Hosta Diseases and Pests: Pictures, Symptoms, Crown Rot
Hostas have few serious problems, but the ones they have are easy to confuse: slug holes, deer damage, leaf nematodes, viruses, several rots and plain weather damage. This page helps you tell them apart from what you can see, and says what to do about each. The diseases covered are the ones Penn State Extension lists for hosta: anthracnose, petiole rot, Fusarium root and crown rot, bacterial soft rot, Hosta Virus X and other viruses, plus foliar and root-knot nematodes (Penn State Extension).
Quick answer: what is wrong with my hosta?
- Smooth but irregular holes along the edges or between the veins — slugs or snails (Missouri Botanical Garden).
- Leaves gone overnight, stalks left with ragged, torn ends — deer (Missouri Botanical Garden). Stalks cut cleanly, as if by scissors, point to rabbits (Iowa State University Extension).
- Brown streaks or wedges bounded by the veins — foliar nematodes (Missouri Botanical Garden).
- Mottling, “ink bleed” along the veins, puckered or twisted leaves — Hosta Virus X or another virus (American Hosta Society).
- Lower leaves yellow and collapse, stems rot at the soil line — petiole (crown) rot or another rot (Iowa State University Extension).
Weather causes damage that looks like disease too: frost, hail, sun scorch and drought. Use the table below to narrow it down, and confirm serious problems with your local extension plant diagnostic clinic before destroying plants.
Hosta problem identifier: symptoms, causes and next steps
| What you see | Likely cause | How to confirm | What to do |
|---|---|---|---|
| Irregular holes in leaves, often with slime trails | Slugs or snails (Missouri Botanical Garden) | Check leaves with a flashlight after dark | Hand-pick at night, board or beer traps, iron-phosphate baits; remove debris they hide under (UC IPM) |
| Leaves torn off, stalks with ragged ends; damage appears overnight | Deer (Iowa State University Extension) | Hoof prints, droppings, height of damage | Fencing or repellents (Iowa State University Extension) |
| Leaves snipped off cleanly near the ground | Rabbits (Iowa State University Extension) | Low damage, droppings | Chicken-wire enclosure or fencing (Iowa State University Extension) |
| Light green to yellow, then brown stripes between the veins, on older leaves first | Foliar nematodes (Aphelenchoides spp.) (Penn State Extension) | Lab test of affected leaves | Remove and destroy affected leaves; water without wetting the leaves, because splashing spreads them (Penn State Extension) |
| Mottling, ringspots, color “bleeding” along veins, puckered or twisted leaves | Hosta Virus X (HVX) or another virus (UConn IPM) | HVX test strips or a diagnostic lab (UConn IPM) | No cure: destroy the plant, don’t compost it; disinfect tools (American Hosta Society) |
| Large tan spots with dark borders; centers may fall out; tiny black dots in the spots | Anthracnose (Colletotrichum) (Penn State Extension) | Worse in wet weather and wet sites (Illinois Extension) | Remove spotted leaves, avoid overhead watering, improve air flow (Penn State Extension) |
| Lower leaves yellow and collapse; soft brown rot at the base of the leaf stems; white threads and tiny round bodies in hot, humid weather | Petiole rot / southern blight (Sclerotium rolfsii) (Iowa State University Extension) | White fungal growth and sclerotia at the base; lab confirmation | Remove the plant and surrounding soil — see the crown rot section |
| Wet, foul-smelling decay of leaf stems and lower leaves | Bacterial soft rot (Pectobacterium) (Penn State Extension) | Smell and wet texture; lab confirmation | Remove infected plants; disinfect tools and wash hands between plants (Penn State Extension) |
| Plant emerges late and stunted, leaves yellow then brown, dry decay of stems at the soil line | Fusarium root and crown rot (Fusarium hostae) (Penn State Extension) | Dig and inspect roots; lab test | Remove infected plants; avoid wounding roots when transplanting (Penn State Extension) |
| Small galls or swellings on the roots | Root-knot nematodes (Meloidogyne spp.) (Penn State Extension) | Dig and wash a root | Destroy infected plants; don’t replant hostas in that spot (Penn State Extension) |
| Brown leaf edges (scorch) or bleached patches that turn brown (sunburn) | Heat, drought and too much sun (Purdue Plant & Pest Diagnostic Lab) | Damage on the sunny side; hot, dry spell | Water deeply, mulch, move the plant to more shade |
| Puckered or cupped leaves with soft, dark, water-soaked edges in early spring | Frost or cold damage (University of Minnesota Extension) | Recent cold spell; many plants affected at once | Nothing; new growth after the cold is normal (University of Minnesota Extension) |
| Shredded holes on exposed leaves after a storm | Hail | Recent hail | Cosmetic; trim the worst leaves |
| Cupped leaves whose edges split and tear as the season goes on | ”Drawstring effect”, a growth disorder of some variegated cultivars (American Hosta Society Hosta Helper) | Same cultivar affected every year | Cosmetic; choose another cultivar if it bothers you |
Slugs and snails
Slugs and snails cause most of the holes in hosta leaves. They feed at night and hide by day under debris, dense ground covers and mulch. Control works best when several methods are combined (UC IPM):
- Remove hiding places — leaf litter, boards, low dense plantings near the hostas.
