HPIPM:Root Rot and Seedling Blight of Lentil

Taxonomy

Domain	Eukarya
Kingdom	Fungi
Phylum	Basidiomycota
Subphylum	Agaricomycotina
Class	Agaricomycetes
Order	Cantharellales
Family	Ceratobasidiaceae

Scientific Name

Rhizoctonia

Common Name

root rot/damping off

Root Rot and Seedling Blight of Lentil (Scientific name )

Author: Howard F. Schwartz, David H. Gent, Martha Mikkelson, and Jack Riesselman

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Cause

Various root rot pathogens attack lentil in the High Plains, including Pythium spp., Fusarium spp., and Rhizoctonia spp. These pathogens are widespread in soils throughout the High Plains, but generally cause little damage to lentil.

Symptoms

Damping-off can occur before or after lentil emergence. Pre-emergence damping-off results in a brown, gelatinous rotting within the seed coat. Radicles and cotyledons may become brown and soft after germination, but fail to emerge. Water-soaked, greasy lesions may form at the soil line and on roots after emergence when infected with Pythium spp. causing plants to collapse and wither. Patches of seedlings can be girdled and killed.

Impact of Disease

Root rot and seedling blights often make it difficult to establish uniform plant stands in the Northern High Plains if proper control strategies are not practiced.

Life Cycle of the Pathogen

Damping-off is associated with soil conditions unfavorable for seed germination and emergence, such as cool soil temperatures and excessive soil moisture. Pathogens associated with damping-off are common soil inhabitants and can survive in soil as dormant resting structures, pathogenically on alternate hosts and weeds, and saphrophytically on crop residues.

Management Approaches

Biological Control

Serenade Soil is registered for root rot control, but its efficacy in the High Plains is unknown.

Cultural Management Practices

Plant high quality seed in a firm, well-prepared seedbed at optimum pH, soil temperature (at least 50ºF), and fertility level for rapid germination and growth. Apply adequate but not excessive nitrogen fertilization. Avoid compaction, poorly drained fields, herbicide carryover, and excess irrigation that can favor damping-off pathogens. Crop rotation may provide some disease control, but some damping-off fungi such Pythium spp. have broad host ranges and can survive long periods of time as oospore in the absence of a host. Crop rotation of five years or longer crop rotation can reduce some pathogen populations. Tillage and burial of crop debris provides a practical control measure for Rhizoctonia solani.

Chemical Management Program

Chemical controls are most effective when integrated with sound cultural practices.

Consult pesticide labels for additional rate, application, and safety information. Additional information and current labels can be found at http://www.greenbook.net or http://www.cdms.net.

References

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.