Many pathogens can cause damping off and seedling blight of sugarbeet in the High Plains region, including Pythium spp., Rhizoctonia solani, Phoma betae, Aphanomyces cochlioides, and perhaps others. Damping off is associated with cool to warm soil temperatures, excess soil moisture, and delayed seedling emergence. Pathogens associated with damping off are common soil inhabitants and can survive in soil as dormant oospores or sclerotia, pathogenically on alternate hosts and weeds, and saphrophytically on crop residues.
Damping off can occur before or after crop 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 also form on hypocotyls and roots after emergence when infected with Pythium spp., causing plants to collapse and wither. Post-emergence damping off caused by R. solani begins as elliptically shaped, brown to black sunken cankers on roots and hypocotyls with a sharp margin between infected and healthy tissue. Plants can become flaccid and die, but lightly infected roots often survive and produce nearly normal roots.
Phoma seedling infection appears as brown to black discoloration of the hypocotyl and stunting of plants. Seedlings can be killed, but may survive and recover as plants develop.
Deny (Burkholderia cepacia) and T-22 (Trichoderma harzianum strain KRL-AG2) are registered for use on sugarbeet, but their efficacy in the High Plains is unknown.
Plant high quality seed in warm, well-prepared seedbeds under conditions favorable to rapid seedling emergence; shallow planting can encourage rapid emergence. Avoid excess irrigation and poor drainage. Crop rotation with non-hosts (i.e., small grains) may provide some reduction in damping off pathogens, but some damping off and seedling blights pathogens have very broad host ranges and can attack most plants.
Seed treatment with broad-spectrum fungicides is an economical and effective means of reducing disease, but often a combination of two or more fungicides is required to control the spectrum of damping-off and seedling blight pathogens.
Product List for Damping-Off and Seedling Blight:
Pesticide |
Rate per 100 lb seed |
Application Frequency (days) |
Remarks |
|
Azoxystrobin |
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Amistar |
0.125-0.25 oz |
In furrow or directed spray after cultivation |
Suppression of Rhizoctonia spp. |
|
Quadris |
0.4-0.8 fl oz |
In furrow at planting |
Suppression of Rhizoctonia spp. |
|
Captan |
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Captan 30-DD |
4.75-9.5 fl oz |
Seed treatment |
Broad spectrum , but weak against Pythium spp. |
|
Captan 400 |
6-12 fl oz |
Seed treatment |
Broad spectrum , but weak against Pythium spp. |
|
Captan 400-C |
6-12 fl oz |
Seed treatment |
Broad spectrum , but weak against Pythium spp. |
|
Fludioxonil |
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|
Maxim 4FS |
0.08-0.16 fl oz |
Seed treatment |
Suppression of Fusarium and Rhizoctonia spp. |
|
Hymexazol |
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|
Tachigaren 70WP |
1.0-2.0 oz |
Seed treatment |
Suppression of Aphanomyces, Pythium spp. |
|
Metalaxyl/Methoxonam |
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|
Apron XL LS |
0.085-0.64 fl oz |
Seed treatment |
Suppression of Pythium and Phytophthora spp. |
|
Allegiance-FL |
0.75 fl oz |
Seed treatment |
Suppression of Pythium and Phytophthora spp. |
|
Allegiance-LS |
1.2 fl oz |
Seed treatment |
Suppression of Pythium and Phytophthora spp. |
|
Ridomil Gold EC |
1-2 pt |
Pre-plant incorporated soil drench or soil band (a 7” band is recommended) |
Suppression of Pythium and Phytophthora spp. |
|
Ridomil Gold GR |
20-40 lb |
Pre-plant incorporated soil drench or soil band (a 7” band is recommended) |
Suppression of Pythium and Phytophthora spp. |
|
Ultra Flourish |
2-4 pt |
Pre-plant incorporated drench or 7” soil band |
Suppression of Pythium and Phytophthora spp. |
|
Thiram |
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|
42-S Thiram |
8 fl oz |
Seed treatment |
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Thiram 50WP |
8 oz |
Seed treatment |
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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. |
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Categories: Sugarbeet, Diseases, Damping-Off, Seedling Blight
Date: 03/27/2005