Root Awakening: Give the orchid more water

Orchids need a moist environment

My orchid’s leaves turned yellow and brown before falling off. What’s wrong? I have reduced the watering and now spray the stems occasionally but to no avail. Some stalks have become bare.

Robin Chng

Your orchid looks like the Vandaceous orchid and the wrinkled leaves indicate that the plant is drying out and needs more water. The plant can be saved by moving it to a better growing location.

To achieve optimal results, orchids must be grown in a partially shaded or sunny location, depending on the species. A lack of light leads to weak, sluggish growth and makes the plant vulnerable to pest attack. The brown parts of the leaves may be due to pests or diseases.

Such orchids have aerial roots and are often grown with little soil. They require regular watering and should be grown in a moist environment to prevent them from drying out. Due to the lack of such conditions, it can be difficult to grow orchids in a high-rise environment.

Sweet potato plants can be affected by pests

My sweet potato leaves have white spots. Are you sick?

Annie Goh

The white spots could be due to damage caused by pests such as spider mites or thrips. They are very small and not visible to the naked eye. A hand lens can be helpful to check the presence of these people.

If the infestation is severe, you may want to remove the entire crop. Practice crop rotation and avoid growing the same species in the same location over a period of time.

Depending on the pest identified, you can spray your plants with summer oil, which will suffocate the pests. Thorough coverage and repeated applications are required to ensure adequate control.

Make sure to observe the waiting period – the time that must elapse after spraying the pesticide before harvesting the produce – and wash the plant thoroughly before cooking and eating the leaves.

Sweet potatoes are a sun-loving plant and should be grown outdoors under direct sunlight for best results. A healthy plant is less susceptible to pest attacks.

Use pyrethrins to control the pest population

What is this white pest on my okra plant? I tried to get rid of it with spinosad and abamatin, but neither was effective.

Adrian Ling

The pest cannot be clearly seen in the image submitted. It is probably a cicada commonly found on okra (Abelmoschus esculentus). It sucks in plant juices and can spread incurable viral diseases. It hops or jumps when disturbed.

Use a pesticide that kills the pest quickly. Try pyrethrinswhich are derived from relatives of the chrysanthemum, or come into contact with chemical pesticides which have the same effect.

The plant grows towards the light source

Why are my Monstera Thai Constellation’s leaves curling outward? Keeping takes place in a partially shaded area.

Tan Li Siang

Are you growing your Monstera in an apartment? If this is the case – and you keep your plant in the hallway or on the balcony – the light usually only comes from one direction.

Plants require sunlight for photosynthesis and naturally orient themselves in the direction of light.

Some gardeners rotate their plants to achieve a symmetrical growth habit. However, this may not work for the Monstera because it has a peculiar arrangement of leaves along the stem and the rotation can spoil its appearance.

The chili plant is infested with broad mites

I have three chili plants in pots on my balcony, but one has abnormal leaves. What’s wrong?

Tan Eng Kiat

Your plants appear to have a widespread mite infestation. This is a common pest of this plant species.

You can spray the affected plant with pesticides such as lime sulfur or abamectin. To ensure adequate control, repeated and thorough application is essential. Be sure to consider the waiting time before harvesting the plant.

• Answers from Dr. Wilson Wong, an NParks certified practicing gardener and park manager. He is the founder of Green Culture Singapore and Adjunct Assistant Professor (Food Science and Technology) at the National University of Singapore.
• Do you have a question about gardening? Email it to [email protected] with clear, high-resolution images of at least 1MB (if available) and your full name. We reserve the right to edit and reject questions.

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