on soybean pods.
*Testing service provided by Agdia, Inc.
Daren Mueller is an assistant professor in the Department of Plant Pathology and Microbiology. He can be reached at 515-460-8000 or e-mail dsmuelle@iastate.edu. Erika Salaau-Rojas is a diagnostician in the Plant and Insect Diagnostic Clinic. You can reach her at 515-294-0581 or e-mail pidc@iastate.edu.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on September 27, 2013. The information contained within may not be the most current and accurate depending on when it is accessed.
Daren Mueller Professor
Daren Mueller is an associate professor and extension plant pathologist at Iowa State University. He is also the coordinator of the Iowa State Integrated Pest Management (IPM) program. Daren received his bachelor's degree from the University of Wisconsin-Madison in 1996, and his master's degree a...