Wrap young fruit to reduce injury and infection
My nangka fruitlet had a brown spot on its green skin. It then grew larger, turned black and the fruit eventually dropped off. Why does this happen?
The fruit could have been infected by a harmful fungus or it could have had a secondary infection brought about by initial injury to the young fruit by organisms such as insects.
One way to prevent this is to wrap the young, developing fruit so that organisms cannot get to it and cause damage.
Next, avoid handling the fruit excessively as this can cause injury to it too.
It is best to also remove infected fruit to prevent the spread of disease.
To reduce the incidence and spread of fungus on fruit, you may want to prune the canopy of the tree slightly to allow for sunlight penetration and air circulation.
Fungicide sprays should be used only as a last resort.
Propagate lavender with tip cuttings
My potted lavender dries up even though I try to keep the soil moist. Why does the stem turn brown and how do I prevent this from happening?
The lavender (genus - Lavandula) is a plant that prefers to grow in well-draining media, where excess water drains away quickly, and one that dries out fast.
Often, plants which are imported from overseas nurseries are grown in media such as peat moss or cocopeat, which hold excessive amounts of water for growing lavender.
However, it is not practical to move all media from the root zone and grow the plant in a new well-draining medium - the process will damage the plant's roots and lead to transplant shock that often results in death of the plant.
Take tip cuttings from the plant and try to root them in coarse, aquarium gravel. Once the cuttings start to root, carefully transplant them into a well-draining medium which is made up of small expanded clay pellets, pumice and some burnt earth.
The proportions to mix depends on growing conditions such as the amount of sunlight, watering regimen and type of pot used.
Lavenders demand a sunny location to grow well. They should be sheltered from the rain.
Finally, the lavender prefers a drier climate to grow well.
Singapore is a humid country with high rainfall, which makes it extremely challenging to grow lavender here.
Moisture stress a possible cause of split fruit
My bananas always split along each fruit before they ripen. What do I have to do to harvest them without such blemishes?
Did the skin of your fruit split while it was still on the plant or after it had been harvested?
In the first instance, it could be due to moisture stress from heavy rainfall or irrigation after a prolonged dry spell. Such a great fluctuation in the amount of water given to plants can be one of the causes for the skin of edible fruit to split.
Keep the root zone of your plant evenly moist and apply a layer of mature compost which can help to reduce the rate of evaporation of water from the root zone. Compost serving as a mulch can also help to reduce weed growth.
Make sure that the fruit, when they are still on the plant, are shaded. Also, feed the plant well during production.
For fruit that have been harvested, the split skin could be due to a too-high ambient air humidity - over 95 per cent - during the later stage of fruit ripening.
To prevent this from happening, ensure the environment is well ventilated.
Tip: Inject colour with Dracaena's new cultivar which has lime-green leaves
People are familiar with the foliage plants from the genus Dracaena which are popular houseplants.
Locally, you can find the traditional, all-green version as well as various cultivars with differing leaf variegation.
A relatively new cultivar in the local nursery trade, called the Dracaena deremensis "Limelight", has glossy, electric lime-green leaves which are sure to add colour to a home or an office.
Like most Dracaena, this cultivar is suitable for growing in flats. It thrives in a location where it can be exposed to filtered sunlight for at least four hours daily. Hence it should never be displayed for too long deep inside the apartment or office.
The soil should be kept moist at all times and a slow-release fertiliser should be applied to encourage healthy growth.
Exercise caution when harvesting wild plants
Are these small green leaves from the Dandelion Root plant and are they edible?
Chan Lay Eng
The plant is a common weed in Singapore. Its botanical name is Tridax procumbens and is commonly known as Coat Buttons.
Like the Dandelion, both are members of the daisy family (Asteraceae). There are reports of the leaves being used in cooking and consumed as a vegetable.
However, avoid harvesting materials from wastelands and roadside for consumption as environmental pollutants may be present in the soil and these can be absorbed by the plants growing there.
The flowers and leaves are used in Ayurvedic treatments for a range of ailments.
• Answers by Dr Wilson Wong, a certified practising horticulturist and founder of Green Culture Singapore (www.green culturesg.com). He is also an NParks-certified park manager.
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