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Helping plants call for reinforcements

When a plant is damaged by an insect pest, such as a caterpillar, it does not just sit there – the wounding leads to the production of volatile chemicals. These have three functions:

1) they ‘switch on’ chemical defences in the damaged plant;

2) they send a signal to other plants that damage is occurring in their immediate environment; and

3) the same signal tells beneficial insects such as ladybirds that food for them (i.e. the pest) is available to them upwind.

Of the chemicals involved, a key one is methyl salicylate which, incidentally, is a key ingredient of some products that we use to ease muscle pain, such as after sporting activities. Use the sachet provided to attach to a tree or a stick in your vegetable plot and observe good insects being attracted to that location.

Attaching the sachet

Remove the sachet from the foil pack and attach it to the trunk of a tree or to a wooden stake in your vegetable patch. Fasten it firmly so that it does not blow around in the wind.

Project 1

After a day or so, examine the sachet to see if any beneficial insects, such as ladybirds, lace wings etc., have landed near it.

Project 2

Look at the vegetables nearest to the sachet, especially downwind and see if you can find beneficial insects on the leaves and of what types.

How Does Your Garden Grow Kit

This unique kit is based on research carried out in the Bio-Protection Research Centre at Lincoln University in association with the BHU Organics Trust and Kings Seeds. The kit will help you to discover a number of important things such as the acidity of your soil (slightly acid for potatoes, slightly alkaline for brassicas) and how to attract bees to your crops and ladybirds to eat your pests.

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