Gardening

When uninvited pests come to visit, declare war with sustainable practices – and also an old-fashioned dose of hand-to-hand combat. By Helen Razer.

A time to kill those pesky garden pests

Destined for destruction: cabbage white caterpillars.
Credit: LAZARUS CHURCHYARD

Just like the life that engenders it, gardening is difficult, sometimes smelly and founded on a bedrock of lies. We would not live and certainly not give life to difficult delphiniums if we told ourselves the truth. Life depends in part for its endurance on fictions such as God or trickle-down wealth, and our gardens also grow in myth. These include: “It’s a cheap hobby” or “It’s so rewarding and you’ll have more delicious tomatoes by December than you know what to do with.” One of its more deluded propositions is: “Pests only inhabit unhealthy gardens.”

This is the ultra-organic intelligence. To say a slug is evidence of poor gardening, as some compost extremists do, is a bit like a shonky chiropractor telling you your bad mood is the result of poor spine alignment. You are in a bad mood because you hate your job, and slugs eat my oak leaf lettuce because it is delicious. You need to think about a career change and I need to put little dishes of beer out for the slugs. 

Your garden is not out of balance, but it might be if you use slug pellets instead of beer. There’s rarely any reason to use serious, slow-degrading pesticides. Honour the memory of my convict ancestors and let the garden gastropods get so drunk they drown in their own delight.

You will never win the War on Bugs just by planting heirloom cottage flowers by the lunar calendar. You can’t “Just Say No” to aphids. Or any of the other big threats I intend to tell you how to murder.

While it is not true you can build a garden that will deter all pests, it is true that healthy plants will resist attack better than something that looks more like a green rubber death scythe than the lovely sprouting broccoli promised on the label. I’ve told you to look after your soil and fertilise responsibly and you, in turn, have dug organic matter into your pots and watered with a regular fondness never shown for any other living thing. But still. The aphids. The caterpillars. The thrips.

I have relied for some years for a more cynical garden view from my associate Stu Burns. Founder of Melbourne horticultural business Garden Doctor, Stu will give it to me both straight and sustainable. When I told him my savoy cabbages were not so much brassica as they were the idle lacework of fat caterpillars and asked if I should grow marigolds between them, he told me: “Companion planting is largely bullshit.” Then he said, “Can’t talk. It’s a sunny day and I have pruning.” 

Which turned out well as I passed a decent afternoon of murder hissing, “You will never be a butterfly”, as invidious life left tiny bodies in my bare, murdering hands. This is a good practice. Pick the caterpillars off your plants and kill them. If, like me, you are a bit on the blind side, grow more reddish vegetables to turn up the contrast. I have found that my heirloom red cabbages – with which I have enjoyed success this season – made it much easier for me to see the grubs. Same goes for the brown fronds of the oak leaf and red kale. In fact, I suspect the neighbourhood birds see the caterpillars even more clearly than I do and help me out in my quest. 

Stu recommends hands-on solutions to many of our pest problems. Oftentimes, a physical barrier is the only solution; if you have possums, for example, you might need to build a wire cage around your strawberries or tomatoes. This is easier and less costly than it sounds. Just a bit of mesh, some wire and some snips should set you back about $30 and an afternoon.

Iris, my street’s best gardener, has come up with a range of prophylaxes in her 60 years of gardening, the most shocking of which is pantihose on cabbage. If you like, you could buy a fine net from a garden centre at great cost. Or, you could do as Iris does and shamelessly ask for hose donations and protect your brassica from cabbage moth in Natural Honey Beige. 

We can also look to helpful predators. A few years ago, I made friends with magpies on the occasion of a new lawn planting. I gave them kangaroo meat and they gave me vigilance on the ground against seed-loving birds. This is probably terribly unethical and I may be soon found shot by an angry ornithologist, but all organic gardeners will agree that encouraging good predators in the garden is A-OK. Local councils can often provide information on which good, or deserving, birds you should be inviting in.

And you should absolutely lure good bugs in. Companion planting might be soft science but you can certainly plant things that will encourage larger populations of good bugs. Talei Kenyon, education officer at heirloom seed company The Diggers Club, reminds us that Queen Anne’s lace, dill, tansy and yarrow are all pretty ways to tempt the useful hoverfly to come eat your aphids. These asexually reproducing, photosynthesising aliens ruin roses, spread disease and keep large populations of ants very happy. Stu explained to me in unasked-for detail the means by which ants sedate and maim aphids and keep them alive but paralysed. It’s gross. Happily, ladybirds are not at all gross and will also eat aphids. Attract them with yarrow, white cosmos, calendula and coriander. 

The other super-fun approach to pest control is insect warfare. You can actually purchase good bug larvae on the internet. Stu has bought some biological control insects, such as lacewings, but found they tend to not survive a Melbourne winter. They should be fine in subtropical zones, though. Talei suggests buying predatory larvae and mites at biologicalservices.com.au or bugsforbugs.com.au.

You can and should take this big-picture approach in a garden space of any size. Pests are likely to be your most serious balcony threat and it’s unfortunate but true that simply killing them with an indiscriminate pesticide will put things out of whack. You kill the good, including pollinators, with the bad and the bad always come back first and best. But we need to take a balanced approach to balance. It’s all very well and good to imagine a past whose plants were fed to health at the teat of Mother Nature. But they probably didn’t share a fence with Kerryn, who has ignored the gall wasp infestation in her lemon tree for years and forces me to carve and carve like a sustainable Jeffrey Dahmer to keep the blighters from my own garden.

With bastards such as gall wasp and fruit fly, you may need to spray. But here’s a non-toxic hint: encourage Kerryn to move and then buy a pruning saw. If you are blessed with a citrus tree and notice that leaf production is slowed or that your fruit is sparse or dry, look on your citrus branches for lumps. Some people cut these nodes housing the tree-killing creatures out with razor blades. As I can’t see well and quite enjoy legitimised brutality, I prune radically when there’s a serious infestation and mildly in good years. If you have a lovely fruit tree and suspect the sticky monsters that steal your sweet flesh are fruit flies, you will likely end up pruning as a first defence, but you must visit the national initiative preventfruitfly.com.au to identify the beast first and be best advised on future action. 

Pests appear in gardens of every area and elevation and their defeat often requires multipronged action. I have tried growing the pretty tansy to stop ants from entering my home and I have ornamental garlic around my roses to deter aphids, and nasturtiums a few metres away as a “trap crop”, the idea being that the vile little green plant lice will prefer the nasturtiums. 

But sometimes you’re going to need to use pyrethrum or a little homemade oil and/or soap spray to keep the bad guys down. 

Please do not mistake this for an urging towards pesticide. Really, the most dangerous tools you should use on garden pests are pyrethrum, borax (for ants, put it in honey) and manual violence. But even the most strictly organic horticulture cannot save us from pests.

There is no good reason for the domestic gardener not to observe sustainable practice. We do not live or die by the success of our crops and so we can afford to lose a few. But we can also afford to uphold our cynicism. So if I ever hear of you popping manure in a bullhorn or chanting and planting by the moon, I am giving my aphids your address.

This article was first published in the print edition of The Saturday Paper on Sep 20, 2014 as "A time to kill". Subscribe here.

Helen Razer
is a writer and broadcaster. She is The Saturday Paper’s television critic and gardening columnist.