Dogfennel reported to have toxic compounds
I came across this plant along a Housing Board block walkway near Crawford Lane. It is very attractive and I want to grow it on my balcony, which receives full sun and is windy too. What plant is it and is it readily available in nurseries? How do I take care of it?
Numerous questions have been asked about this plant, which is commonly known as dogfennel.
Its botanical name is Eupatorium capillifolium. In Singapore, it is commonly mistaken for the dill plant (Anethum graveolens).
The fine feathery leaves of the shrub-like dogfennel, when finely cut, resemble those of the dill plant.
The true dill is a small herbaceous plant that grows similarly like the common coriander, except it has blue-green leaves.
Note that these two plants are not related. Dogfennel is reported to contain alkaloids, which may be toxic as these compounds can affect liver function.
This plant is sold in most local nurseries and can be propagated via stem-cuttings. It thrives in a sunny and well-drained location.
Insufficient sunlight for desert rose; seedlings may have transplant shock
My parents' two pots of desert rose have not been blooming for more than a year, despite having their soil changed. There are also four plants growing from fruit seeds, but I am unsure what they are. The leaves at the bottom had brown specks and then wilted off. Is it because the roots are damaged after being transplanted?
Is your desert rose plant placed below the parapet of your corridor? If so, the plant may not be receiving sufficient sunlight as the parapet is shading it from the light.
The desert rose thrives in a sunny location and should get at least six hours of direct sunlight for robust growth and flower production.
The seedlings are likely those of the guava plant. The decline of the seedlings could be caused by several factors.
One of them could be transplant shock, where roots of the plant are damaged and/or not acclimatised properly after the move. Transplanted seedlings need to be placed in a cooler and shaded environment for plants to recover before moving them to a sunny location for growth.
At times, a plastic cup punctured with holes may need to be placed over transplanted seedlings to help conserve moisture and reduce excessive water loss.
Mulberry plant is infected with a fungal disease
I have a pot of mulberry plant. Its leaves have white spots on the underside that turn brown subsequently. The leaves will finally wither as well. Are the spots the result of a pest infection? What causes the spots and how should I treat the problem?
Tea Ann Lee
From the white masses found on the underside of leaves, your mulberry plant could be infected with a fungal disease, most likely powdery mildew.
Ensure that your plant is grown in a sunny and airy location.
As mulberry is generally a robust plant, it can take some pruning of badly infected leaves to reduce the amount of spores that will be spread to the surroundings.
Next, to prevent and lower the incidence of disease, apply a fungicide.
Lime sulphur, Bordeaux mixture (a copper-based mixture) and even baking soda are reported to provide some control as they can be sprayed on leaves to create a layer of protection. But these organic measures get washed away by rain easily and need repeated applications to be effective.
You can use chemical fungicides such as Captan, which are available for sale in local nurseries.
They are usually more potent and you will need to follow the information on the label such as on dosage, withholding period and wearing of personal protective equipment to ensure safe usage.
Brazilian spinach plant infested with thrips
I found tiny black specks underneath the leaves of my Brazilian spinach. What are they and how do I get rid of them?
Chian Hwey Miin
The leaves of your Brazilian spinach may be infested with thrips, which appear as small, longish insects. They rasp the leaves and leave behind silvery patches. They are very difficult to control using most pesticides, organic or chemical.
The most effective pesticide to manage thrips is spinosad and it needs to be rotated with others to reduce the likelihood of pest resistance.
Compost made from food scraps is a good soil amendment
I am doing composting at home. I have a good amount of compost made using tea leaves, vegetable waste and some yellow leaves from my plants. Can I mix it with perlite and use it to grow edibles or do I need to add something else?
It appears you are making compost from food scraps, which is a good initiative to reduce food waste.
Such composts, when mature, are generally low in nutrients but its organic matter makes it a good soil amendment.
In this case, you can use the compost to break up and lighten clay soils in your garden plots and potted plants.
It is not recommended you use it on its own as it can retain too much moisture for many plants.
• 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 firstname.lastname@example.org. We reserve the right to edit and reject questions.