Gardening with Wilson

Another Root Awakening column for the month of June 09 was published. This week, answers to three gardening questions were published.

The first enquired about white oil spray and how one can make some homemade pesticide spray for use on plants. White oil is basically is petroleum oil that is available in aerosol can form that is often applied as a leaf shine on plants. This oil can also be used in the same way like white summer oil (with emulsifier included) or super summer oil (without emulsifier) to control the populations of small sucking insects such as whiteflies, aphids, spider mites and mealy bugs upon contact.

A variety of  homemade sprays can be made. The most common being chilli and garlic spray which can be concocted at home using some chillis and garlic pounded to yield a juice which is then mixed with some detergent and then sprayed onto plants. The insecticidal power of such a concoction is limited and is quickly washed away by rain and broken down by intense direct sunshine.

The second question dealt with the appearance of yellow leaves in hibiscus plants. It is a very common occurrence in Singapore and can be brought about by iron deficiency. One has to correct the underlying causes that led to this and this include excessively wet or compacted soil, root rot disease, nematodes or elevated soil pH. Feed with a water-soluble fertiliser that contains chelated iron. Phostrogen is a good one to try.

The last question was about distorted leaves seen on bird’s nest ferns and basil plants which I reckon could be caused by thrips or spidermites. These tiny pests like to attack the young and tender new leaves of many plants which go unnoticed by most gardeners due to their very small size. The damage manifests itself as distorted leaves when the affected leaves grow larger with time. Spidermites can be eliminated using repeated sprays of white summer oil but thrips can only be killed by using the more toxic and systemic pesticide called Confidor. The use of the latter is discouraged on edible plants such as basil.