I am an intern at ECHO and made a little summary of research I found on damping off. Hopefully, it can help with the problem solving process!
Problem: Damping Off
Soil Borne Pathogens
Seed Borne Pathogens
Excessive Soil Moisture
Excessive Overhead Misting
Lower soil temperatures before emergence
Higher soil temperatures after emergence
Sources of Pathogens:
–Pathogens can survive for years in soil
Integrated Pest Management (IPM)
- Seed Treatment – “Citrus seed should be treated at 122°F for 10 minutes prior to nursery planting to avoid fungus introduction.” -IFAS bulletin (http://ufdc.ufl.edu/IR00004644/00001)
- Use Resistant Cultivars – Not necessarily available. If a network member were to undertake a citrus breeding program, this would be a helpful quality to select.
- Best Cropping Practices – i.e. higher fertility–>less damping off, many soil conditions affect the rate of damping off,
- Treatment with products – Chemical (products should be rotated to avoid resistant strains of pathogens and used sparingly because of health concern), Biocontrols
Mechanisms of Biocontrols
Antibiosis - microorganism produces antibiotic toxic to pathogen
Parasitism - organism parasitizes the pathogen
Competition for nutrients - organisms use up available nutrients, suppressing pathogen population growth
Production of lyctic enzymes or other chemical signals - microorganism produces metabolites that inhibit pathogen growth
Induced Systemic Resistance (ISR) - microorganism stimulates plants immune system.
Source for above information unless stated otherwise:
*Mechanisms of Biocontrols are taken directly from Table 4
Potential Natural Treatments:
Decrease watering, allow wet-dry cycles in soil
Avoid water run-off from other sources in nursery area
Test irrigation water as a source of pathogens
Clean greenhouse area and tools to avoid spread of pathogens
Sterilize soil before planting with solarization or steaming
Sterilize seeds before planting
Increase fertility of soil before planting
Use biocontrols, either commercially produced or Actively Aerated Compost Teas (https://www.finegardening.com/article/brewing-compost-tea) / Indigenous Microorganisms as a soil drench and foliar spray. A commercially produced biocontrol will specifically target your disease, while Actively Aerated Compost Tea has a good chance of using one of the 5 mechanisms of biocontrols to prevent damping off.
Additionally, if seedlings get cold, damping off is more likely to occur. Keep them warm!
If any of these work or do not work, please let us know.