Fungal Problems

Fungi spores are omnipresent, which means they are everywhere in the atmosphere under normal conditions. Fungi tend to opportunistic, attacking plants that have been compromised by some other means first. An open sore or cut is usually the first problem, which can later lead to fungal attacks. Keeping your plants clean and healthy is the first line of defense in preventing fungal problems.

Symptom/Detail Link/Cause Description/Solution
Leaves or pseudobulbs have brown or black irregular spots. Fungal rot
This type of infection usually indicates that the plant has been weakened already. Misting with cold water, or exposure to a draught are common causes. Remove the affected areas with a clean sharp and sterile knife, cutting 1/4-inch into healthy tissue. Dousing with hydrogen peroxide can also disinfect affected areas if they are small and/or numerous. Any cut areas should be treated with fungicide to help the wound to seal up properly. Keep the plant in a warmer area and reduce watering somewhat until recovery is complete.
Pseudobulbs have brown or black "bruises". Rhizome rot
Cattleya family plants are particularly prone to this problem, usually during colder months of the year. The problem begins with darkening in the rhizome area and crawls up the pseudobulbs from the base. If untreated, this problem progresses quickly, and can kill your plant in a matter of days. Remove the affected pseudobulbs and rhizome areas with a clean sharp knife, cutting 1/4-inch into healthy tissue. Any cut areas should be treated with fungicide to help the wound to seal up properly. Keep the plant in a warmer area and reduce watering somewhat until recovery is complete.
Younger leaves became mushy or translucent, and then turned black. Crown rot
Typically this happens on plants where the young leaves form a cup, such as in phalaenopsis. Any water accumulating in this area will usually lead to this problem. Try to carefully remove the affected areas and treat with fungicide to prevent the area from spreading. Growth will not resume from this point, so you will have to wait for a side growth or keiki to develop. In future, ensure your plants are completely dry by evening. Avoid misting plants directly, and only mist around the plant to increase humidity in future.
Stems or leaves have developed blackened areas. Cold damage This tends to occur only during the winter months, when plant parts come into contact with a cold window pane. Relocate the plant to a warmer area during the winter months, and refer to the information above if the area starts to spread.
Flower spotting Botrytis fungus
This problem is more common during the cooler months of the year, and is much more obvious on lighter colored or white flowers. The Botrytis fungus prospers at cooler temperatures coupled with high humidity. Keep your growing area clean, and destroy any affected flowers to address this problem. Also raising the temperature a bit will help prevent the problem from recurring.
Fungal treatments Fungal attacks There are a number of commercial fungal treatments on the market, such as Funginex, Damp-off, etc. If you prefer a safe home solution, then one of the following treatments may suit your needs :
  1. Hydrogen Peroxide - available as 3% solution from pharmacies - use full strength to disinfect areas affected by things like crown rot. No need to rinse, as it degrades to oxygen and water on contact with contaminants.
  2. Sulphur powder - available from most pharmacies as "flowers of sulphur" - use directly to seal any open cuts or wounds, it acts like a bandage.
  3. Cinnamon powder - available from your spice rack - use directly to seal any open cuts or wounds, it also acts like a bandage but smells better than sulphur powder.
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