Project Details:

Title:
Investigating SDS and Fusarium Root Rot Resistance, Preventative Seed Treatments, and Pathogen Variability in Kansas

Parent Project: This is the first year of this project.
Checkoff Organization:Kansas Soybean Commission
Categories:Soybean diseases
Organization Project Code:1948
Project Year:2019
Lead Principal Investigator:Christopher Little (Kansas State University)
Co-Principal Investigators:
Keywords:

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

Sudden death syndrome (SDS) is a fungal disease of soybean that causes foliar spots, root decay, and yield loss of up to 100% in some fields with no pods visible at maturity, but normally yield losses average 5-15%. In Kansas, annual estimates provided by extension Row Crops Pathology range from trace levels to more than 250k bu of yield loss. However, SDS is a perennial cause of yield loss in the Kansas River Valley, for example. More recent data shows these numbers are on the rise. The disease is considered one of the top yield robbers of soybean and is now widespread across the Midwest soybean growing region. It is caused by the soilborne pathogen, Fusarium virguiliforme. SDS is a good descriptor for the disease in that normal plants may abruptly turn yellow and die. SDS also can weaken the host making it more susceptible to abiotic stresses (e.g. drought), pest infestation (e.g. spider mites), and other diseases (e.g. charcoal rot). Likewise, Fusarium root rots cause perennial yield losses in Kansas and represent an underexplored group of pathogens in the state. Many of the same Fusarium pathogens cause seedling disease as well. The level of yield losses to these diseases are difficult to quantify due to their soilborne nature and occurrence during or after abiotic stresses. Therefore, the objectives of this proposal are: (1) Screen adapted Kansas germplasm, sequenced plant introductions, and KSVT entries for SDS and Fusarium root rot resistance using three high-throughput methods. (2) Examine the effect of seed treatment fungicides on F. virguiliforme colonization of seedlings and colonization by other pathogenic Fusarium spp. (3) Determine pathogenic variability of Fusarium virguiliforme isolates from multiple Kansas fields.

Project Objectives

Project Deliverables

Progress of Work

Updated August 16, 2019:
2019-20 1st QUARTER REPORT

Sudden death syndrome (Fusarium virguiliforme) is an important disease that affects soybean yields across the United States every year. The pathogen survives in the soil where it starts infection on soybean roots as root rot. After root colonization, F.v. produces a toxin that spreads throughout the plant that kills the vascular system, which in turn, cuts off the plants water supply. Because SDS impacts soybean yields it is important to understand how the disease is spread to understand how to control it. Natural resistance to both the toxin and root phases of the pathogen differs among varieties of soybeans.

OBJ 1. Screen adapted Kansas germplasm and KSVT entries for SDS resistance using three high-throughput methods.

This objective is continued from the 2018-2019 project and overlaps with the final report for last year’s project. This objective is continued from the 2017-2018 project and overlaps with the final report for last year’s project. Germplasm is being screened using three methods: (i) culture extract/toxin assay method, (ii) rolled-towel method, and (iii) layer-cake method. Additionally, a subset of 20 lines from Dr. Schapaugh’s program, which have undergone cut-stem assay screening, rolled towel, and layer cake screening are being screened in the field (Rossville, Kansas) for SDS reaction. See attached PDF.

OBJ 2. Examine the effect of seed treatment fungicides on F. virguiliforme colonization of seedlings and colonization by other pathogenic Fusarium spp. Active ingredients including azoxystrobin and fludioxonil are being tested against soybean root-associated Fusarium spp. See attached PDF for an example of fludioxonol sensitivity testing or Fusarium isolates.

OBJ 3. Determine pathogenic variability of F. virguiliforme isolates from multiple Kansas fields. F. virguilforme are being collected from soil, soybean residue, and symptomatic plants throughout the affected soybean production areas of Kansas as possible. See attached PDF. Other root-associated Fusarium spp. will be isolated from asymptomatic and symptomatic plants. Strains will be isolated into pure culture and single-spored for long-term storage. Pathogenicity assays have not yet been been initiated.

