Every new season brings a parade of irate customers into the garden centre clutching little baggies, jars and plastic containers full of infested and diseased plant bits. By far the most common insect we see is aphids. Green aphids, black aphids, red, bronze and purple aphids – they come in many colours! I thought I’d share my favourite method to control aphids with you now, before these common insects (sometimes called plant lice) really get going in your garden.
When temperatures are warm enough, the first generation of aphids hatch out – all female and ready to reproduce at a truly terrifying rate. The result of this fecundity is a population explosion that puts bunnies to shame…
Most years this occurs during June around here, but a mild spring will invoke earlier invasions, and of course the aphids have been in your trees, feeding and reproducing for a few weeks before the damage is evident.
Eventually you notice that the tips of the branches look odd, the leaves all curled up and distorted, and when you unfurl one of these leaves there are about a million little critters on the underside – disgusting! You may find a sticky substance coating the leaves (and your car, if you park underneath an infested tree) and a parade of ants marching up and down the limbs of your tree.
The sticky stuff is called honeydew, it’s actually excretions from the aphids and it’s sweet and delicious if you’re an ant – so that’s what they’re doing. Sometimes ants will “farm” aphids, carrying them up into a plant to provide a source of honeydew, clever little buggers they are!
Aphids are very soft-bodied, and if you’re not squeamish you can control the ones within reach by squashing them between your fingers (gloves makes this practice slightly less revolting).
If you have an aphid infestation on a plant that’s too large for this method you can spray the tree with any number of insecticides – aphids are relatively easy to kill, but I don’t like to use any pesticides if I can possibly avoid them, and I’ve discovered a method that works well for me.
I drag my hose out to the infested tree or shrub, with my old brass nozzle attached, crank up the pressure and slay the dastardly aphids with plain water! Some are crushed, some simply blown off the plant, and I like to think that a few are drowned! I have ample water pressure to reach even the topmost branches of my trees (of course in my new garden none are too tall yet). Three or four days later I repeat the process, and I keep on doing this until I no longer need to.
How do I know when I can stop? Well, that’s the best part of spraying with water! When you use a pesticide, even an organic pesticide, you leave a residue on your plant. That residue deters insects, even the good ones, so any remaining aphids (the extra-tough ones that survive your pesticide or the ones that hatch out after you spray) will flourish unimpeded and produce a second wave of infestation unless you spray more pesticides. This is why most pesticides recommend that you re-apply every ten days or so.
I am NOT doing that all summer! It’s way too much work, not to mention costly, and you might eventually damage the plant you’re trying to protect, depending on which pesticide you’re using.
Spraying with plain old water, on the other hand, doesn’t leave any smelly residue, so beneficial insects (aphid eaters) will eventually discover the little colony on your tree, a buffet for them! Usually after I spray three or four times I notice that while I’m spraying the aphids off I can see a lot of other insect action. The aphid eaters don’t much like the high pressure water either so they play dodgeball with my watery cannon, and I can clearly see them! Ladybugs, lacewings, wasps and various other insects are feasting on my plant pests.
When I see lots of these good bugs I know that I can stop spraying. Please note that this post is named How to Control Aphids, not How to Eradicate Aphids! I certainly won’t get rid of all the aphids, but a balance is reached where the plant can cope without showing noticeable signs of damage, and that’s all good. Hmmm, I should probably write another insect-related post; It’s Impossible (and counterproductive) to Rid your Garden of Insects so STOP TRYING!