Many pathogens can cause damping-off of sorghum seedlings in the High Plains region, including Pythium spp., Fusarium spp., Phoma spp., Aspergillus spp., and Rhizoctonia spp. Pythium spp. appear to be the most important. Damping-off is associated with cool, wet soils. Damping-off pathogens are common soil inhabitants and can survive in soil and crop residues as dormant oospores or sclerotia, pathogenically on alternate hosts and weeds, and saphrophytically on crop residues.
Damping-off can occur before or after sorghum 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. Red, brown, or black lesions may also form along roots and at the root tip, halting root developing. Water-soaked, greasy lesions may also form on stem and roots after emergence when infected with Pythium spp., causing plants to collapse and wither.
No biological control strategies have been developed for sorghum damping-off and seedling blights.
Plant high quality seed in well-prepared, warm soils that encourage rapid emergence. Damaged, weathered, or moldy seed germinate poorly and are more prone to damping-off and seedling blights. Avoid compaction, poor drainage, herbicide injury, and other factors that delay seedling emergence and dispose plants to disease. Varieties differ in their vigor and tolerance to damping-off and seedling blights. Hybrids tend to be most tolerant to damping-off and seedling blights and should be planted where available.
Treat seed with broad-spectrum systemic and contact fungicides.
Product List for Damping-Off and Seedling Blight:
|
Pesticide |
Rate per 100 lb seed |
Remarks |
|
Captan |
||
|
Agrox 3-way |
5.3 oz |
Broad spectrum, but does not suppress Pythium spp. |
|
Arasan 70S |
2.5 oz |
Broad spectrum, but does not suppress Pythium spp. |
|
Captan 30DD |
3.5 fl oz |
Broad spectrum, but does not suppress Pythium spp. |
|
Captan 400 |
1.75-4.5 fl oz |
Broad spectrum, but does not suppress Pythium spp. |
|
Captan 400-C |
1.75-4.5 fl oz |
Broad spectrum, but does not suppress Pythium spp. |
|
EBDC |
||
|
Dithane F45 |
4.3-7.2 fl oz |
Broad spectrum, but weak against Pythium spp. |
|
Dithane M45 |
2.7-4.5 oz |
Broad spectrum, but weak against Pythium spp. |
|
Manzate 75 DF |
2.7-4.5 oz |
Broad spectrum, but weak against Pythium spp. |
|
Manzate 80 WP |
2.7-4.5 oz |
Broad spectrum, but weak against Pythium spp. |
|
Manzate Flowable |
4.3-7.2 fl oz |
Broad spectrum, but weak against Pythium spp. |
|
Fludioxinil |
||
|
Maxim 4FS |
0.08 - 0.16 fl oz |
Broad spectrum |
|
Metalaxyl/Mefenoxam |
||
|
Allegiance FL |
0.375-0.75 fl oz |
Suppression of Pythium spp |
|
Allegiance LS |
0.66-1.2 fl oz |
Suppression of Pythium spp |
|
Apron 25, 2E |
2 oz |
Suppression of Pythium spp |
|
PCNB |
||
|
Terra Flo 25 |
2.2 fl oz |
|
|
Terra-Coat SD205 |
2 oz |
|
|
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. |
|||
Categories: Sorghum, Diseases, Damping-Off, Seedling Blight
Date: 03/28/2005