Root awakening

Small strawberries.
Small strawberries.PHOTO: O.T. GOH

Lack of pollination the reason for small strawberries

I grow strawberries in my office. The plants are healthy and are in an air-conditioned environment. They have lots of flowers, but small fruit. Why is this so? O.T. Goh

Small strawberries are a result of insufficient pollination. The flowers are not pollinated by insects as they are grown indoors.

As such, you will have to pollinate the flowers by hand to get larger fruit. You can use a small paintbrush to brush the centres of the flowers to help with the transfer of pollen.


Dogfennel has fine, feathery leaves

What is the difference between this plant and dill? Can it be eaten?

Anna Khoo


PHOTO: ANNA KHOO

The plant is Dogfennel, which is also known by its botanical name, Eupatorium capillifolium. It should not be confused with the true dill, which is known botanically as Anethum graveolens.

It is important to know the botanical names of plants and do thorough research before eating them or using them to treat medical ailments.

Dogfennel is a shrub-like plant that has woody stems that grow upright. It produces fine, feathery leaves.

True dill has blue-green leaves. It is largely a herbaceous plant with no woody tissue. It cannot grow tall and has leaves that grow in a rosette formation.


Curling leaves result of sucking pests


PHOTO: JENNY TAN

The leaves of my golden apple plant are curled and misshapen (above). I put the plant on the patio, where it gets about six hours of sunlight. Why does this happen?

Jenny Tan

Small sucking pests such as mites, thrips and aphids could be attacking the young, developing leaves. You may need to inspect the new leaves closely to spot these insects.

You can use environment-friendly pesticides such as neem oil or summer oil. However, the right dose of pesticide needs to be applied carefully. The plant's developing tissues are tender and prone to damage when chemicals are used.

Apply pesticides during the cooler part of the day to reduce the incidence of damage to the plant.


Plumeria affected by fungal disease


PHOTO: KRYSTAL CHOONG

The leaves of the plumeria tree in my garden have orange powdery spots (above), which are mostly on the underside of the leaves. They also turn yellow. I remove them and fresh, healthy ones grow, but they also get infected. What should I do? Once the tree grows taller, I will not be able to remove the leaves.

Krystal Choong

The orange spots are caused by a fungal disease called Frangipani Rust. It is specific to the frangipani and is difficult to eradicate. The plant's botanical name is Plumeria cultivar.

This infection comes about during the wet weather season in Singapore. When leaves have these spots, it is necessary to remove them.

Avoid composting the plucked leaves or using them as a mulch as this can cause the disease to spread.

The frangipani should be grown in a sunny, dry and well-ventilated spot to reduce the incidence of the disease.

Chemical fungicides such as myclobutanil can be used to reduce the incidence of the disease, but they may not be easily available to home gardeners. Repeated use is often necessary, though the chemicals can be harmful to the environment.


Scale insects infesting aloe plant


PHOTO: RIA VAN DER MERWE

Why does my plant have white spots on its leaves (above) and will it die?

Ria Van Der Merwe

It appears that your aloe plant - given the plant's features, it is not likely to be the aloe vera species - is being infested by scale insects. Use a soft toothbrush to remove the sucking plant pests.

For now, use organic pesticides such as summer oil or neem oil to spray the plant. These oils may be harmful to your plant, so test it on a small area to see if there are any negative effects before using it on the whole plant.

Follow the instructions on the label on how to dilute the oils and whether repeated spraying is needed to control the insect population. If the pests return, you may need to use chemical pesticides instead.

•Answers by Dr Wilson Wong, a certified practising horticulturist and founder of Green Culture Singapore (www.greenculturesg.com). He is also an NParks-certified park manager.

•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

•In last Saturday's Root Awakening column, Dr Wong wrongly identified a cactus as the Cereus repandus, or Peruvian apple cactus. He has clarified that its correct botanical name is Cereus hildmannianus. He notes that the plant is also often identified as Cereus peruvianus, though this is wrong.

A version of this article appeared in the print edition of The Straits Times on July 15, 2017, with the headline 'Root awakening'. Print Edition | Subscribe