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. 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.
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. 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.
Biological control strategies have not been developed for damping-off and seedling blights of lentil.
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 controls are most effective when integrated with sound cultural practices.
Product List for Root Rot and Seedling Blight of Lentil:
Pesticide |
Product per 100 pounds seed |
Remarks |
Azoxystrobin |
|
|
|
Protégé |
0.153-0.763 fl oz |
Broad spectrum suppression of seed decay and damping-off pathogens |
Captan |
|
|
|
Captan 30-DD |
2 fl.oz |
Broad spectrum suppression of seed decay and damping-off pathogens |
|
Captan 400 |
2.5 fl.oz |
Broad spectrum suppression of seed decay and damping-off pathogens |
Fludioxinil |
|
|
|
Maxim |
0.08-0.16 fl oz |
Suppression of Rhizoctonia and Fusarium spp. |
Mefenoxam/Metalaxyl |
||
|
Allegiance |
0.10 – 0.375 fl.oz |
Suppression of Pythium sp. |
|
Apron FL |
0.75–1.5 lb/100 fl.oz |
Suppression of Pythium sp. |
|
Apron XL LS |
0.32 – 0.64 fl.oz |
Suppression of Pythium sp. |
|
Apron 50W |
0.5 – 1.0 oz |
Suppression of Pythium sp. |
|
Thiram |
|
|
|
Thiram |
3 oz |
Broad spectrum suppression of seed decay and damping-off pathogens |
In Furrow Treatments |
||
Azoxystrobin |
|
|
|
Amistar |
0.125-0.25 oz/1000 feet |
In furrow treatment for Rhizoctonia suppression |
|
Quadris |
0.4-0.8 fl oz/1000 feet |
In furrow treatment for Rhizoctonia suppression |
Mefenoxam |
|
|
|
Ridomil Gold EC |
½ -1 pt per acre in a 7” band |
Suppression of Pythium sp.; Incorporate mechanically or by irrigation |
Categories: Pulse Crops, Disease, Root Rot, Seedling Blight, Lentil
Date: 04/02/2007