Epidemiology of Phomopsis Seed Decay of Soybeans: Infection Progress and the Effects of Weather and Host Resistance
Shortt, Barry James
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/70583
Description
Title
Epidemiology of Phomopsis Seed Decay of Soybeans: Infection Progress and the Effects of Weather and Host Resistance
Author(s)
Shortt, Barry James
Issue Date
1982
Department of Study
Plant Pathology
Discipline
Plant Pathology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Plant Pathology
Abstract
Phomopsis seed decay of soybeans (Glycine max L.), caused by the fungi Diaporthe phaseolorum (Cke. & Ell.) Sacc. var. sojae Wehm. and an unidentified Phomopsis sp., reduces the germination, vigor, and quality of seeds grown in seasons with warm, wet weather near harvest. The establishment of Phomopsis sp. in six soybean cultivars was measured in natural field epidemics in east-central Illinois in 1980 and 1981. Infection incidences in surface disinfested plant parts were estimated by recovery of the pathogen on potato-dextrose agar. Infection progress curves for the period between emergence and harvest were analyzed using the Weibull cumulative distribution function, and were related to weather using multiple linear regression.
Plant infection increased faster, and seed decay was greater in 1981 than in 1980, primarily because of wetter weather. Shapes of the infection progress curves differed between years, and to a lesser extent, between plant parts. The incidences of infected stem pieces, pod halves, and seeds were not closely related, although all were greater in 1981. Seed decay was low in 1980, but in 1981 ranged from 0.5% in Elf to 26% in Wells. Resistance to seed decay, also expressed as low seed infection, apparently did not involve resistance to stem or pod infection. Stem and pod infection were affected by rainfall, dew, and humidity. Seed infection was affected by host resistance, stage of development, and humidity and temperature. Seed decay was greatest in the maturity group II cultivars, but an infection assay of pods and seeds in vitro detected little difference between maturity groups.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
