Root Awakening: Plants are prone to fungal disease in humid weather (2025)

Chempedak fruit have fungal disease

My chempedak tree has finally fruited after more than a decade. Unfortunately, the fruit are mouldy and fall off. How can I prevent this from happening?

Esther Chan

Your chempedak fruit seem to have a fungal disease similar to that found in its relative, the jackfruit. Such diseases are common in warm, humid and rainy conditions.

Prune the tree’s canopy for better air circulation and ensure the tree is growing in well-draining soil. Remove any diseased fruit.

You can also protect developing fruit with copper fungicide, which is an organic fungicide that you can buy online and at large nurseries.

Plant could be the Red Egyptian Spinach

I found this plant growing in a pot of my cultivated plants and transplanted it into its own container. Is it a weed?

Jean Ang

This plant seems to be the Red Egyptian Spinach (Corchorus species). Its leaves are edible and they have a mucilaginous texture.

However, avoid eating it for now. Let the plant grow and produce flowers and fruit, so it can develop more identifying features.

Tillandsia ionantha turns red when flowering

Why are my air plant’s new leaves red?

Leong Tuck Sum

Tillandsia ionantha’s leaves turn red when it is flowering. You can see purple flower buds emerging from the centre of the plant. After flowering, the main plant will stop growing and new plants will emerge from between the leaves.

Apply pesticide to control whiteflies

I have had this bonsai for a few years and prune it every two months. Yesterday, I noticed whiteflies and a few black branches. I have sprayed the plant with soap. What is wrong and how can I treat it?

Adrian Ling

The black parts of the plant could be sooty mould that grows on the sugar-rich secretion from whiteflies.

These pests can be difficult to control and you need to be diligent in applying pesticides that have a rapid knock-down effect. Since this is an ornamental plant, you can use pesticides like cypermethrin, which is available for sale in most nurseries. Regular and thorough applications are necessary for adequate pest control.

You can also try sprinkling dinotefuran pellets around the root zone of your plant. This is a systemic pesticide that will be taken up by the plant and kill the whiteflies that feed on the pesticide-laden sap.

Monstera’s yellowed leaf could be due to multiple reasons

Is my Monstera sunburnt, facing a pest issue or just lacking in nutrients? I could not see pests on the leaves. It is on the floor of a balcony that gets filtered light in the morning and direct light in the afternoon. The soil is dry.

Sam Yeo

If the plant is being grown in a sunny spot, the yellowing could be due to sunburn, especially if it was previously in a shaded spot. The leaf may also have been burnt by coming into contact with heated window glass. Plants are best located away from window glass and need to adapt gradually to higher light levels.

The yellowing is likely not due to a nutrient issue, but check for sap-sucking pests like spider mites. These common pests appear as small red dots on the leaves and can be difficult to spot with the naked eye. If the infestation is minor, several applications of diluted soapy water can be used to suffocate them. A simple wipe with a wet cloth can also do the trick.

• Answers by Dr Wilson Wong, an NParks-certified practising horticulturist and parks manager. He is the founder of Green Culture Singapore and an adjunct assistant professor (Food Science & Technology) at the National University of Singapore.
• Have a gardening query? E-mail it with clear, high-resolution pictures of at least 1MB, if any, and your full name to stlife@sph.com.sg. We reserve the right to edit and reject questions.

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