P-153 - Evaluation of Tobacco Variety Resistance to Phytophthora nicotianae Races in Major Tobacco-Growing Regions of the U.S.

Monday, August 4, 2025

3:45 PM - 4:30 PM HST

Location: Exhibit Hall 3

Author(s)

DA

Daisy Ahumada, n/a

Assistant Professor
North Carolonia State University
Raleigh, North Carolina, United States
CF

Colin Fisher

Univerity of Kentucky
Lexington, Kentucky, United States
MR

Mitchell Richmond

University of Tennessee
Knoxville, Tennessee, United States
JM

J. Michael Moore, PhD

Professor and Extension Agronomist
University of Georgia
Tifton, Georgia, United States
KC

Kamal Chhetri, PhD student

Virginia Tech
Blacksburg, VA, USA
TR

Thomas D. Reed

Southern Piedmont Agricultural Research and Extension Center, Virginia Tech, Blackstone, VA 23824 / School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA 24061
Blackstone, Virginia, United States

Presenting Author(s)

YZ

Yuan Zeng

Assistant Professor
Southern Piedmont Agricultural Research and Extension Center, Virginia Tech, Blackstone, VA 23824 / School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA 24061
Blackstone, Virginia, United States

Abstract Text: Phytophthora nicotianae is a soilborne oomycete pathogen causing black shank in tobacco. Four races (0, 1, 2, and 3) of the pathogen have been identified, with races 0 and 1 being more prevalent in the U.S. Host resistance is the most effective strategy to manage black shank but reports of increasing losses in previously resistant varieties from some tobacco-producing countries suggest potential shifts in races. In 2023 and 2024, as part of CORESTA’s Black Shank Collaborative Study, seven field experiments were conducted in naturally P. nicotianae-infested soils in Kentucky, North Carolina, Tennessee, and Virginia to assess known sources of resistance. Thirteen tobacco varieties with different resistant mechanisms were evaluated. ‘Beinhart 1000-1’ and ‘KT 215’ demonstrated high resistance to races 0 and 1, with survival rates exceeding 80% across locations. In contrast, ‘KY 14’, ‘Hicks’, and ‘KY 907’, which are highly susceptible to both races, and ‘KY14xL8’ and ‘NC 1071’, which are immune to race 0 but not race 1 had a nearly total loss at multiple sites, indicating that race 1 was predominant at all the test sites. Other varieties showed variable disease severity, likely influenced by environmental factors such as soil temperature, soil moisture, and pathogen inoculum. However, ‘K326 Wz’, resistant to both races, maintained over 70% survival in Virginia, North Carolina, and Tennessee but had significantly lower survival in Kentucky in both years, suggesting the presence of a more aggressive P. nicotianae isolate in Kentucky capable of overcoming the Wz resistance gene.