View uploaded report PDF file

Updated October 3, 2019:
2019-20 2nd QUARTER REPORT

(NOTE: Most recent field data acquired end of September 2019; Data analysis completed October 2nd, 2019. Report was delayed in order to have the most up-to-date/"real-time" results submitted.)

Sudden death syndrome (Fusarium virguiliforme) is an important disease that affects soybean yields across the United States every year. The pathogen survives in the soil where it starts infection on soybean roots as root rot. After root colonization, F.v. produces a toxin that spreads throughout the plant that kills the vascular system, which in turn, cuts off the plants water supply. Because SDS impacts soybean yields it is important to understand how the disease is spread to understand how to control it. Natural resistance to both the toxin and root phases of the pathogen differs among varieties of soybeans.

OBJ 1. Screen adapted Kansas germplasm and KSVT entries for SDS resistance using three high-throughput methods.

This objective is continued from the 2018-2019 project and overlaps with the final report for last year’s project. This objective is continued from the 2017-2018 project and overlaps with the final report for last year’s project. Germplasm is being screened using three methods: (i) culture extract/toxin assay method, (ii) rolled-towel method, and (iii) layer-cake method. Additionally, a subset of 20 lines from Dr. Schapaugh’s program, which have undergone cut-stem assay screening, rolled towel, and layer cake screening are being screened in the field (Rossville, Kansas) for SDS reaction.

The toxin assay has been completed for both the Kansas Soybean Variety Trial (KSVT) and the entries from Dr. Schapaugh's program (KS# entries). The rolled-towel assay has been completed for the KSVT and a subset KS# entries. The layer-cake screening is in progress for the KSVT and complete for a subset KS# entries. Examples of the toxin, rolled towel, and layer-cake assays are shown in the attached PDF. The KSVT was not screened in the field for SDS, however a subset of KS# entries have been screened in the field.

An important outcome of this year's project is to relate lab/growth chamber/greenhouse SDS screening data with field disease severity data. Interestingly, there were significant positive correlations between rolled-towel assay disease severity measures and field disease severity data (area under the disease progress curve, AUDPC). Further, seedling parameters including the difference between inoculated and control hypocotyl length, and average and total seedling weight, were positively correlated to field SDS severity. In other words, when disease severity, or the seedling impacts of disease, in the rolled-towel assay is higher, this is associated with higher field severity. These results suggest that the simple ROLLED TOWEL ASSAY HAS THE POTENTIAL TO PREDICT SDS SEVERITY FOR SOYBEAN GENOTYPES. A second year of field data and a repeat of the rolled towel assay for the same set of germplasm will be necessary to confirm this observation.

OBJ 2. Examine the effect of seed treatment fungicides on F. virguiliforme colonization of seedlings and colonization by other pathogenic Fusarium spp.

Active ingredients including azoxystrobin and fludioxonil are being tested against soybean root-associated Fusarium spp. See attached PDF for an example of fludioxonol sensitivity testing or Fusarium isolates. This work is ongoing.

OBJ 3. Determine pathogenic variability of F. virguiliforme isolates from multiple Kansas fields.

F. virguilforme are being collected from soil, soybean residue, and symptomatic plants throughout the affected soybean production areas of Kansas as possible. See attached PDF. Other root-associated Fusarium spp. will be isolated from asymptomatic and symptomatic plants. Strains will be isolated into pure culture and single-spored for long-term storage.

As can be seen from the attached PDF, sample collection locations for strains of F. virguiliforme include Manhattan, Rossville, Silver Lake, Belleville, Scandia, and Columbus, KS.

Pathogenicity assays have not yet been been initiated.

View uploaded report PDF file

Final Project Results

Benefit to Soybean Farmers

Performance Metrics

Project Years