Pest control

Published March 22, 2015
Trailing tomato ‘Sun-Gold’
Trailing tomato ‘Sun-Gold’

Q. I grow seasonal vegetables in the backyard of my house in Karachi. The yard also has chikoo, grapefruit, lemon, lime, fig and guava trees. Fruit and vegetables crop well but I am unable to harvest most of the produce due to fruit fly infestation. These pests destroy everything, including tomatoes and cucumbers. I have tried fruit fly traps but the result is negligible. Advice desperately needed.

A. Fruit flies or ‘Tephritidae’ are serious pests which, I am sad to say, are extremely difficult to control using organic means but it is good to know that you tried traps. Keeping the garden completely clear of fallen fruits, disposing of them well away from your home and not in the compost heap, can help reduce the fruit fly population as can the rapid removal of any massed weeds, finished plants and fallen plant debris in which they can hide and also breed.

In respect of the fruit trees, please try grease bands: these are six to nine inch wide strips of jute sacking or other coarse cloth, liberally coated in grease / sticky, old engine oil or some other ‘gunge’ which will firmly adhere to the cloth. Tie this around the tree trunks about mid-November, change them every three weeks until mid-February and carefully dispose of them in a sensible manner. The idea is that the majority of fruit flies begin their life cycle on the ground and, in late autumn / early winter, crawl up the nearest tree to keep warm in bark cracks from where, when spring warmth arrives, they head, hungrily, for the nearest fruit under formation, burrow into it and lay eggs beneath the skin to perpetuate their horrible existence. This method can, especially if implemented each year, be very successful, although, obviously, it does not apply to seasonal vegetables. Controlling fruit fly in the trees should, in due course, also reduce and then eradicate the problem with your tomatoes and cucumbers, etc.


Pests are harmful, but so are pesticides. However, there are alternatives to spraying poison on your plants


Q. I have a gummosis problem in my apricot orchard as well as a problem with termites. Can you please tell me how to resolve these issues?

A. A lack of essential nutrients in the soil or / and unsuitable soil conditions are the usual case of gummosis in fruit trees and apricots appear to be especially susceptible to this. It looks terrible but, as long as soil is brought up to standard, does no lasting damage to the trees. You need to rebalance the soil — a soil test may help and this can be done using one of the soil testing kits now available in some garden supply stores — ensure good drainage and once achieved, to maintain soil health all year round.

As for termites, unfortunately there is no reliable organic control although laying a four-to-six-inch deep layer of crushed charcoal beneath the top soil of new growing beds, say at a depth of two feet below the surface, can prevent termite infestation for a number of years although, personally speaking, I have not monitored the lasting result. You may need to seek professional, therefore chemical, intervention.

Q. I grow marigolds, in pots, each year in Karachi but have had problems for the last three years. Some of the plants get covered with a fine, white, spidery thread. I dispose of the affected plants and change the soil before planting anything else. I change the soil in the pots each year, too. I spray the plants every year while they are three to four inches high but the problem persists. What is it and how to eradicate it?

Tangy lemons
Tangy lemons

A. Spider mites or ‘Tetranychidae’ appear to be the cause of the problem. Invisible to the naked eye, these insect pests are capable of spinning incredibly fine nets which festoon plants during warm to hot weather. They can be eradicated by brushing off the webs then spraying the plants, thoroughly I must add, with warm water. I suggest that you use garlic water or hell-fire spray, if possible. Recipes for both have been supplied in previous columns. Your soil hygiene sounds excellent but there is absolutely no need to spray plants unless there is a problem and even then, only organic sprays please.

Q. We have grown tomatoes and the plants are fruiting but the leaves are becoming brown and dying. Do we need to do something or is this a natural phenomenon?

A. It is only natural if the plants are nearing the end of their productive lifespan, but if they are not it is a clear indication of a pest problem or the damage is caused by watering the leaves when the sun is up. Remove any brown leaves as soon as you spot them, dispose of wisely and not on the compost heap in case of fungal infections, and take care when watering. Water the soil around the plants, evening time is preferable, not the plants themselves. If visible pests appear, please let me know.

Q. In your articles you talk about ‘organic compost’. Please tell me how to prepare this?

A. Keep your eyes on this column please as I will be writing on this very subject soon.

Q. I am trying to learn different methods of plant propagation and have been successful with ficus, carnations and some others but most of the ‘champa’ cuttings I took last August have failed. Where did I go wrong and what is the best time of year to try ‘champa’ again?

A. Not knowing from which part of the shrub cuttings were taken or their length, I cannot say where you went wrong. ‘Champa’ or ‘Frangipani’ cuttings should be taken from the end of branches, be approx six to nine inches in length, have any flower buds removed, be planted in good compost up to one third of their length, the pots placed in partial shade and kept watered. Cuttings are best taken just before and during the summer monsoon.

Please continue sending your gardening queries to zahrahnasir@hotmail.com. Remember to include your location. The writer will not respond directly by email. Emails with attachments will not be opened.

Published in Dawn, Sunday Magazine, March 22nd, 2015

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