Gadenin日本語Get the appStart by deciding whether it is a pest at all
Peperomia attracts relatively few pests, and the great majority of plants brought back from the brink were suffering from wet compost, cold, or a draft rather than from an insect. Before you reach for a spray, work through the symptom and find out which category you are in, because the treatments are entirely different and treating the wrong one costs the plant weeks.
| Symptom | Most likely cause | Check this first |
|---|---|---|
| Stems soft and dark at soil level | Stem and root rot | Squeeze the base of the stem |
| Whole green leaves dropping off | Cold, or a sudden move | Night temperature near the window |
| White fluff in the leaf joints | Mealybugs | Look into the crown with a torch |
| Fine speckling, dull leaves, webbing | Spider mites | The undersides of the leaves |
| Small flies around the pot | Fungus gnats, from wet compost | How damp the surface is |
| Corky brown bumps under the leaves | Edema, a watering fault | Whether it scrapes off or not |
Stem and root rot, the one that actually kills
This is the problem that ends most peperomias. It begins in the roots, in compost that has stayed saturated, and travels up into the base of the stems. By the time the top of the plant looks wrong the damage below is already extensive, so respond on the first sign rather than waiting to be certain.
The reliable test is touch. Take the stem between finger and thumb right at the compost surface and squeeze gently. Firm is healthy. Any softness, any give, any darkening or sour smell means rot, and the plant needs cutting back immediately.
- Stop watering and take it out of the pot There is nothing to be gained by leaving it in wet compost while you think about it. Tip it out and look at the roots and the stem bases in daylight.
- Cut above every trace of damage Cut the stems until the cut face is uniformly firm and pale. A gray ring or a water soaked look means the rot is still ahead of the blade, so cut higher and check again.
- Take insurance cuttings Before you go further, take four or five healthy leaves or stem tips and set them up as cuttings. If the parent plant does not recover you have lost nothing.
- Repot small, in a gritty mix, and keep it dry Use the smallest pot the remaining roots will fit, a free draining mix, and one light watering. Then nothing for at least ten days, in bright shade and a warm room.
Fungicides do not fix this. The cause is compost that never dries, and until the watering and the pot size change, the rot returns.
Mealybugs and spider mites
Mealybugs are the pest most often found on peperomia, because the dense crown and the tight joints between leaf stalk and stem give them exactly the sheltered, dry place they prefer. They look like small specks of white cotton wool, and they are usually well established before they are noticed. Check the crown with a torch every time you water and you will catch them at the stage when a few minutes of work clears them.
Spider mites arrive in hot dry conditions, typically near a heater in winter. The first sign is a fine pale speckling across the leaf, and fine webbing between leaf and stem confirms it. On thick peperomia leaves the speckling is easy to mistake for natural marking, so hold a leaf up to the light: mite damage is a scatter of tiny transparent dots.
| Pest | Where it hides | Treatment |
|---|---|---|
| Mealybugs | Leaf joints, the crown, and on the roots | Dab each one with a cotton bud dipped in alcohol |
| Spider mites | Leaf undersides, near heat | Rinse the plant, then raise humidity and airflow |
| Fungus gnats | The top inch of wet compost | Let the surface dry hard, add a gritty top dressing |
| Scale insects | Along the stems, as flat brown discs | Scrape off by hand, then check weekly for a month |
Repeat any pest treatment three times at weekly intervals. Eggs survive a single treatment, and a population that looks cleared comes back in a fortnight.
Leaf drop, and the marks that are not pests
Sudden loss of whole green leaves is a shock response rather than a disease. The usual triggers are a drop in temperature, a move to a very different position, or a spell of cold combined with wet compost. The plant sheds leaves faster than it can regrow them, so identify the cause and hold conditions steady rather than intervening further.
Two common marks are not pests at all. Small corky brown bumps on the undersides of leaves are edema, caused by the plant taking up water faster than it can transpire it, and they follow a heavy watering in cool, still conditions; they are permanent on that leaf but harmless, and correcting the watering stops new ones. Dry, crisp brown edges with damp compost point at a heater or a draft rather than at thirst, and watering more in that situation adds root rot to the original problem.
Preventing the whole list
Nearly every problem above is prevented by the same three habits, which is unusual and worth taking advantage of. Water only when the compost is dry two inches down; keep the plant in a pot barely larger than its roots, in a gritty mix; and check the crown and leaf undersides once a fortnight while you water.
- Inspect while you water Make the fortnightly check part of watering rather than a separate task. Turn two or three leaves over and look into the crown with a torch. Thirty seconds catches mealybugs and mites at the easy stage.
- Quarantine anything new Keep a new plant away from the others for three weeks and check it twice a week. Most indoor pest outbreaks arrive on a new plant rather than appearing spontaneously.
- Keep air moving Still, stagnant air around a densely leaved plant favors both rot and mites. A little air movement, without a direct draft on the leaves, prevents more problems than any spray.
- Record what you find and when Note the date you first saw each problem, what you did and whether it worked. Pests recur at the same point each year, and a record of last winter's first mealybug lets you start checking a fortnight before it happens again.