Four Important Notes About Controlling Spider Mites Organically
Two-spotted spider mite is the most commonly found mite and is about the size of the pointed end of a pin. This pest weaves its web under leaves or on the growing tips of tender shoots. It damages leaves because it scrapes away at the leaf surface to eat. The more mites, the more damage you'll see on your plant.
Plants do not respond well to having colonies eating away at their leaves and do not grow very well when this happens.
You'll know you have this insect pest when you see 1) a very fine and small glistening web usually on the underside of leaves and 2) they typical mottling, discoloration or silvering of the leaves as the pests eat away at it.
Different plants will turn different colors and have a varied appearance because of their varied leaf structure. What is similar is the webbing and a “mottling” or pale leaf.
Check Your Plants
Check the plant by turning over the leaf. Examine the central rib of the leaf closely as it is sometime easier to see the webbing against the raised rib of the leaf. You might be able to see dust sized mites on this webbing but they will rarely be moving and move very slowly. You'll also see the webbing on the new tender, edible growth before the mites move to older leaves.
If you see a red spider mite moving then the odds are that this is a predator mite eating the spider mites. There will only be a few of these predators when compared to the large numbers of pests on the plant.
Treating Spider Mites
If there is a sizeable colony, then the easiest thing to do is spray the plant with insecticidal soap. This knocks the pest back quite nicely. You'll have to spray the underside of all leaves and into the crevices of the leaves as well as the growing tips to get a measure of control.
Repeat this spray every 7 days for a total of 3 applications to knock the population back. A single application will not kill off all these pests (been there – tried to kill these). Other organic products include rotenone and neem. Do read the label to see if a product is registered to control this problem.
Outdoor plants respond very well to compost tea to help them recover from the spider mites attack and will act to stimulate new growth and blooms. Indoor plants will respond to a feeding with fish emulsion.