Gadenin日本語Get the appFind it early by looking underneath
Indoor ficus pests are almost invisible until they are numerous, because every one of them lives on the underside of the leaf and in the joints where a leaf meets the stem. By the time you notice something on the upper surface, the population has been building for weeks.
Turn over five or six leaves whenever you water. It takes half a minute and it is the difference between wiping off a dozen insects and treating an infested plant for two months.
| What you see | Likely cause | First thing to do |
|---|---|---|
| Sticky shiny film on leaves or floor | Scale or mealybugs above it | Look on the stems and leaf undersides directly above |
| Fine webbing in the leaf joints | Spider mites | Raise the humidity and wash the plant |
| Brown limpet-like bumps on stems | Scale insects | Scrape them off by hand |
| White fluff in the leaf axils | Mealybugs | Dab each one with alcohol on a cotton bud |
| Black sooty coating on upper leaves | Mold growing on pest honeydew | Find and treat the pest, then wash the leaves |
| Small flies around the pot | Fungus gnats from wet compost | Let the compost dry out properly |
A sticky floor under a plant is a diagnosis, not a mess. It is honeydew excreted by sap-feeding insects, and it means you have a live population above it right now.
Scale insects
Scale is the classic ficus pest and the one people miss for longest, because a mature scale looks exactly like a small brown bump on the bark rather than an animal. They sit still under a waxy shell, feed on sap, and drip honeydew that makes everything below sticky.
The shell is why contact sprays work poorly. Physical removal is more effective than any spray, and it is the treatment to start with.
- Scrape them off Push each bump off with a thumbnail or the back of a knife. They do not reattach. Do the stems, the leaf undersides and especially the leaf joints, and check the pot rim too.
- Wipe with soapy water Wash the whole plant with a soft cloth and a weak solution of dish soap in water. This removes the crawling young stage, which is the only stage that moves and spreads.
- Repeat every week for a month Eggs hatch under the old shells over several weeks. One treatment always fails. Four weekly treatments usually clears it.
- Cut out the worst branches A branch encrusted with scale is faster to remove than to clean. Take it off at the collar and bag it immediately.
Isolate an affected plant from the others while you treat it. Scale crawlers move between touching leaves and will colonise a neighboring plant within days.
Spider mites and dry air
Spider mites are too small to see clearly and you find them by their effects: a faint pale stippling across the leaf, a dull grayish cast to the foliage, and eventually fine webbing in the leaf joints. They multiply explosively in hot dry air, which is exactly what a heated room in winter provides.
Humidity is both the prevention and half the cure. A plant misted regularly on the leaf undersides, or standing on a tray of damp pebbles, rarely gets a serious infestation.
- Wash the plant thoroughly Take it to a shower or use a spray bottle and wash every leaf underside. Physical removal knocks the population down immediately, more than any spray does.
- Mist the undersides, not the tops Mites live under the leaf. Spraying the upper surface achieves nothing. Aim upwards from below.
- Treat weekly for three weeks Eggs are unaffected by washing and hatch within days. Three weekly repeats catches each new generation before it breeds.
- Move it away from the heat source A plant in the dry blast of a radiator or vent will be reinfested no matter how well you treat it. Relocating it is part of the treatment.
Root rot and the problems that come from the pot
More indoor ficus die from wet compost than from every pest combined. The symptoms are deceptive: leaves yellow and drop, and the plant looks exactly like it is thirsty, so the usual response makes it worse.
When a plant is declining and the compost is damp, take it out of the pot and look at the roots. Healthy ficus roots are firm and pale. Rotted roots are brown or black, soft, and pull apart between your fingers, and the compost smells sour.
- Cut away everything soft Trim back to firm pale root with clean pruners. Leaving dead root in the pot keeps the rot spreading.
- Repot into fresh, open mix Discard the old compost entirely. Use a mix with plenty of perlite and bark, and choose a pot that is snug rather than generous.
- Reduce the top to match If you removed a third of the roots, remove roughly a third of the leaves. The remaining roots cannot supply a full crown.
- Water sparingly until it recovers Keep it just damp and warm, out of direct sun, and do not feed for two months. Recovery is slow and the first sign of it is a new leaf, not a recovered old one.
Fungus gnats are a symptom rather than a disease. Small black flies around the pot mean the compost surface is staying wet, and they disappear once you let the top two inches dry properly between waterings.
Leaf problems that are not pests at all
A great many ficus complaints are cultural rather than biological, and reaching for a spray when the actual problem is a draft wastes time and stresses the plant further. Check these before you treat for anything.
| Symptom | Cause | Fix |
|---|---|---|
| Green leaves falling with no yellowing | Cold draft or a sudden move | Block the draft, then leave it alone |
| Brown crisp edges on healthy leaves | Dry air or salt build-up | Raise humidity, flush the pot with plain water |
| Large brown patches in the leaf blade | Sunburn, or cold water on the leaf | Filter the direct sun, water at the roots only |
| New leaves small and pale | Too little light | Move it to the brightest window you have |
| Lower leaves yellow, plant otherwise fine | Normal turnover, or overwatering | Check the compost before deciding |
Record the date, the symptom and what you changed each time something goes wrong. Ficus problems repeat annually, usually as the heating goes on or off, and a note from last winter will identify this winter's problem in seconds.
Knowing when to stop trying
A ficus with a firm stem and even one healthy leaf is worth persevering with, and plants that look finished do come back over a season. Warmth, bright light, careful watering and patience will recover most of them.
What is not recoverable is a stem that has gone soft and brown at the base, because the rot has reached the trunk and nothing above it can be supplied. In that case take any firm green upper section as a cutting and start again from it rather than nursing the parent through another six months.