Articles Posted in the Garden category

Aphids, ants and me

January 20, 2009
Posted in Garden

Aphids and an ant on a bean plant

A herd of aphids and an ant on a bean plant

Freshly picked beans taste different from those you buy in the supermarket, even organic ones. They’re sweet and have a less fibrous texture so they’re absolutely delicious raw.

Both my gardening books say that green beans are easy to grow, and until recently I would have agreed with them wholeheartedly. Once they start to produce, beans just seem to go on and on, every morning you can go out and pick a handful, it’s very gratifying. It’s also easy to tell when they’re ready to be picked (the same cannot be said for onions, potatoes and butternuts).

There is a catch, though: they attract aphids, tiny little black insects that accumulate along the stems, under the leaves, in fact, all over the place. They collect in clumps that look like crusty black scabs. I came back from holiday, took one look at my beans and panicked.

I immediately consulted the internet for organic aphid-control methods and found do-it-yourself recipes that involved things like crushed raw garlic and “soft soap” – which, according to the Soil Association, contains fatty acid potassium salt, which is derived from bone material and palm oil.

So off I went to the nursery to find some of this soft soap, but I ended up getting Ludwig’s Organic Insecticide (made by Kirchhoffs, R69,95) because the guy at the nursery said it’s much easier than trying to make my own spray, and it’s authorised for use in organic agriculture by Ecocert. It contains canola oil, which is said to “kill small bodied insects on contact by means of suffocation”, pyrethrum which can kill larger bodied insects (and aren’t mosquito coils made of it?) and garlic because this apparently puts insects off from landing on the plants. Boy, does it contain garlic, enough to make your eyes water.

Anyway, a word of advice to anyone who decides to spray aphids. Wear rubber gloves, wrap old tea towels around your wrists to stop the stuff from running down your arms; stand upwind when you spray; and start from the bottom of the plants and work upwards. You have to spray the insecticide directly onto the insects and, because the little buggers hide under the leaves and in hard to reach bits, it’s a messy business. If you have a lot of them like I did, it’s also not a quick job.

The stuff worked, though, the aphids seemed to shrivel up and some, but not all of them, dropped off. But a week later I noticed ants running up and down the bean plants, so I took a closer look and found that the aphids had returned.

Apparently ants “farm” aphids, moving them to “tender spots” on a plant and milking them for honeydew. As charming as this little ant ecosystem may seem in theory, beans with aphids on them aren’t very appetising.

I don’t really want to get into a situation where I have to spray insecticide once a week and I don’t want to put off  bees and ladybirds from visiting my plants. The books say that ladybirds eat aphids so they are a useful natural control method – alas I have seen only one ladybird on my beans so far.

For the past three days I have been following the advice of the organic gardening book I got for Christmas which says: “Use the jet from a garden hose to knock aphids and other pests off plants: some may return but many will not”. After all, it says, the aim of organic gardening is to control pests not eliminate them and the spraying of pesticides should be a last resort. (Organic Garden Basics, by Bob Flowerdew, Hamlyn, London, 2008)

A strong jet of water applied directly does seem to knock them off the plant, but the aphids and their little ant farmers recover quickly – you can knock them off in the evening and by the morning they’ll be back again – so you have to keep watch for them and not let them get the better of you.

I think I’m managing to keep one step ahead, but it’s been only three days, so I’m not ruling out the possibility of having to spray again.