Cotton (Southeast)
Coordinated by Heather M. Kelly (youngkelly@utk.edu), Assistant Professor, Extension and Research Field Crops Plant Pathologist, The University of Tennessee, Entomology and Plant Pathology Department

Background

Cotton acreage in the southeast and midsouth, which totaled 3.2 million, made up for approximately 45% of total U.S. cotton yield in 2015 and is projected to increase in the future. Target spot, caused by the fungus Corynespora cassiicola, is an emerging disease in cotton and an established disease in soybean, sesame, tomato, cucumber, and container-grown ornamental crops. Very little is known about the source, spread, and survival of C. cassiicola in cotton. Target spot on cotton has increased in its range from the initial reports in southwest Georgia to Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Virginia.

Cotton
Cotton (Gossypium hirsutum L.), 
John C. French Sr., Retired, Universities:
Auburn, GA, Clemson and U of MO,
 Bugwood.org

Objective

This program aims at providing information that will fill in the knowledge gaps about target spot and possible impacts of production practices (i.e. tillage, plant population, plant date, variety, previous crop, irrigation, soil type) on disease development and disease onset. Bridging these gaps will build the foundation for developing more stable IPM strategies for target spot in cotton. Other cotton disease information reported will also help identify problematic diseases in cotton and based on agronomic information alert stakeholders to other disease epidemics occurring that season. Furthermore, the distribution of pest identification and risk information will improve general disease identification and knowledge about IPM strategies in cotton concerning foliar disease control for cotton producers.

Situation

Many states have first reported target spot on cotton only in the past 3 years. While no varieties have displayed complete resistance to the disease, yield losses have ranged from 5% up to 20% across different varieties evaluated in 2012 and 2013 under ideal conditions for target spot development in Alabama. In Georgia, disease-related yield loss estimates from 200 to 600 lb lint/A ($180 to $540/A at previous world cash price). Presently, more information about target spot distribution across eastern U.S. cotton 

production area and about disease onset  in the season is needed to better understand the epidemiology and potential impact on yield. IPM options are restricted due to limited information on the disease development and fungicide efficacy.

Important Pests

Target Spot (Corynespora cassiicola).

Corynespora leaf spot
Target spot (Corynespora cassiicola) (Bark & M.A. Curtis),
Jason Brook, University of Georgia, Bugwood.org

UTIA Icon