Cantaloupe plant has mildew disease; other plants may be a Ludwigia and Spider Flower
I recently found yellow spots on the leaves of my cantaloupe plant (Photo 1) and they are killing the leaves and plant. I have used neem oil twice, but it does not seem to work. What else can I do? Also, what are these two plants (Photos 2 and 3)?
Your cantaloupe plant has mildew disease, which is common in this group of plants.
It is recommended you grow the plant under a clear shelter to protect it from the rain yet allow direct sunlight through. Ensure ample air circulation by spacing plants apart and spray fungicides to reduce the incidence of disease. A diluted milk solution provides some control in such foliar fungal diseases.
Regarding the other plants, without close-up pictures of the flowers, their actual identities can be difficult to ascertain.
From the morphological features, the picture in the middle shows a plant that is likely a Ludwigia species.
Two species of this genus are commonly seen in Singapore - Ludwigia hyssopifolia (Water Primrose) and Ludwigia octovalvis (Primrose Willow) - and they sometimes occur as weeds growing in flower pots with moist soil. They produce yellow flowers.
The picture on the right is likely Cleome hassleriana (Spider Flower), which produces small violet-hued flowers. The weed is a host plant of caterpillars of local butterflies.
Marks on rosemary leaves due to sucking pests
My rosemary plant's leaves have turned yellow and spotty. How can I treat it?
The brown mottled marks could be a result of sucking pest damage.
Check for spider mites or lace bugs on your plant. Deal with spider mites using summer oil or neem oil, which are sold at local nurseries. For lace bugs, manage them with a pyrethrin pesticide, which is derived from insecticidal chrysanthemum flowers. Repeated applications are often required to manage the infestation effectively.
Wash your harvest thoroughly to remove pesticide residues before consuming it.
Redflower Ragleaf's young leaves can be eaten
I understand this plant is Blumea lacera. Our helper from Myanmar said it is a common vegetable in the country, but I cannot find literature on it as a vegetable.
Lim Shuh Chaang Esther
The plant is botanically known as Crassocephalum crepidioides and its common name is the Redflower Ragleaf. It occurs mostly as a weed in local landscapes and can grow quite large.
The young tender leaves are eaten as a vegetable and the plant is reported to have uses in folk medicine.
Chat with plant experts Wilson Wong and Edgar Raeben George on understanding and making your own growing media. The event takes place today over National Parks Board Facebook Live from 3 to 4pm.
• 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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