Gardening – Dealing with pesky pests

Autumn is traditionally the time for a clean-up in the garden. While in cooler climes this might refer to raking up piles of leaves and burning them, in our more subtropical region it is more likely to involve lots of pruning. Unless you have a park-like garden with many big deciduous trees, there is usually no need to be raking up leaves. For a light scattering of leaves on the lawn, just mulch them up with the mower.

Leaves that fall onto the garden make excellent mulch, smothering weeds and feeding the plants and beneficial insects, so they are best left where they fall.

Fallen fruit is a different matter. These are often infested with the caterpillars of various pest species, such as guava moth, codling moth and leaf roller moth, so are best gathered up and composted or mown over. This reduces the quantity of these pests in the following growing season.
Many gardeners recommend clean-up pesticide sprays to reduce pest numbers before winter. I’m getting less keen on this approach as many pesticides also reduce the number of beneficial insects, such as parasitic wasps and pollinators, just as they are preparing for hibernation. If you do have a serious outbreak of bugs at this time, then a spray of Neem oil provides a relatively effective, low toxicity control.

In my so-called pest-proof greenhouse (with insect screening on all openings) that I use for tamarillos, tomatoes, chillies and other members of this pest-prone family, I have had a serious outbreak of whitefly. This is my own fault really, as last autumn I didn’t take seriously the presence of a few whiteflies that had established themselves. Some half-hearted attempts at control meant the population staggered on through winter and then exploded in spring.

This autumn, I’m taking a more extreme approach. All the plants in this greenhouse are potted and all members of the tomato family can be grown as perennials, cut back hard and allowed to resprout. So, all the plants are being cut back to leafless stems and removed from the greenhouse, which is then swept out and sprayed with a six per cent solution of hydrogen peroxide. That’ll wipe out pretty much everything and, as a bonus, will also clean up any algae on the windows. This converts to water and oxygen quickly, so within a day of applying, I can move the plants back in, carefully checking the stems and soil for any sign of pests.

Pruning is an important pest control procedure in the garden. Observant gardeners will notice that dry stems of plants such as cannas and small twigs on grapes and the like may have a slightly serrated look. This is the characteristic egg laying habit of passion-vine hoppers. Pruning these off now and disposing of them either in the compost heap or by burning them, will dramatically reduce the population of this troublesome pest next summer. As the saying goes, a stitch in time saves nine!