HPIPM:Fusarium Yellows Sugarbeets

Taxonomy

Domain	Eukarya
Kingdom	Fungi
Phylum	Ascomycota
Subphylum	Pezizomycotina
Class	Sordariomycetes
Subclass	Hypocreomycetidae
Order	Hypocreales
Family	Nectriaceae
Genus	Fusarium

Scientific Name

Fusarium oxysporum

Common Name

Fusarium root rot and wilt

Author: Howard F. Schwartz, David H. Gent, Robert Harveson, Barry Jacobsen, and Martha Mikkelson

Identification and Life Cycle

Fusarium yellows is caused by the fungus Fusarium oxysporum f. sp. betae. The pathogen infects sugarbeets through roots and grows into water conductive tissues (vascular tissue), releasing toxins that causing wilting and yellowing symptoms. Disease symptoms are most pronounced during high temperatures and usually do not occur before July in the High Plains region. The fungus is spread primarily in contaminated soil. Fusarium oxysporum can survive between sugarbeet crops in soil and crop debris as dormant chlamydospores. F. oxysporum strains pathogenic to sugarbeets may also be pathogenic on other hosts, including dry bean.

Plant Response and Damage

Disease symptoms initially appear as yellowing (chlorosis) between veins on older leaves; younger leaves later become chlorotic. Often only one side of a leaf is affected. Leaves eventually become dry and brittle as the disease progresses. When beets are cut open, the internal vascular tissue appears grayish brown and discolored. Yield losses can be significant when large populations of the pathogen build up in soils.

Biological Control

No biological control strategies have been developed for Fusarium yellows.

Cultural Control

Plant varieties less susceptible or resistant to Fusarium yellows. Long crop rotations with non-hosts (i.e., small grains, corn, alfalfa) provide some control, but are not always effective because the fungus can survive on several alternate hosts. Reduce plant stress caused by compaction, moisture extremes, and other sub-optimal soil conditions.

Chemical Control

No chemical controls are available for Fusarium yellows.

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.