Organic Sprays Against Greenhouse Pests and Diseases



Organic sprays against greenhouse pests

greenhouse pests and diseases The sprays listed here are generally of natural origin and should cause less persistent damage in the environment than many chemicals.

Nevertheless, take care as they are not harmless. They may kill beneficial insects and harm creatures other than the pest. Only use them as a last resort, and take as much care to make up the correct dilutions, and avoid spillage and spray drift, as you would with any chemical.

DO NOT:

  • Use a spray agent against pests other than those for which it is intended.
  • Spray plants when bees or other pollinating insects are working.
  • Spray after you have introduced biological controls into the greenhouse, unless you are sure that you are not harming them.
  • Spray in bright sunshine, as you could scorch plant leaves.
  • Spray when it is cold or damp, or when you cannot ventilate the greenhouse, as this will encourage fungal diseases.


Organic Spray

Effective Against

Cautions

Derris

Aphids, red spider mite, caterpillars. Kills mainly on contact, therefore spray directly on to the pest.

Poisonous to fish and harmful to some beneficial creatures including ladybirds.

Insecticide soap

Aphids, whitefly, red spider mite, scale insects. Spray directly on to the pest.

Can harm some beneficial creatures including ladybirds and their larvae. Can damage sensitive plants, eg. ferns, so do a small spot test before spraying the whole plant.

Pyrethrum

Aphids and small caterpillars.

Poisonous to fish. Harmful to some ladybirds. Many brands of pyrethrum also contain piperonyl butoxide, and these are now accepted as organic sprays.

Soft soap

Poisonous to fish. Harmful to some ladybirds. Many brands of pyrethrum also contain piperonyl butoxide, and these are now accepted as organic sprays.

None


Organic sprays against greenhouse diseases

Organic Spray

Effective Against

Cautions

Bicarbonate of soda

Powdery mildew, as both a preventive and a cure. Suggested dilution: 5g per litre with a wetter such as soft soap at 10g per litre.

This familiar household substance appears to be harmless to insects and plants, although badly mildewed leaves will turn black after they have been sprayed. Use not approved in the UK.


29. November 2010 by Dave Pinkney
Categories: Garden Management, Greenhouse Gardening, Pests and Diseases | Tags: , , | Comments Off on Organic Sprays Against Greenhouse Pests and Diseases

Follow

Get every new post delivered to your Inbox

Join other followers: