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Good Gardening: Organic pesticides

A chard leaf with pest damage.
John Fischer
/
KLCC
Spraying spinosad, an organic pesticide, on beet and chard leaves will kill the leaf miners inside the leaf.

Hi All, Lane County Extension Service Master Gardener John Fischer here with KLCC's Good Gardening.

I am an organic gardener. Put simply, that means I don't use any synthetic chemicals on the food I eat - or on the flowers I pick.

It doesn't mean I don't fight pests with a spray bottle at times. Safer's soap for aphids, BT for cabbage moths, and Kaolin clay for apple worms - coddling moths- are part of my spring and summer regimen.

Most organic insecticides must contact the pest to be effective - you have to spray it right on the bug. Many chemical pesticides are systemic, not topical. The pesticide makes the entire plant - roots, leaves, flowers- the parts you eat- poisonous - highly toxic to insects, ideally, less so to us. Those commercial pesticides are very effective, but it seems wrong - to me- to eat something full of poison - or to give a friend poison filled flowers. Pesticide levels on imported flowers are almost completely unregulated because flowers are not a consumable product.

But there is a relatively new, and increasingly popular organic pesticide - spinosad- that can get through leaf membranes, and targets leaf miners, thrips, cabbage worms, flea beetles, and other pests. Spinosad in a natural substance produced by soil bacterium, and has been around used 25 years, but has gained popularity among home gardeners in the last decade.

Spraying it on beet and chard leaves will kill the leaf miners inside the leaf - nothing else organic is very effective. Don't spray it when bees are active - in can kill them, but unlike the villainous neonicotinoids, once it has dried on the leaves, it won't affect our honey making friends. Spinosad is commonly used on organic apples.

A small bottle goes a long way. Share some with a friend, and you may get some nice beets in return.

I'm John Fischer with Good Gardening.

John Fischer is a Master Gardener and Master Recycler and the host of KLCC's Good Gardening and Living Less Unsustainably.
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