Studies on red crown rot of soybean: incidence in Illinois, fungicide seed treatments, and host resistance

Welker, Whitney L

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https://hdl.handle.net/2142/115826 Copy

Description

Title

Studies on red crown rot of soybean: incidence in Illinois, fungicide seed treatments, and host resistance

Author(s)

Welker, Whitney L

Issue Date

2022-04-28

Director of Research (if dissertation) or Advisor (if thesis)

• Hartman, Glen L
• Diers, Brian

Department of Study

Crop Sciences

Discipline

Crop Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• soybean
• soybean disease
• red crown rot
• Calonectria ilicicola
• RCR
• CBR
• fungus
• peanuts

Abstract

Soybean [Glycine max (L.) Merr.] is an economically important crop in Illinois, and also globally. In 2021, there was an estimated 4.28 million hectares of soybeans planted in the state of Illinois. Calonectria ilicicola Boedijn & Reiltsma is a soilborne fungus that causes red crown rot (RCR) of soybean. The pathogen was originally described causing a disease in peanuts, called Cylindrocladium black rot, in Georgia in 1965. RCR was first reported on soybean in the United States in 1972. This fungus that causes RCR also causes pre- and post-emergence damping off in soybean as well as root rot and foliar chlorosis and necrosis after flowering. Infected plants die prematurely reducing seed production. There were 14 confirmed counties with RCR in Illinois including Bureau, Christian, Effingham, Fayette, Ford, Kankakee, Livingston, Madison, Marion, Pike, Tazewell, Sangamon, St. Clair, and Woodford based on 2020 and 2021 field surveys in southern and western Illinois and based on the University of Illinois Plant Clinic data of positive samples of RCR from 2018 to 2021. Based on locations of these 14 counties, RCR encompasses a wider distribution in Illinois than just the southern or western part of the state. Literature indicates that rotation between grain crops (non-legume), avoiding or reducing wet areas in the field, and tillage might be effective for RCR management. Soybean fungicide seed treatment labels do not include RCR, which led to several experiments to determine if fungicides are effective in controlling seed rot, pre- and post-emergence damping off caused by C. ilicicola. Overall, CruiserMaxx® Vibrance® + Saltro® provided the best treatment results that were equal to the non-inoculated control for stand counts, root rot ratings, and plant weights. Another approach that has not been well explored for the potential management of red crown rot is the use of host plant resistance. There is very little information about screening soybeans to identify sources of resistance to this pathogen, C. ilicicola, and to date, no cultivars have been developed with resistance to RCR. Three experiments were completed, one for breeding lines/cultivars and two for soybean ancestral lines. For the breeding lines/cultivar experiment, LD10-10219 had the lowest root rot rating. In the first ancestral experiment, which included older modern cultivars among the ancestors, Corsoy 79 and Williams 82 generally had the lowest root rot ratings. In the second ancestral experiment, Mukden, Tokyo, PI 54610, and Dunfield had the lowest root rot ratings. The significant differences among genotypes observed in these evaluations show that some genotypes may carry genes for resistance to C. ilicicola.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

N/A

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