How to Kill Fungi on Wood in a Terrarium

Open the lid of your closed terrarium to increase air circulation and allow some of the water inside to evaporate. Fungi thrive in moist conditions and excess moisture is often at the root of terrarium fungus problems.

Move the terrarium to a sunny location, as long as the plants inside can adjust to full sun without harm. Fungi thrive in dark locations and moving the terrarium out of the shade can reduce fungal growth.

Remove the affected wood from the terrarium. Scrape visible fungi off the surface of the wood with a drywall finishing knife or a similar sturdy, flat scraper. Dispose of fungi in a trash bag; seal it and throw it away. Disinfect the scraper in a mixture of 1 part household bleach and 9 parts water. Wash the wood outside with a garden hose to remove any fungus residue. Leave the wood in a warm, dry area until the surface is dry to the touch. The wood must be dry before treatment because borate wood preservatives are water soluble and do not work on wet surfaces.

Dust a powdered borate, such as one containing the active ingredient disodium octaborate tetrahydrate, generously onto the wood at a rate of 1 teaspoon per square inch of wood. Wait 24 hours for the borate wood preservative to set. Return the treated wood to the terrarium. Borate wood preservatives are effective in killing and preventing fungal growth on wood. Alternatively, mix 1 part powdered borate with 9 parts water in a 5-gallon bucket to create a 10-percent borate solution. Brush the solution generously onto the wood with a paintbrush or clean sponge at a rate of approximately 1 teaspoon per 7.5 square inches or until the wood is saturated. Wait for the wood to dry. Repeat once for a total of two applications. Wait for the wood to dry. Return the wood to the terrarium.