Chilli plant may be infested with spider mites
What is happening to my chilli plant? Several leaves have the same symptoms. I have sprayed an organic fungicide every other day for a week. What can I do to stop the spread?
Check if the tiny red dots below the leaves move around, as they could be spider mites, which are sap-sucking pests. They are prevalent in stressed plants.
Is the area where your plant is growing very windy and dry? Such environmental conditions are conducive for spider mites. A high-rise environment does not have beneficial fauna to manage the mites. Also, if it is sheltered, the pests cannot be washed away by rain.
To manage the problem, prune the heavily infested leaves and use a strong jet of water to wash off pests on a regular basis. Summer oil, available for sale in most nurseries, can also be sprayed at repeated intervals to keep pest levels low. Note that thorough coverage on all parts of the plant is required.
Lavender needs direct sunlight to thrive
My lavender plant has a few flower buds, but why do their stems fall? I spray water on the plant on alternate days and place it on my balcony, where there is much sunlight.
The lavender plant is not an indoor plant and does not thrive in shady areas. It needs at least four hours of direct sunlight a day. A lack of sunlight leads to an unhealthy, disease-prone plant.
Most lavender plants sold locally are imported and grown in coco peat, which holds a lot of moisture. The lack of sunlight means the plant does not need to take up much water and also reduces the rate of evaporation. As a result, the plant experiences constant wet feet, which can cause the roots to die and the plant to be infected by soil-borne diseases.
Place the plant in a sunny spot and allow the growing medium to dry out slightly before watering again.
You can take tip cuttings and propagate them. These can be grown in an aerated mix consisting of gritty materials that permit drainage.
Star of Bethlehem is a beautiful but toxic plant
What is this plant? It grows white flowers now and then. How do I take care of it and propagate it?
This plant is botanically known as Hippobroma longiflora and its common name is Star of Bethlehem. It self-seeds readily in gardens and can be propagated by stem cuttings.
Note that all parts of the plant are poisonous. The white sap it exudes contains an acrid poison (lobelanidine) that produces a burning sensation in the mouth and throat and irritates the eyes, even causing blindness. Keep this plant away from children and animals, and wear gloves when handling it.
Melon plant may be eaten by caterpillars
Something is eating the young leaves of my melon plant. How can I deal with it? Also, what are the brownish spots on the leaves?
Your melon plant may be infested with young caterpillars. These chewing pests may appear when the weather is moist and warm, which is also when plants produce rapid young growth.
The caterpillars are small, consume young parts of the plant and may spin a web that holds leaves together. Their damage can appear as brown or black dots, which are the pests' waste products.
If the infestation is not serious, you can pick the caterpillars off by hand and discard them. To prevent future infestations, use a physical barrier - such as fine white netting - to cover your plants. This will prevent flying adult insects from laying eggs on the plants. Alternatively, you can spray a selective pesticide called dipel, which is based on the microbe Bacillus thuringiensis subspecies kurstaki (Btk), to treat the infestation.
Tomato may have fungal disease, needs to be fed and watered
I have been growing my tomato plant since June 2021. It now has brown spots around a few branches of the lower leaves. The first few sets of the older leaves are starting to turn yellow. What is happening to my plant? It has grown to more than 1.5m tall and is developing flowers.
Tan Chew Hwa
The brown spots may be signs of fungal disease. If you are growing this plant in an apartment or high-rise setting, ensure that it gets four to six hours of direct sunlight a day. Prune your plant and spread its branches to ensure the canopy has ample air circulation, which will reduce the likelihood of disease.
You can spray organic fungicides such as copper soap or lime sulphur as a preventive method. Always observe the withholding period between spraying and harvesting the fruit, and wash produce thoroughly before cooking or consumption.
The lower leaves could be yellowing due to a lack of water or nutrients such as nitrogen. When plants grow, they take up a lot of water. It is best to grow your tomato plant in a large pot with enough soil to hold water.
Water more frequently during the hot and windy season. Also, feed your plant regularly as rapid growth means it will have increased nutrient needs.
The yellowing of older leaves is expected of larger plants and is not a cause for concern. Make sure the plant gets enough light as the lack of it can cause leaves to die too.
However, if many leaves take on a lighter green or yellow hue, you may need to feed your plant with a nitrogen-rich fertiliser - for example, processed chicken manure or other organic fertilisers. Plant food that is rich in nitrogen promotes the production of lush leaves over flowers.
- 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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