Root Awakening: Infested Sweet Prayer and bok choy

The burnt leaves of the Sweet Prayer plant may be due to drying out or excessive fertiliser salts at the root zone. PHOTO: DILEEP MARAR

Sweet Prayer infested with sucking insects

I have a plant that Google tells me is called Thaumatococcus daniellii, Sweet Prayer or Miracle Berry Plant. It has long stalks and on them are white bugs that look like fine fluffy powder. What are these pests and how can I get rid of them without chemicals?

Dileep Marar

Your Sweet Prayer Plant appears to be infested with soft scales, a type of sap-sucking insect pest. They can be difficult to control as they tend to hide in tight spaces found on the plant.

You can use environment-friendly pesticides such as neem oil and summer oil, which dissolve their wax and suffocate them. Repeated and good coverage of the plant is necessary to ensure the pests are killed and subsequent generations that emerge are also controlled.

Using less toxic pesticides has the advantage of not affecting beneficial predatory fauna in an outdoor garden, which can help with pest control too.

The burnt leaves of your plant may be due to drying out or excessive fertiliser salts at the root zone. Ensure that your plant is well watered during the hot season and do not overfertilise with chemical fertilisers.

If it is grown in a pot in a high-rise building, the use of tap water containing fluoride can lead to burnt leaves, as plants in the Prayer Plant family (Marantaceae) are reported to be sensitive to it.

Larvae on bok choy leaves

PHOTO: CINDY TAN

Some of the leaves on my baby bok choy look like they have been "drawn on". What are these markings and what should I do?

Cindy Tan

The leaves of your baby bok choy are infested with the larvae of leaf miners. The adults are small flying insects which lay eggs on leaves. Their young hatch from the eggs, then consume leaf tissues as they move along, causing the white tracks seen on the leaves.

Adult leaf miners can be difficult to control in an open garden. You may want to invest in a white fine netting that prevents them from reaching the plants. Organic pesticides like neem oil are reported to have some repellent effects.

Shrubs are Plectranthus and Gynura species

PHOTOS: LAI KWAI KUIN

What is the name of this plant and is it edible? It has a sweet fragrance resembling lemon when the leaves are rubbed. I labelled the second plant Okinawa spinach. Is the name correct? Also, is special care needed for these plants?

Lai Kwai Kuin

The plant on the left is botanically known as Plectranthus zeylanicus. Its furry leaves emit a pleasant citrusy scent and it is documented to be used in ayurvedic medicine.

The plant on the right is an unidentified species of Gynura which looks similar to the Okinawan spinach (Gynura bicolor). It differs from the Okinawan spinach with its shorter but broader leaves and a much redder leaf underside. The leaves are slightly furry to the touch.

Both plants can grow well with four to six hours of filtered sunlight daily. Growing media should be moist and well drained. They are easily propagated via stem-cuttings.

Plectranthus is commonly infested with moth caterpillars and Gynura is bothered by snails and slugs. Inspect the plants regularly and hand-pick the pests if the infestation is minor.

Kaffir lime could have suffered transplant shock

PHOTO: DON FOO

After repotting my kaffir lime plant, the leaves seem to have shrivelled. Why did this happen?

Don Foo

Was the root ball disturbed during repotting? It is a common mistake for many gardeners to remove excessive amounts of soil from the plant and expose the roots during such a procedure. This will cause transplant shock in sensitive plants.

The root disturbance damages the root system and prevents the plant from taking in water and nutrients. When exposed to direct sunlight, the plant will wilt and may die.

If you have done so, you may want to move the plant to a semi-shaded area to recuperate. Keep the ambient humidity high so that water loss from the plant is minimised. Depending on the extent of transplant shock and the damage to the roots, the plant may or may not recover.

When moving plants, reduce disturbance to the roots unless necessary. Move the entire root ball into the new pot and fill in with growing media. For the initial few days, the plant can be placed under shadier, cooler conditions to recover before moving to a place with more light.

Japanese Camillia performs poorly under tropical heat; pomegranate needs full sun to thrive

PHOTO: BRIDGET TEO

Is the plant in this photo the Japanese Camillia? It does not seem to bloom although there area few flower buds. What should I do to make the buds bloom?

I also have a pomegranate plant. The leaves turned brown and the flower buds dropped off. I suspected there was not enough nutrients in the soil or that the pot was too small, so I moved it to a bigger pot and added new soil. It soon grew more and fatter leaves, but some leaves also turned brown. Why did this happen and how should I pot the plant so the flowers can blossom into fruit?

These two plants are placed along a Housing Board corridor with partial sunlight.

Bridget Teo

From the picture, the plant you have is likely to be the Japanese Camillia (Camellia japonica). It can produce buds that do not open if the weather is too hot.

During the rainy season when it is cooler, there is a higher chance that the buds can develop fully and open. You can try growing the more heat-tolerant Camellia azalea which performs better in tropical, lowland conditions here.

As for your pomegranate plant, the issues may be caused by poor health due to the lack of light. It grows best under full sun outdoors, so you have to expose it to at least six hours of direct sunlight in a high-rise environment for better results.

This plant also prefers to be grown in a well-drained growing mix as it does not like prolonged wet feet.

  • 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.
  • 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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