Damping-off is a disease of seeds (pre-emergence damping-off) and seedlings (post-emergence damping-off or seedling blight) that can be caused by many fungi, primarily Pythium spp., Phytophthora spp., Fusarium spp., Rhizoctonia spp., and perhaps others. These fungi are common inhabitants in soils worldwide and have a broad host range. They survive between crops as dormant resting structures (oospores, sclerotia), in crop debris, saprophytically, and pathogenically on weeds and other hosts.
Pre-emergence damping-off results in seed rot and seedlings that never emerge. Initial root rot symptoms appear as elongated water-soaked areas on roots one to three weeks after planting. The pathogen will extensively prune roots, reduce overall plant growth, and can destroy much of the main root system. The water-soaked region may extend several inches above the soil line, with little, if any, visible evidence of the fungus. The water-soaked area eventually dries out, becomes somewhat sunken, and tan to brown in color. Aboveground symptoms include stunting and yellowing; eventually plants wilt and die. Damage usually is most common when seed quality is poor and/or seed has been damaged by freezing, herbicides, or the presence of other pathogens. Slow germination and poor drainage typically result in damping off and seedling blight.
T-22 Planter Box (Trichoderma harzianum strain KRL-AG2) is registered as a seed treatment for damping off diseases. Do not use in alkaline soils or if soil is below 50oF.
Deny (Burkholderia cepacia) is registered for protection of roots from Fusarium, Rhizoctonia, and Pythium spp., but its efficacy in the High Plains is unknown.
Kodiak is registered for protection of roots from Fusarium spp and Pythium spp.
Plant high quality seed into well-prepared seedbeds under conditions that promote rapid seed germination and seedling emergence. Avoid compaction, poor drainage, herbicide injury, and other stresses that delay germination and thus increase the chance for seed and seedling infection. Very little or no information is available on resistant varieties. Crop rotation may provide some control of some of the pathogens involved in the damping-off complex, but will not suppress pathogens such as Pythium spp. that have very broad host ranges. Increased seeding rates will partially compensate for seedlings that are killed.
Treat seed with a broad-spectrum fungicide to suppress damping off pathogens. Seed treatments provide early-season suppression of damping off fungi, but often lose their effectiveness as plant roots grow.
Product List for Damping-Off and Seedling Blight:
Pesticide |
Rate per 100 lb seed |
Application Frequency (days) |
Remarks |
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Captan |
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Captan 75 |
6-9 oz |
Seed treatment |
Broad spectrum, but weak against Pythium and Phytophthora spp. |
|
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Captan 30-DD |
1.25 fl oz |
Seed treatment |
Broad spectrum, but weak against Pythium and Phytophthora spp. |
|
|
Captan 400 |
1-2 fl oz |
Seed treatment |
Broad spectrum, but weak against Pythium and Phytophthora spp. |
|
|
Captan 400-C |
1-2 fl oz |
Seed treatment |
Broad spectrum, but weak against Pythium and Phytophthora spp. |
|
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Fludioxonil |
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Maxim 4FS |
0.08-0.16 fl oz |
Seed treatment |
Suppression of Fusarium and Rhizoctonia spp. |
|
|
Metalaxyl/Methoxonam |
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Allegiance FL |
1.5-3.0 fl oz |
Seed treatment |
Suppression of Pythium and Phytophthora spp. |
|
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Allegiance LS |
2.4-4.9 fl oz |
Seed treatment |
Suppression of Pythium and Phytophthora spp. |
|
|
Apron XL LS |
1.28 fl oz |
Seed treatment |
Suppression of Pythium and Phytophthora spp. |
|
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Thiram |
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42-S Thiram |
8 fl oz |
Seed treatment |
Broad spectrum |
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Thiram 50WP |
8 oz |
Seed treatment |
Broad spectrum |
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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: Canola, Mustard, Disease, Damping Off, Seedling Blight
Date: 12/30/2004