Gardening Vivian | 01 Jul 2011 02:39 pm

Rose Bushes and Greenfly

Growing roses has its rewards: the perfumes on a warm summer evening, the display of color which rather than being gaudy or garish is so elegantly tasteful, or the single red rose that you cut for your special someone.

Ah yes, that single red rose. The one that appears to have developed a life of its own ‘cos it’s moving!
I have a closer look and there they are; millions of them – aphids!

Little green critters that, individually, can produce 50 offspring, or to put it another way, in a month that solitary one, will beget six million descendents, and they’re all on my roses.

Insects in the garden can be beneficial, but not greenfly and certainly not to my pride and joy. I realize that greenfly are the natural prey of some of the larger insects in my garden. Insects like the lacewings, the hoverflies, wasps and the ladybugs. I also appreciate that some of our favorite garden birds will have a bumper harvest of their own when it comes to feasting on these varmints, an opportunity to maybe raise several families, but not in time to save my roses.

As in all areas of nature, the predators are always playing catch-up because they’ll only increase their numbers when there’s sufficient prey, as such these greenfly will have a head start, allowing them to create havoc before their natural predators can rally their forces.

Aphids infest the softest parts of the roses, often the tips of the canes, the undersides of new leaves and the rose flowers themselves. These aphids can spread disease from rose to rose simply by penetrating the new growth and sucking the sap, and because they’re not too meticulous when it comes to personal hygiene, they’ve probably picked up some nasties from my neighbor’s garden. Aphids secrete a sticky liquid called honeydew when they eat, and this can easily lead to sooty mold – a black fungal disease that will further weaken our roses.

Should this happen to you next year, rather than resorting to an insecticide, if you’re not too squeamish, you can squeeze them between thumb and forefinger or, failing that, you can flush them off by playing a water hose on them. Obviously, this is best done before their numbers become uncontrollable.

Another line of attack is to encourage these predatory insects by companion planting the roses with tagetes, calendula, poached egg plant and morning glory nearby. Had I planted these before the aphids arrived things might have been different.

If you already know that aphids breathe through their skin, then you’ll also know that if you spray them with dilute washing up liquid, this will clog their skin and they’ll suffocate. Another friendly way of controlling them is to use a potassium-salt, insecticidal soap which you can get from your local garden center. How about making your own? I’ve heard that oxalic acid from stewed rhubarb leaves can be quite effective too, but I’m not sure about the effects on the beneficial bugs that you can attract.

I realize now (a little late) the best line of defense, is to organize myself at the beginning of next growing season and be prepared for the worst.

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