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What Do Organic Growers Do About Red Spider Mite?
If you see pale yellow dots on the underside of the leaves of your cucumbers, peppers, marrows or strawberries, or a thin web on the leaves and stems of your prize roses, then probably you are being visited by the red spider mite. These tiny sap-sucking pests, which thrive in hot dry weather, can sometimes be difficult to see with the naked eye. They can be particularly devastating to young plants, especially peppers.
Humidity
If the mites are regular visitors to your garden or greenhouse, then a simple precaution during periods of warm dry weather is to keep the area moist around susceptible plants. This will raise the humidity making the area less attractive to the mite.
Inter-cropping
Red spider mites have no interest in tomatoes but they love cucumbers, turning the leaves yellow and drastically reducing the yield. Most gardening books frown on the idea of growing cucumbers and tomatoes close together because of their different humidity requirements. However, gardeners forced to do this because of lack of space in the greenhouse or garden find that their cucumbers often escape the attention of the pest. Growing a wide variety of plants together, such as tomatoes, peppers, cucumbers or melons seems to reduce rather than increase pest troubles.
Inspection
Check your plants regularly for pests so that you notice the first arrivals when they come. If you catch them in time, there should be no need to use any insecticide. Spending a few minutes taking them off your plants or squeezing them between your fingers should be sufficient to control them. Of course with the tiny red spider mite this can be difficult. Especially in summer when, despite their name, the mites are green!
Derris
If the mite population reaches epidemic proportions then you might have to use derris, despite the fact that it will destroy the eggs and larvae of the ladybird. It can be bought as a liquid or a powder. If you use the liquid form, then it's best not to apply it during bright sunshine. Water resting on the leaves of plants can act as a magnifying glass for the sun, resulting in burnt leaves.
There is a biological control for red spider mite, another mite called Phytoseiulus persimilis. Organic gardeners with large numbers of plants generally find predator controls quicker and easier to apply than sprays or powders.
Water
As with most small pests even spraying pure water on them will reduce their numbers. If you would feel foolish spraying just water then you might be interested to know that in Nigeria where the mite is a huge problem, gardeners add one cup of white flour and half a cup of sour milk to a gallon of water as a cure. I understand the plants turn white for a while until the flour falls off!
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