Root Awakening
Hibiscus likely infested with scale insects
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Unless the plant is small or weak, it may be best to prune the more infested portions first to reduce the pest population.
PHOTO: RAGHAVAN BEENA
Wilson Wong
How do I treat my hibiscus? The stems look infested. I have trimmed the branches and hosed the plants down, but the mites returned.
Raghavan Beena
Your plant seems to have been infested with scale insects, a type of sap-sucking pest common on perennial woody plants like the hibiscus.
Spray the plant with summer oil, which is available at local nurseries, to suffocate the pests. Spray during a cooler time of day, and do so thoroughly and regularly. Unless your plant is small or weak, it may be best to prune the more infested portions first to reduce the pest population.
Star fruit tree needs sunny spot
A lack of light can cause trees to produce elongated growth instead of fruit.
PHOTO: ROLAND CHAN
I have had this star fruit tree in my garden for more than 15 years. It once bore white flowers but no fruit. How do I get it to bear fruit?
Roland Chan
Your tree looks lanky. Note that fruit trees need direct sunlight for an entire day. A lack of light can cause plants to produce elongated growth instead of flowers and fruit.
Nitrogen-rich fertilisers will also result in the production of vegetative growth over fruit, so check the NPK (nitrogen, phosphorus and potassium) ratio of your fertiliser.
A specimen that has been raised from seeds will take longer to mature enough to produce flowers and fruit. It is better to grow trees from specimens that started as air-layered branches or grafts, which will be productive even at a smaller size.
Bloodberry is an ornamental plant
Some sources have documented its fruit to be toxic.
PHOTO: ANDREW WONG
What is this plant? Is the berry edible?
Andrew Wong
The plant is commonly known as the bloodberry or pigeonberry (Rivina humilis). It is a shade-tolerant ornamental plant.
Do not eat its berries. Although they are attractive, some sources have indicated that they are toxic.
Do not overwater aroid
The yellow leaf margins could be due to wet feet.
PHOTO: GARY CHAN
My plant is located near the window and gets light morning sun, but one of the leaves is turning yellow. What is wrong?
Gary Chan
Your plant seems to be an Alocasia, and it needs more light than what it is getting in its current location. It needs filtered sunlight – which casts a fuzzy shadow – for at least four hours a day.
Since this plant has been growing in a shaded location for some time, move it to a brighter spot gradually to avoid sunburn. You can also keep it under grow lights.
The yellow leaf margins could be due to wet feet. Alocasia needs an open, well-draining growing medium that dries out between watering sessions. Make sure its soil is not wet, as it can cause root rot and prevent nutrient intake.
Check for a spider mite infestation as well, as this is common with Alocasia grown indoors. Apply summer oil to suffocate the pests and ensure the plant is grown under optimal conditions.
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.
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