The first gardening article I ever wrote was about controlling scale, more decades ago than I care to count.
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If I remember correctly I offered a recipe for homemade oil spray, which I won’t inflict on you, as it involves a lot of shaking and fast spraying, and also burns the leaves if applied when the day is over 24 degrees.
Soon after, a commercial product arrived on the market, Pestoil, which did much the same, applied a light suffocating coat on those pesky creatures that look just like tiny scales and suck the juice from the leaves and shoots.
The scale insects will turn the leaves and new shoots a withered brown and will eventually kill them, as well as injecting toxins to add insult to injury. A badly scale-infested citrus tree can die in a few months.
But finally, so many years later, I think the best way to get rid of scale is to do nothing. If you spray pesticides you’ll also kill the predators that eat the scale. I spent four years trying to get rid of the scale on our indoor coffee bush. I tried Pestoil, homemade oil, spray sponges, squishing with my fingers and scrubbing with an old toothbrush. Each method worked – for about a week. Then new scale appeared – tiny, pale green and almost impossible to see till they turned brown and the leaves and stems withered as a result of their sucking out the sap.
Then last summer Bryan acquired a trolley and hauled the poor coffee bush outside. The leaves were scale free within a fortnight. No scale appeared when it over-wintered indoors this year and it is happily putting out scale-free shoots and a surprising amount of winter-grown fruit as I write this.
We usually refer to ‘‘scale’’ as though it were just one pest, but there are many different forms of scale insects, all of which have their own food preferences. Luckily the predators that eat scale don’t care which kind they are. Many small birds adore eating scale – treecreepers, cuckoo-shrikes, pardalotes, silvereyes, firetails, honeyeaters, blue wrens, some finches (during nesting). Ladybird larvae, lacewings, hoverflies, chalcid wasps and damsel bugs eat scale.
Scale problems are worse indoors, where there is a severe shortage of treecreepers and pardalotes as well as hoverflies, or where the trees or bushes are overshadowed by other trees so the birds don't notice the delicious scale on the citrus leaves and solve the problem for you. Plant lots of native shrubs and flowering plants to encourage pest predators.
Try to keep ants at bay if you have black or brown scale. Ants also deter wasps from gathering scale. Place grease bands round the trunks of trees and shrubs so the ants can’t climb up. A barrier of agapanthus – not the old-fashioned weedy varieties, nor when the trees or shrubs are young – also seems to cut down on the amount of scale ants carry up there.
But basically if you have a diverse range of insect-attracting and nectar-producing flowers, especially native ones, near your trees, the birds and other predators will keep the scale down for you. Parsnips, Queen Anne lace and other umbelliferae – named after their umbrella of white blooms – are wonderful pest-eater attractors though sadly, at our place, the parsnips are also excellent wombat attractors and they soon dig up the parsnips.
Thirty years ago I’d have been out with a notebook, keeping watch on what had munched through the crop of scale on the coffee bush. These days I’m happy that the garden looks after itself – many birds, many blooms and no major pests except late fruit fly, sorted out by ‘‘fruit sleeves’’ or anti-fruit fly netting and by plenty of chooks, wombats, wallabies et al to eat up any fallen fruit. Fruit fly-affected fruit drops prematurely and fruit fly don’t survive the journey down a wombat’s gullet.
And these days we grow the parsnips behind fences of reinforcing mesh where they can grow fat and even bloom, safe from the wombats.
This week I am:
- Watering the youngest plants in the garden, or the fruit trees that we most want to give some fruit.
- Trying to find the parsley among the weeds – I knew if I didn’t weed them last week they would vanish, though hopefully they’ll survive until they’re rescued;
- Watching the wombats’ annoyance as the new growth made by the hydrangeas brushes their noses as they push along the new paths they made during winter after we cut the hydrangeas back – it’s going to be a battle between the hydrangeas and the wombats as the bushes grow bigger during summer but I suspect the wombats will win … they usually do.
- Finally remembering to plant tomatoes and basil.
- Watching the garlic stems wither, which means they are almost ready to be picked – fresh garlic is mild and delicious, easy to peel before their skins become papery and excellent baked whole, skin and all.
- Not sure whether to rejoice or mourn the rufous whistler’s nest in the native lime just outside the dining room window. We have a voyeur’s view of the nest building, and hopefully baby birds, but equally we aren’t going to be able to pick the mid-summer native limes and the kids will make a bee line for them. We’ll have to hope the sight of tiny nestlings is enough to make up for the loss of breaking open the fruit to find the tiny globules bursting with juice.
Native Plant Sale
The Growing Friends group at the Australian National Botanic Gardens is holding their Spring Plant Sale on November 10 from 8.30am to 11.00am at the Banks Building car park.
Plants on sale from $6 each.
The plants are all propagated from material from the Gardens and all proceeds from the sale go to support the Gardens. The plant list and further information are available a week before the sale at http://www.friendsanbg.org.au/. You’ll find some real treasures there – and ones you know will grow beautifully in Canberra.
