Gadenin日本語Get the appSlugs and snails on young plants
Nothing else takes out a pansy planting as fast as slugs. The plants are soft, low to the ground, and put out in cool damp conditions that are ideal for slug activity, so a tray of young plants set out in the evening can be reduced to chewed stubs by morning. The damage is unmistakable once you know it: ragged irregular holes eaten from the leaf edges inward, whole seedlings grazed off at ground level, flower buds hollowed out, and silvery dried slime trails across the leaves and the soil around them.
The vulnerable window is the first three to four weeks after planting. An established pansy with a thick crown takes slug damage and carries on; a plant that has just gone in has no reserve and is simply eaten. Protect over that window and you rarely need to do anything afterwards.
Go out with a torch an hour or two after dark on the first mild damp evening after planting, and collect by hand. One session usually removes most of the population working that bed, because slugs concentrate on the newest soft growth available. Beyond that, clear away the flat damp hiding places within a few feet of the plants: upturned pots, boards, thick mulch pushed right up against the crowns, and piles of last season's leaves. Slug pellets based on ferric phosphate work and are safe around wildlife, but they only work if you use them at planting rather than after the damage is done.
- Water in the morning, not the evening Slugs feed on damp nights. A bed watered at dusk is far more attractive than the same bed watered at dawn and dry by nightfall.
- Hunt after dark for the first three nights A torch an hour after dark shows them out on the plants. Three consecutive nights of hand collecting after planting clears the bulk of the local population.
- Pull mulch back from the crowns Leave a clear two inch (5 cm) gap of bare soil around each plant. Mulch heaped against the crown is both a slug refuge and a cause of crown rot.
- Apply ferric phosphate pellets at planting Scatter thinly at the time you plant, not once the leaves are shredded. Reapply after heavy rain through the first month.
Aphids on the buds and shoot tips
Aphids gather on the flower stalks, the unopened buds and the newest leaves, and on pansies they are usually green or gray green. The first signs are indirect: buds that open lopsided or fail to open at all, a sticky honeydew film on the leaves below the infested growth, and later a black sooty mold growing on that film. Ants running steadily up and down the plants are a reliable indicator, because they farm the aphids and drive off the predators that would otherwise deal with them.
Aphids also matter more on pansies than on many plants because they transmit viruses. A plant with mottled, puckered, distorted leaves and streaked or broken flower color that does not improve after the aphids are cleared is very likely virused, and there is no treatment. Pull it out, bin it rather than composting it, and wash your hands before handling the healthy plants.
For a colony that is still small, a firm jet of water into the shoot tips three days running knocks it down without anything else. For a heavier one, insecticidal soap sprayed until it runs off both surfaces of the leaves works, but only on what it actually wets, so the undersides and the crown matter more than the tops. Aphid numbers rise fast in mild spells in the middle of an otherwise cold season, which is precisely when nobody is looking at the plants.
Leaf spots, downy mildew and powdery mildew
Three different leaf problems get called mildew and they behave differently. Powdery mildew shows as a dry white dust on the upper leaf surface and appears in warm dry weather on plants that are dry at the root. Downy mildew shows as pale yellow blotches on the top of a leaf with a gray purple fuzz on the underside directly beneath them, and it appears in cool wet weather with poor airflow, which is exactly pansy weather. Leaf spot shows as distinct round brown or purple spots with defined edges, often with a paler center, that grow and merge until the leaf dies.
All three are managed the same way, and it is mostly not a spray. Space the plants so air moves between them rather than packing a container to look full on the day it is planted. Water at the base and in the morning. Pick off and bin the affected leaves as soon as you see them, and clear all dead foliage out of the crown, because that is where every one of these problems overwinters and restarts. Do not compost the material.
If a whole planting is badly affected, the honest answer is usually to remove it and start again in fresh compost in a different spot, rather than to keep treating it. Pansies are cheap and quick, and the alternative is spending a season nursing plants that will never look right while they infect anything you plant beside them.
| Symptom | Likely cause | What to do |
|---|---|---|
| Ragged holes, slime trails | Slugs and snails | Hunt after dark; ferric phosphate at planting |
| Sticky leaves, distorted buds | Aphids | Water jet three days, then insecticidal soap |
| Mottled leaves, streaked flowers | Virus spread by aphids | Remove and bin the plant; no treatment |
| White dust on upper leaf surface | Powdery mildew | Improve airflow, water the root zone, remove leaves |
| Yellow blotches with gray fuzz beneath | Downy mildew | Space plants, water at the base in the morning |
| Round brown spots with defined edges | Leaf spot | Pick off affected leaves, clear crown debris |
| Sudden wilt, brown soft stem at soil level | Crown or root rot | Not recoverable; remove and do not replant there |
A plant that wilts and never recovers
A pansy that goes limp and stays limp after watering has a problem at the base, not at the top. Lift it and look at the stem right where it meets the soil. A brown, soft, sometimes water soaked patch at that point is crown rot, and it is caused by the crown sitting wet: planted too deep, mulch heaped against the stem, a container without free drainage, or simply a run of cold wet weeks in heavy soil. There is no cure. Remove the plant, take out the soil immediately around it, and do not put another pansy in the same spot this season.
Black root rot is the related problem below ground. The plant is stunted, the older leaves yellow, growth stalls, and when you lift it the roots are blackened and brittle rather than white and firm. It builds up in soil where pansies or violas have been grown repeatedly, which is why rotating the bed matters even for something as small as a pansy. If a bed has produced two poor plantings in a row, use it for something else and grow the pansies in fresh compost in containers.
The difference from simple drought is worth knowing, because it is the commonest misdiagnosis. A pansy short of water wilts in the warm part of the day and is standing upright again by the following morning, and one good soak fixes it. A pansy with rot is limp at dawn as well, and every further watering makes it worse.
Keep a note of which bed or container each planting went into and how it performed. Root rot problems build up in a specific place over years, and a two line record of where things did badly is what stops you replanting into the same soil next autumn.