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The characteristic failure is a plant that looks perfectly well one week and collapses the next. Lift the mat gently and you find the stem at ground level has gone brown, soft and slightly translucent, and the roots come away with no resistance. That is stem and crown rot, caused by fungi that get into soft succulent tissue whenever it stays wet and cool. It is not a disease you treat; it is a condition you avoid.
The three things that cause it are heavy or improved soil, water sitting in the crown, and a spell of cool damp weather on soft, well-fed growth. You control the first two directly. Plant into gritty free-draining ground, set the crown slightly proud of the surface, gravel-mulch around the plant rather than composting, and water at the soil in the morning so the plant is dry within the hour.
Once a plant has gone soft at the base there is no recovery. Pull it out with the surrounding inch or two of soil, and do it the day you notice, because in a close-planted mat the fungus moves straight into the neighbors. Leave the gap open rather than filling it; sun and moving air on that patch of soil are the best follow-up you can give.
Slugs and snails on young plants
Slugs and snails find the fat juicy leaves of a young Livingstone daisy extremely attractive, and they will strip a newly planted patch in a single damp night. The damage is unmistakable: whole seedlings gone at ground level, ragged holes chewed through the thick leaves, and silvery trails across the surrounding soil in the morning.
The vulnerable period is short. From planting out until the plants have spread and hardened, roughly the first three weeks, they need protecting; after that the mat is tough enough and the ground around it usually too dry and gritty to be comfortable for slugs. Check by torchlight on the first damp evenings after planting, since hand-picking at night in that narrow window is more effective than anything else.
A ring of coarse grit or sharp sand around each plant helps and suits the plant anyway. Keep the ground bare and free of leaf litter, boards and pot rims where slugs shelter during the day. If you use pellets, use them sparingly and only in that first three-week window.
| Symptom | Cause | Action |
|---|---|---|
| Sudden collapse, brown soft stem at soil level | Stem and crown rot | Remove the plant and soil at once; improve drainage; stop overhead watering |
| Seedlings vanish overnight, silvery trails | Slugs or snails | Hand-pick after dark; grit ring; clear shelter nearby |
| Ragged holes chewed in thick leaves | Slugs or snails | As above; damage stops once the mat hardens |
| Sticky growing tips, distorted buds, small green insects | Aphids | Wash off with a jet of water on a warm morning; repeat in three days |
| Fine webbing, dull stippled leaves in a hot dry spell | Red spider mite, usually under cover | Increase air movement; move outdoors; badly hit plants are not worth keeping |
| Gray fuzz on dead petals spreading to leaves | Gray mold in a wet spell | Remove affected growth on a dry day; open the planting up |
| Seedlings topple with a pinched stem in the tray | Damping off | Sow thinly, water from below, improve ventilation; discard the tray |
| Leaves soft and wrinkled, plant still firm at base | Simple thirst, not disease | Water thoroughly once and let it dry out again |
Aphids and the minor pests
Aphids turn up on the soft growing tips and unopened buds, usually in a warm still spell in early summer. You will notice the tips looking sticky and the buds slightly distorted before you notice the insects themselves. A firm jet of water on a warm morning removes most of them, and a repeat three days later removes the rest. The plant dries quickly enough in a sunny position for this to be safe.
Red spider mite is only a problem on plants kept under cover in a hot dry spring, and it shows as dull stippled leaves with fine webbing in the leaf joints. The answer is to get the plant outdoors into moving air as soon as the weather allows rather than to treat it. Plants that are badly infested are not worth carrying on with, since replacements are trivially easy to raise from seed.
Gray mold appears on the dead petals after a wet spell and can spread from there into the leaves. Pick off the affected growth on a dry day and thin the planting if it has closed up. Both of these are weather problems dressed up as pest problems, and both go away when the sun returns.
Do not reach for a fungicide when a plant collapses. By the time you see the symptom the tissue is already dead, and the useful response is to remove the plant, open up the planting and correct the drainage. Fungicides do nothing for rot that has already taken hold.
Damping off in the seed tray
The seedlings are fine and thread-like, and they are highly susceptible to damping off, which shows as a seedling toppling over with a pinched, water-soaked stem right at compost level. In a warm, still, crowded tray it can move through a whole sowing in two or three days.
Prevention is entirely mechanical. Sow far more thinly than feels sensible, use a gritty free-draining seed mix rather than a rich one, water from below and let the surface dry between waterings, and keep air moving over the tray. A thin layer of fine grit or vermiculite over the surface keeps the stems dry at the point where the fungus attacks.
Once damping off has started in a tray it will usually take the rest, and the practical response is to discard that sowing and start again in clean trays with fresh mix. Livingstone daisy germinates fast and the season is long enough that a fresh sowing loses you very little.
Knowing when to give up, and what to record
Because this is an annual raised easily from seed, the economics of rescuing a sick plant are poor. A plant that is soft at the base, or one that has been stripped by slugs down to a stub, should come out. A plant that is merely thin and sprawling can be sheared back and will recover. That is the whole of the decision.
Keep a short note of every loss: the date, the position, and the weather in the preceding week. Almost every entry will fall in a cool wet spell, and the pattern that emerges will tell you which parts of your garden hold damp and are therefore no good for this plant, whatever the label says about them being sunny.
Note slug damage separately, with the date of planting out. If you find your losses cluster in the first fortnight after planting every year, the answer is to plant out later into warmer, drier ground and to protect the plants only over that short window rather than all season.