Jade Plants and Brown Spots

Scale Insects

• Scale insects look like small, brown domes or bumps attached to the leaves and stems. They are actually small, soft-bodied insects sheltering under a hard, waxy shell. Scales are between 1/16 and 1/2 inch in diameter and tend to cluster on the undersides of the leaves and on the stems. They are immobile but can be scraped off with a fingernail.

Treatment

• Scrape off as many of the scale insects as possible with your fingers. Dab any inaccessible scales with a paintbrush or cotton swab dipped in rubbing alcohol. Check the plant every day for new scales. Dead scale insects will not fall off the plant but are hollow and brittle when squished. Live scale insects contain body juices.

Chemical Treatment

• Treat severe or persistent infestations with a spray containing horticultural oil or an insecticide. Choose a spray formulated for houseplants. Test any spray on a small branch as jades are sensitive to many chemicals. If no damage occurs within 48 hours, apply to the whole plant. Respray the plant every week until no new scales appear. Avoid insecticidal soaps as they damage jade plant leaves.

Prevention

• Isolate an infested plant to prevent the scales from spreading to other houseplants. Do not move your jade plant outside during the summer months if it is prone to scale infestation.

Oedema

• Oedema, or edema, causes small blisters on jade plant leaves, followed by corky brown spots. Oedema happens when plants absorb more water through their roots than they lose through their leaves. Reduce the amount of water you give a jade plant with signs of oedema. Move it to a brighter spot in the home. Existing spots are permanent, but no new ones will appear. Jade plants need less water during the winter because of lower temperatures and light levels.