Root Awakening: Remove adult fungus gnats with sticky traps

Fungus gnats thrive in moist growing media

Why are there fungus gnats on my plant? They seem to be attracted to algae-infested areas.

Adrian Ling

Fungus gnats prefer environments where plants are grown in moist soil that is rich in organic matter.

You may want to grow your plants in such a way that the surface of the growing mix is an inorganic substrate that dries out quickly. For now, you can use yellow sticky traps to remove the flying adults.

Dracaena needs to be moved to a brighter spot to thrive

The Dracaena fragrans is in my living room and gets filtered sunlight. I apply a tablespoon of fertiliser monthly, being careful not to overwater. Recently, I have observed the new leaves becoming yellow and the sprout turning dark. What might be causing this? Is my plant in trouble?

Serene Chua

There may not be enough light in the living room for your plant to photosynthesise.

Move it to a brighter location, like the balcony, where it can get at least six hours of filtered sunlight daily. Filtered sunlight will cast a fuzzy, but still dark, shadow.

The yellowing leaves may be an indication that the plant needs more water. Water the soil thoroughly.

To determine whether the plant has been properly watered, stick a finger into the growing media. The media should feel moist, like a wet sponge that has been squeezed dry.

The plant should not be allowed to dry out completely.

Pot orchids in charcoal chips or dedicated media

I bought these new orchids at the Asia Pacific Orchid Conference. Should I repot them?

Annie Goh

Your newly purchased orchids are mostly potted in tightly packed sphagnum moss. The moss in this form will retain too much moisture and will suffocate the roots, causing them to rot.

Carefully remove the moss from the roots and prune damaged or rotting portions. Some gardeners will soak the plant in a fungicide solution before potting.

Use commercially available orchid-potting media or charcoal chips of an appropriate size.

The chips should be small enough to hold the plants in place, as pieces that are too large will cause the plant to wobble.

The air spaces between bigger chips will also dry the plant’s roots too quickly. However, chips that are too small will retain too much moisture and limit aeration.

As for your existing orchids, the same procedure applies. Prune the spent inflorescences, which are clusters of flowers on a branch or a system of branches, as well.

Chilli infested with broad mites

My Solar Flare chilli plant gets one to two hours of direct sunlight a day at my balcony. It flowers and its leaves are green, but has not fruited. I feed it half a teaspoon of organic fertiliser about once every three weeks. The young leaves and flower buds seem shrivelled lately. What is wrong? How can I get my plant to flower and fruit?

Susan Lee

The symptoms are typical of broad mites, a microscopic pest that is not visible to the naked eye. You can use diluted lime sulphur solution or abamectin, which are two pesticides that are effective against mites.

Ensure complete coverage of the plant and apply repeatedly to keep the pest population under control. Wear personal protection equipment and observe the withholding period – the time period that needs to elapse – before harvesting produce for consumption.

White specks could be sap-sucking pests

What are these white spots on my air plant? Are they harmful? What can I do to eradicate them and prevent them from appearing again?

Gan Sze Ying

A closer examination with a magnifying glass is necessary to tell what the white specks are. Common pests include sap-sucking insects like scales.

If they are pests, use a soft brush to remove them and soak the plant in pesticide. However, avoid using oil-based pesticides or soaps, as air plants are sensitive and may burn.

Use a chemical pesticide, such as cypermethrin, at half the recommended dose or lower. Spray it first on a small part of the plant to ensure there is no adverse effect before soaking the entire plant.