Organic standards insist on a chemical‐free journey for every plant, from seed to harvest. Farmers and home growers are ingenious in their methods for achieving this – but sometimes your cabbages will be so caterpillar‐infested that you’re desperate for help. What are permitted pesticides for your organic vegetables?
Before you resort to pesticides, ensure that you are incorporating the key organic guidelines. CROP ROTATION is an important way to keep your soil relatively free from pests: confuse the caterpillars by moving your cabbage patch across the plot from one season to the next. It may seem unlikely, but TIMING can play an important role in preventing pests, too: for example, early‐sown carrots will avoid first‐generation carrot fly.
PHYSICAL BARRIERS are great for protecting your cabbages against caterpillars – as butterflies can’t get close enough to lay their eggs in the leaves. A barrier will also protect your carrots against carrot fly, which tend to fly close to the ground. Finally, COMPANION PLANTING is a useful technique: choose the plants that attract the right types of insect, and you’ll be able to encourage a population of ‘helpful’ insects on your patch. Chemical pesticides may have historically diminished the population of these insects: it’s time to bring them back. A SMALL POND is another great idea, since frogs and toads will pick slugs and snails from your crops – causing no trouble to you in the meantime.
Biological controls are quite new to the market. You may have heard of Nematodes ‐ tiny parasites that eliminate your slug population. These and other biological controls are actually living micro‐organisms. These micro‐organisms are the natural enemies of different pests, for example: Bacillus Thuringiensis is a form of bacteria that eliminates caterpillars, parasitic nematodes destroy slugs and snails, and predatory mites attack red spider mite. They are despatched to you (humanely) in sealed packets, and should be stored in the fridge until you are ready to apply (as soon as you can). The treatment is applied to the soil or directly to the affected plants; nematodes are added to a full watering‐can and watered in to the soil, while parasitic mites are sprinkled onto leaves.
Chemical sprays are generally frowned upon in organic gardening: research has shown that sprays used by farmers remain on crops and can be found in our bodies. Organic growers like the notion of being able to control what’s in the food that they will eventually eat. But some chemicals are permitted for organic use.
The main options are derris, sulphur, copper, and soft soap sprays. If you choose to buy these, check that the products are approved for organic gardening. They are permitted partly because they break down very quickly, so traces won’t be present (or toxic) in the harvested crop. They won’t affect other animals or birds that encounter them (although they may harm some insects – always check the labelling). Permitted chemicals are usually less permanent than the non‐organic alternatives, so will have to be reapplied more often. Just like all chemicals, they can be overused, which causes pests to build up a natural resistance – and weakens the chemical’s effectiveness. If you choose to use any chemicals, organic or otherwise, you should take care to spray your targeted area only: avoid water and take care not to let the sprays drift onto a neighbour’s vegetable patch.