HPIPM:Bacterial Stalk Rot

Taxonomy

Domain	Bacteria
Phylum	Proteobacteria
Class	Gammaproteobacteria
Order	Enterobacteriales
Family	Enterobacteriaceae
Genus	Dickeya

Scientific Name

Dickeya chrysanthemi

Scientific Name Synonyms

Erwinia carotovora var. chrysanthemi

Erwinia chrysanthemi Pineapple Strain

Pectobacterium carotovorum var. chrysanthemi

Erwinia chrysanthemi

Pectobacterium chrysanthemi

Common Name

bacteria wilt and soft rot

Author: Howard F. Schwartz and David H. Gent

Identification and Life Cycle

Bacterial stalk rot is caused by the bacteria Erwinia carotovora subsp. carotovora and E. carotovora subsp. atroseptica. Bacterial stalk rot is primarily a disease of stressed or senescing plants, and infection generally occurs late in the season after extended wet periods. Infections occur in areas where water collects, such as leaf petiole axils, and is aided by wounds created by insect feeding (i.e., sunflower budworm), other pathogens such as Alternaria leaf spot, or mechanical injury. The bacterial stalk rot pathogens are readily disseminated in and among sunflower fields by splashing rain and irrigation water, as aerosols, and surface irrigation waters. The pathogens survive between sunflower crops in infected crop debris and as pathogens on many other plants, including potato, onion, and carrot.

Plant Response and Damage

Bacterial stalk rot symptoms first appear as a blackening of stems, often centered around a leaf petiole axil. The pith of infected stems is black and watery, and the rot eventually hollows stems. Plants often lodge as stems rot. Heads can be infected occasionally, causing a soft, watery rot that discolors seeds and flowers. The disease can reduce yield and seed quality, but is of little economic concern in the High Plains.

Biological Control

No biological control strategies have been developed for bacterial stalk rot.

Cultural Control

Avoid rotations with susceptible crops such as potato and other vegetables. Do not reuse irrigation tail water from vegetable crops if sunflowers are irrigated. Practice strict sanitation of weeds, volunteer sunflower, and crop debris to reduce pathogen survival between sunflower crops.

Chemical Control

No chemical controls are effective against bacterial stalk rot.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.