Dracaena Pests and Problems: Spider Mites, Mealybugs and Rot

What actually turns up

Dracaena has a short list of real problems, and most of what people bring to it as pest damage is water quality or cold. Rule those out first, then work through this list. The two pests that genuinely recur indoors are spider mites and mealybugs, and both are far easier to deal with in the first fortnight than in the second month.

Check the undersides and the leaf joints, not the top surfaces. Every one of these starts somewhere you cannot see from a standing position.

Spider mites

Hot, dry, still air is exactly what spider mites want, so a dracaena next to a radiator in winter is where they almost always appear. They are barely visible individually; what you notice first is a fine pale stippling across the leaf, and by the time there is obvious webbing the population is already large.

The confirming test is to hold a sheet of white paper under a leaf and tap it sharply. Specks that fall and then walk are mites. Specks that stay put are dust.

1. Wash the plant down Take it to a shower or outside and spray the undersides of every leaf hard with tepid water. This alone removes most of the population, and doing it weekly for a month usually finishes the job.
2. Raise the humidity around it Mites struggle in humid air. Group the plant with others and move it out of the direct heat, which is what let them in.
3. Treat if washing is not enough Insecticidal soap or a horticultural oil, sprayed to cover the undersides completely, works but only on contact. Repeat every five to seven days for three applications to catch newly hatched mites.
4. Isolate it Move the plant away from the others until you have had two clean weeks. Mites walk from plant to plant where leaves touch.

Mealybugs and scale

Mealybugs sit in the tight joint where a leaf wraps the cane, protected by a waxy white coat that repels sprayed water. They are slow moving and easy to miss until the numbers climb, and then the plant becomes sticky with honeydew and a black sooty mold grows on top of it.

Scale insects look like small brown bumps stuck to the leaf underside and do not move at all, which is why people take them for a blemish. Both are handled the same way and both need persistence: one treatment never clears them.

1. Dab each one with alcohol A cotton bud dipped in rubbing alcohol dissolves the waxy coat and kills the insect on contact. Work through every leaf joint methodically, including ones that look clean.
2. Scrape scale off Adult scale can be pushed off with a thumbnail or a blunt knife. Once removed they do not come back to the same spot, but their crawlers will already be elsewhere on the plant.
3. Repeat every week Eggs and crawlers survive any contact treatment. Go over the plant weekly for at least a month and inspect for a further month before you call it clear.
4. Wash off the honeydew Wipe the sticky residue and any sooty mold off the leaves with a damp cloth. The mold does not attack the plant but it blocks light.

Check the pot rim and the compost surface too. Mealybugs shelter under the rim and in the top of the compost, which is why plants get reinfested from what looks like a clean plant.

Rot, and when to give up on a cane

Stem rot on a dracaena starts at the base and works up the inside of the cane. The outward sign is a cane that gives when you squeeze it, sometimes with a sour smell, and by then the roots are usually gone as well. This is the one problem that kills quickly.

The decision is whether there is firm tissue left. Squeeze the cane at intervals from the base upward until it feels hard, and cut two inches (5 cm) above the point where it firms up. If the cane is soft all the way to the leaves, the plant cannot be saved as it stands, but the top may still root if it is firm.

1. Take it out of the pot and look Firm pale roots mean the rot is confined to the stem. Black, soft roots that pull away between your fingers mean the root system has gone.
2. Cut back to clean tissue The inside of a cut cane should be white or cream. Brown, water soaked tissue means keep cutting higher until it is clean.
3. Root the healthy top If the head and the top of the cane are firm, take it as a cutting, let the cut dry a day, and root it in fresh free draining compost. This is usually the plant you keep.
4. Do not reuse the compost Throw the old compost away and wash the pot before you use it again. Rot organisms persist in both.

Fungus gnats and leaf spot

Small black flies rising from the pot are fungus gnats, and they breed in permanently damp compost. They do almost nothing to a mature dracaena, but they are a signal that the top of the pot never dries, which is a real problem. Letting the top inch (2 cm) dry between waterings breaks their cycle within a few weeks, and a half inch of grit on the surface stops the adults laying.

Round tan spots with a darker margin are a fungal leaf spot, and they follow from water sitting in the leaf joints in a still, cool room. Remove the worst affected leaves, improve the airflow, water the compost rather than the foliage, and it stops spreading.

Keep a note of the month a pest appeared and what cleared it. Spider mites in particular return in the same weeks each year, and knowing that lets you start washing the leaves before you can see them.

Toxicity, and what to keep away from

Dracaena leaves contain saponins and are toxic to cats and dogs, causing vomiting, drooling and, in cats, dilated pupils. A tall plant with leaves at nose height for a curious animal is a genuine risk, and the fallen leaves are as much of a problem as the ones on the plant.

The sap is a mild skin irritant for people and will stain fabric. Wear gloves when you cut, sweep up dropped leaves promptly, and stand the plant where a cat cannot use the cane as a scratching post.