Organic Garden Update: Dealing with the winged pests! (Guest post)

Last week I talked about that pesky ground dweller the slug, but airborne attacks on plants are also a problem in late spring. In this article I’m going to do a rogue’s gallery of some of the winged culprits.

Cabbage white butterflies are on the wing in late spring. Although these are a beautiful sight fluttering over gardens and fields, they can wreak havoc on brassicas such as cabbage, sprouts and broccoli. If they manage to lay their eggs on these plants, before long you will have a munching army of caterpillars crawling all over the place. The damage they can wreak is astounding- I once had some brassicas eaten down to the stalks by cabbage white caterpillars. The best thing to do to prevent this happening is net your plants early in the growing season with a fine mesh net.

Another pest that is foiled by a fine net over plants is wood pigeons. These are another pest that loves brassicas, but they are happy to eat other plants too. A tell-tale sign of pigeon damage is torn leaves. I’ve also seen gardeners put old CDs on sticks to deter pigeons- the flashes of light from the shiny surface as they move in the wind can frighten the birds away.

The last winged menaces in my rogue’s gallery today are aphids and whitefly. Aphids (also known as greenfly or blackfly) secrete a substance on plants that can encourage the growth of leaf mould, and they can also transmit plant diseases. Whiteflies have a similar modus operandi to aphids- secreting a substance that encourages mould- but this warmth-loving insect is more of a problem in greenhouses than outdoors.

It’s possible to just brush small numbers of aphids, aphid larvae and whitefly off your plants with a gloved hand- if you want to kill them off, you can brush them straight into a bucket of water filled with a solution of insectidal soap. If your plants are fairly robust, you can also blast aphids and whitefly off with a jet of water from a hose.

Another strategy is to encourage biological controls into your garden- that is, ladybirds! Happily, some of the plants that ladybirds like are edible plants including fennel, chives and dill (they eat the pollen from these plants). I really like this solution as it supports the biodiversity of your garden and can give you additional organic crops into the bargain. This is in contrast to conventional chemical insecticides, which kill all insects indiscriminately- beneficial insects and pests.

Another way to use plants to combat insects is to plant garlic around plants vulnerable to aphid attack- the aphids don’t like the smell (a drop of garlic oil smeared around the edge of pots can also do the trick). Neem oil is another method popular with organic gardeners. Mix with water and then use a spray bottle to apply the mixture to your plants. As long as you don’t spray it directly onto them, neem oil should be nontoxic to beneficial garden insects. Use the spray in moderation as needed, and wash all produce treated with neem oil well before eating.
Wishing you all happy (and pest free) gardening!             

Becky x   

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