Gardening in a hot climate can be wonderfully rewarding but it does have its challenges. Among the most disheartening is the veritable army of creepy-crawlies and no-see-ums that thrive in tropics and that see your lovingly tended plants as nothing less than a smorgasbord of gourmet delights.
You know how it goes. Your beautiful frangipani and your ixora look as if someone has thrown dirty oil over their leaves, the stems of your oleanders are covered in some sort of white powdery substance, and the leaves of your tomatoes are mostly gone. Or maybe white webs are covering the underside of your guava leaves while your hibiscus leaves are all shriveled near the centre.
If any or all of these things are happening in your garden, don’t despair. There is help but first, it’s helpful to know which particular pest is affecting a plant so you can target your defense more effectively.
Aphids are among the most common of the pests you will encounter in your garden, no matter how well you look after it. These tiny pests suck plant sap, hence the shriveled appearance of your leaves. If the affected plant is mature, you can try hosing it off with a powerful jet of water. You can treat a more tenacious infestation with insecticidal soap which is available at most garden centres. Like whiteflies, mealy bugs and scales, aphids are known to transmit plant viruses so it’s important to control infestations.
Whiteflies are another pest that can be treated with insecticidal soap. These small insects suck plant sap as aphids do and can be found on the underside of leaves, which they cover with a white, webby substance. Besides the harm done to the plant by the whitefly’s toxic saliva, the pest also excretes a honeydew which encourages mold growth. Light horticultural oil, malathion or pyrethrin can also be used to treat whiteflies. You may also want to plant marigolds, basil or nasturtiums around affected plants, as these secrete oils that appear to repel whiteflies. Try to vary the methods used to keep them under control, as they appear to have developed immunities to some pesticides.
If you’ve ever tried to grow hibiscuses, you’ve probably encountered mealybugs. These are another class of sucking pests. They cover their bodies with a white waxy substance and can usually be found in groups. Mealybugs can damage citrus, ferns, orchids and sugarcane in addition to being common on hibiscuses. Leaves will wither, turn yellow and drop. You can wash off small numbers with cotton dipped in rubbing alcohol but for larger attacks, try insecticidal soap or neem.
Caterpillars are another class of pest that may lay waste to your garden or, at least, to certain plants. If you like butterflies, you might want to just ignore the appropriate caterpillars. The tomato hornworm is no sluggard at defoliating those tomato plants you’ve so carefully nurtured, so keep an eye out for it. You can handpick caterpillars or spray the affected plants with Bt. Caterpillars are also susceptible to pyrethrin.
So now you know a little more about the pests that may make your gardening life hell and you know about the range of weapons that should be in your arsenal. The best thing, though, is to try to prevent infestations from the start. Planting plants that are not very susceptible to pests, catching pests before their populations grow out of control and checking nursery plants for problems before you bring them home will help to minimize unwanted incursions. The one thing you don’t want to do is let loose with a pesticide that will be toxic to both the pests and beneficial insects like ladybugs, which feast on aphids. Sevin, for instance, kills everything while Bt works only on caterpillars.
