ECHOcommunity Conversations

Are there organic/natural treatments for damping-off disease in citrus?

#1

Dear All,
We often have problems with our citrus seedlings in our nursery. They sprout up well, but after that they rot at the soil level. Do you know of organic or natural treatments we can make to prevent this?
I work with Agri-Plus in Haiti. Thank you,

Mike

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#2

Hello Mike,
I’m not exactly an expert (and we live in a much drier environment in East Africa where this is not a problem), but my guess would be disinfecting the nursery, boiling the pots and nursery tools should reduce the pathogens. As for natural remedies, Melia azedarach has a good reputation as a biological fungizide, as has Neem.

Blessings,
Martin

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#3

There is something called yellow dragon which is a fungus which kills citrus. Cuba is just recovering from it. it kills all the citrus by preventing the tree from drawing in water. The solution is to use clones which are resistant to it. You cannot plant citrus where infected plants have been planted. Whole orchards of 1000’s of ha have had to be destroyed (makes good charcoal). There are experts here in Cuba who could probably help you. If you want help I will try to find someone.

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#4

This is a collection of resources on ECHOcommunity which may be helpful to the conversation.

https://www.echocommunity.org/en/resources/8ec68447-e2d7-41c5-aac9-8150a87d514a

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#5

Hi Mike,

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

Causes:
Soil Borne Pathogens
Seed Borne Pathogens

Factors:
Excessive Soil Moisture
Excessive Overhead Misting
Lower soil temperatures before emergence
Higher soil temperatures after emergence

Sources of Pathogens:
Water run-off
-contaminated irrigation
-rain
Unsanitary greenhouses
–Pathogens can survive for years in soil

Management Approaches:
Integrated Pest Management (IPM)

  1. 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)
  2. 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.
  3. Best Cropping Practices – i.e. higher fertility–>less damping off, many soil conditions affect the rate of damping off,
  4. 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:
https://hal.archives-ouvertes.fr/hal-01606538/document
*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.

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#6

yes prevention better than cure! Cure for damping off is difficult, it acts fast. As mentioned, moisture management is crucial - under soil irrigation/leaky pipe prevents soil surface moisture which helps - avoid sprinklers, misters etc. Allow air flow and promote dry soil surface environment. Resistant cultivars help but then there’s no incentive to prevent!

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