Citrus: sweet and sour by Malcolm W. Campbell BA, MAIH, MIPPS.

If you live in a "Fruit fly" zone, then growing citrus will always be more demanding than for those who garden in free areas. There are a plethora of 'bugs' and insect vectors that nature has provided, that will either eat or spoil almost anything you are fortunate enough to be able to grow in your garden. Fortunately nature also provides bugs that eat bugs and birds that eat buds etc. It's probably easy for me to advocate an integrated pest management (IPM) program that doesn't rely very heavily on the use of toxic sprays, because I live in a "Fruit fly"- free zone in South Australia. I do however travel Australia regularly and I'm astonished at the trouble some gardeners will go to, to get a crop of fruit. In Darwin I've seen insect-proof cages erected over the orchard to keep the fruit-sucking moths away from the crop, not to mention the flying foxes and a host of other raiders that dwell in the jungle, hell-bent on a nightly sortie into the tropical fruit home garden.

The control measures for keeping citrus free of "Fruit fly", both the Queensland and the Western varieties, reads like a monthly spray commitment if you grow a range of cultivars, that all ripen at various times.

Because every state and territory has different problems and different registered products for control, it is not possible to present you with the definitive text of pest control in this tiny tome, so I recommend that you contact your local Primary Industries citrus expert for local advice. The Department of Agriculture New South Wales has an outstanding simple text of 19 pages, with coloured plates, of a range of citrus problems you may encounter in the home garden. Called "Citrus in the home garden... Pest, Diseases and Nutrient Disorders" it sells for $5.95 at booksellers as well as the Department offices. With the booklet, comes a most valuable Supplement that opens out to a chart and details the approved chemical controls under the Pesticide Act 1978 [NSW]. I might also mention that there are some national standards being prepared too, that may lead to uniform national legislation one day! If I sound cynical, it's only because the Senate enquiry into the need for this, first met three or four years ago and they have got about as far as recommending uniform labelling! So at that rate we may have uniform legislation and registration for the whole nation, early in the twenty first century. Imagine a situation, where because of the fact that each state has its own chemical registration system, we have seven sets of registered products, that are not the same, yet we have free trade between states and so a product banned in South Australia is freely available from Victoria and Queensland, by overnight courier. That is a fact.

Imagine the United States Department of Agriculture (USDA) allowing that in 51 states! Where it is really absurd locally, is that there is a chemical approved and registered to control... say "Bindii weed" in Queensland, that is banned in South Australia. Fancy that chemical working in Queensland, but not in South Australia or in West Australia. Is it that the Primary Industries Qld. are quite prepared to allow Queenslanders to be exposed to this chemical, banned for that use in other states, or is it that Queenslanders are tougher? Whatever the reasons or oversights, it doesn't make sense and needs to be addressed with uniform laws Australia-wide.

The average home gardener is not that well informed about levels of toxicity (the LD₅₀'s), which don't seem to appear on a label in any state or territory in Australia. The S levels that are printed on some labels are a joke, because a product like Roundup® has an S5 toxicity level on the label, because of the surfactant in the spray, rather than the active agent glyphosate. Monsanto's new Roundup Biactive® product for water weed control, carries the same S5 rating even though it has a totally new and very low toxicity surfactant in the product, that's been tested in the USA and proven to be safe enough to not even harm frogs, fish and crustacea! The only information that appears consistantly on Australian spray labels at present, is the with-holding period for a particular crop and the mixing precautions. Any other product information is either printed in a tiny 6 point font leaflet at the bottom of the package inside, where hopefully the manufacturer thinks you will forget to look, or you have to request the product information sheet from the distributor. Whatever you do, if you use chemicals, use them only according to the prescribed use on the label. That is your guarantee and your only course of redress.

In a nut shell, the greatest precautions need to be used when handling insecticides and miticides. Fungicides are generally less toxic to humans. Do not spray herbicides or weedkillers in the same spray gear as you use to spray insects and fungal problems. Some herbicide residues are very difficult to remove, given the poor design of most home garden spray equipment and the fact that the majority of sprayers are made from extruded poly products, that seem to collect residues!

If you are a keen organic gardener, there are certainly lots of options for control available to you. There are insects available commercially that will assist in the control of scale on your citrus. These are available from Bugs for Bugs, 28 Orton Street, Mundubbera Qld 4626 and from Biological Services, PO Box 501, Loxton SA 5333 and there are sure to be others in your area. Ask your local Primary Industries officer or the Botanic Gardens Information folk.

The old mineral oils that were used on citrus crops to control scale, have in recent times be replaced by outstanding new synthetic oils, that do not damage the foliage and break down rapidly, but still offer good protection. One such product in Ampol PestOil™, but I'm sure it will be followed by lots of other copy-cat products soon. I've found PestOil™ to be effective against Aphids and Scale and I suspect some Mites too, but that's an off-label use, that cannot be condoned at present.

A word of caution on the use of organic compounds... some of them, such as the saponins are actually more toxic than the chemical equivalent to rid your garden of the same pest. Use protective gear for all spray applications, organic and chemical.

After all the concern for clean, pest free citrus crops, I have to concede that I've seen many fine citrus trees all over Australia, that have nothing done to then annually and they still produce acceptable crops. I hope you can do the same. If you really get serious about growing any of these citrus, you will need to read up a bit more and ask a lot more questions, but for the time being I hope this small tome has added to your interest in gardening and in particular assisted you to grow one of our best home garden crops in Australia... the sweet and sour citrus.