SHUI MEI IS INFESTED WITH SCALE INSECTS

What are the brown substances on the stems of the shui mei plant? They appear to be growing in numbers. How do I get rid of them?

Mooi Ho

Your shui mei (Wrightia religiosa) is infested with sucking pests that are most likely scale insects.

You can use a soft toothbrush to remove them and then spray an organic pesticide solution made from summer oil or neem oil on the plant. Such pesticides work by suffocating the sap-sucking insects.

Follow the instructions on the label on diluting the oils and spray during a cooler time of day to reduce injury to the plant. Test the spray on a small area of the plant to see if there are any negative effects before using it on the whole plant.

Depending on the formulation of the pesticide, repeated spraying every three to five days is needed to manage the pest population.

CHECK ROOT HEALTH OF BUDDHA BELLY PLANT

My jatropha is dying. It was growing well and had two rounds of flowering. I water only when the soil is dried out. What is wrong with the plant?

Christine Seah

The plant is commonly called the Buddha Belly Plant (Jatropha podagrica) and it appears to be starved of water.

Although this species is known to be drought-tolerant, it should not be allowed to dry out totally. The roots can be damaged and die as a result, which will lead to the plant becoming unable to take in water.

You may also want to take the plant out of its container and inspect the health of the roots. See if there are dead roots which may be totally dried or mushy. These can be pruned and the plant can be potted again for it to recuperate and grow.

Check for white, cottony masses which may be root mealybugs, sap-sucking pests that can weaken the plant over time.

If there are such bugs, wash the roots clean and soak the infested areas in a chemical pesticide such as cypermethrin. Pot the plant in fresh potting media.

PLANT IS CHINESE SPINACH

What is this plant?

Hsu Li Ren

It looks like the Chinese spinach (Amaranthus tricolor). It is likely the sharp-leaf variety. The tender young leaves can be harvested for consumption.

You can let the plant grow larger to produce flowers and seeds to be harvested for new crops.

• Answers by Dr Wilson Wong, an NParks-certified practising horticulturist, parks manager and ISA-certified arborist. He is the founder of Green Culture Singapore and an adjunct assistant professor (Food Science & Technology) at the National University of Singapore.

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