Infected papaya plant
The leaves of my papaya plant look spotted. The chlorophyll appears to cover the leaves unevenly. The plant has stopped flowering. What is wrong with it and how can I save it?
Yoke Yoong Mah
It appears that your papaya plant has been infected with a viral disease. Viral diseases are incurable and infected plants should be removed and discarded with municipal trash. Do not compost its remains. Sterilise all cutting tools that have been used to cut the infected plant.
Viral diseases are often spread via sucking insects, such as aphids in this case. Check your plants regularly for pests and take preventive action - such as disinfecting cutting tools and spraying organic pesticides - to reduce the chances of another infection.
Alse Daisy is a local weed
What is this plant that bears white flowers? Is it useful?
The plant commonly occurs as a weed locally. Its botanical name is Eclipta prostrata and common names include False Daisy, Mayweed and Stinking Chamomile.
There have been reported uses in traditional medicine, but avoid self-medicating without professional advice.
Due to their similar appearance, this plant can be confused with the Alligator Weed (Alternanthera philoxeroides), which is often sold as a vegetable in Little India.
The best way to tell them apart is through the flowers. Eclipta prostrata has daisy-like flowers, whereas those of the Alternanthera philoxeroides appear as a globe-like bundle of tiny white flowers.
Vegetables grown under sub-optimal conditions
I have been planting vegetables, but no matter the type of species, the seedlings have small, thin and folded leaves. An example is the pak choy. It has been about a month since I transplanted the seedlings. I use fertiliser such as chicken poo, 8+8+8, egg shells and coffee grounds, but they do not seem to work.
Your pak choy seedlings appear lanky and weak, which are signs that they are probably lacking in sunlight. This will also slow their growth.
Most leafy vegetables thrive when grown under at least six hours of direct sunlight. Ensure they are not shaded by large trees or any other structure nearby.
As for the cupped leaves, the cause is unclear, but it is likely environmental conditions. Ensure the root zone is well drained and not too wet, and that there is ample air circulation for the plant parts above.
Grafted desert rose produces pink blooms
When I got this plant a year ago, it had only violet flowers. Over time, white and violet flowers bloomed intermittently. Now, it bears red flowers as well as a different species with pink flowers. Why is this happening?
Your desert rose (Adenium obesum) is a grafted plant with two graft unions visible midway on it. These grafted portions likely produced the white and red flowers.
If you look carefully, the pink flowers come from the rootstock of the plant. There is a branch bearing the flowers that grew on the portion of the stem below the union, on the left side of the plant.
• 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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