Damping off and root rot of spinach
May 7, 2019 8:32 AM
Fungal causal agents: Fusarium and Rhizoctonia sp./spp.
Symptoms: Symptoms of damping off and root rot consist of poor seed germination, preemergence death of seedlings, postemergence death of newly emerged seedlings, stunted plants, yellowed lower leaves, general poor growth, wilting, and eventual collapse and death of older plants. Roots of infected plants can appear water-soaked or brown to black in color. The upper taproot may be girdled by a necrotic lesion, or the tip of the taproot may be necrotic. In severe cases, nearly all roots may be girdled or rotted off. Damping-off is problematic in spinach production areas throughout the world. Severity is influenced by cultivar, soil texture, irrigation, and pathogen populations. Severe damping-off is associated with clay or poorly draining soils with a history of frequent spinach production. While all stages of spinach can be infected by root rot organisms, newly emerging plants and young seedlings are very susceptible.
Symptomatic plants can be associated with low areas in the field and places where water is slow to drain away. These spinach problems are caused by a complex of pathogenic soil fungi that include one or more of the following: Fusarium oxysporum, Pythium (several species), and Rhizoctonia solani. These fungi are soil inhabitants and are therefore permanent residents in infested soils. However, aboveground symptoms of plants that are overwatered are similar to symptoms of root rot. Excess water can damage roots, causing tan to brown, water soaked symptoms on roots even if no pathogen is present.
Management:. Plant spinach in well draining soils. Prepare seed beds so that even, rapid germination is enhanced. Carefully manage the irrigation schedule to prevent flooding and saturated soil conditions. Plant seed that is treated with fungicides and fumigate the beds. Preplant application of mefenoxam will only control damping-off caused by Pythium. Avoid planting consecutive spinach crops and practice good crop rotation. Check CDMS or Agrian for currently labeled fungicides.