- Hand-pick after dark with a flashlight, regularly.
- Trap them under boards raised slightly off the ground, or in beer traps sunk level with the soil; empty traps daily.
- Water in the early morning, ideally with drip lines, so the bed is dry by evening.
- If you use bait, choose iron phosphate. UC IPM describes iron-phosphate baits as safer around children, pets and wildlife, and metaldehyde baits as particularly poisonous to dogs and cats (UC IPM).
Anthracnose
Anthracnose shows up as large, irregular to round tan spots with dark borders; the centers may drop out and tiny black fungal structures can be seen in the spots (Penn State Extension). It is more common in wet or over-watered locations (Illinois Extension). It spoils the look of the plant rather than killing it. Remove infected leaves, water so that the foliage stays dry, and give plants room for air to move; a protective fungicide can be used on healthy leaves (Penn State Extension).
Hosta Virus X (HVX)
HVX infects only hostas. It is not spread by insects or nematodes; it moves in infected sap — on tools, hands and clothing — and mainly through the propagation of infected plants (UConn IPM). Because large nurseries propagate by tissue culture, one infected stock plant can spread the virus widely (Illinois Extension). Symptoms vary by cultivar: mottling, color changes along the veins (“ink bleed”), puckering, twisting, ringspots, stunting and browning. They can take months or years to appear, and some infected plants never show them (UConn IPM; Illinois Extension).
- Disinfect tools between plants when dividing or deadheading, for example in a 10% bleach solution (American Hosta Society). Our dividing guide includes this step.
- Quarantine new hostas in a separate spot or pot until you are confident they are virus-free (UConn IPM).
- Destroy, don’t compost infected plants; there is no cure (American Hosta Society). Never divide and pass on a plant you suspect.
- Test suspicious plants with HVX test strips or at a plant diagnostic lab rather than relying on looks alone (UConn IPM).
Hosta crown rot: what it looks like and what to do
“Crown rot” is used loosely for more than one disease. Iowa State uses it for petiole rot caused by Sclerotium rolfsii (Iowa State University Extension), while Penn State also describes Fusarium root and crown rot and bacterial soft rot, which rot the base of the plant (Penn State Extension). They look similar early on, so the response is similar too.
Typical signs
- Yellowing and browning of the leaf margins, starting with the lower leaves; a soft, brown, mushy decay at the base of the leaf stems; eventually the leaves collapse and lie flat on the ground (Iowa State University Extension).
- In warm, humid weather, white cottony threads fanning out over the stem bases and soil, and tiny round sclerotia — about 2–3 mm, white at first and brick-red later (University of Arkansas Extension; Iowa State University Extension). This points to Sclerotium rolfsii.
- A wet, bad-smelling decay of the leaf stems points to bacterial soft rot (Penn State Extension).
- A plant that comes up late and small, with a dry decay at the soil line, points to Fusarium root and crown rot (Penn State Extension).
Crown rot action plan (checklist)
- Photograph the plant (see below) and, if it is valuable, send a sample to your state extension plant diagnostic clinic.
- Bag all infected plant parts straight away and put them in the trash, not the compost; remove the top several inches of soil around the plant without spilling it (Illinois Extension). Iowa State suggests replacing the soil to a depth of 6–8 inches (Iowa State University Extension).
- Scrape and wash soil off every tool used in the infested spot before touching other plants (Iowa State University Extension).
- Don’t replant hostas there right away: the sclerotia can persist in soil for several years (University of Arkansas Extension).
- Fix the conditions: keep a mulch-free zone around the crowns (Iowa State University Extension), don’t pile soil against the stems (Penn State Extension), and water at soil level in the morning.
Can a hosta recover from crown rot? Don’t count on it. Iowa State recommends digging up and removing hostas with crown rot symptoms and notes that no registered fungicides are effective against petiole rot (Iowa State University Extension).
How to photograph a sick hosta (for a diagnostic clinic or a forum)
Good photos make it much easier for an extension clinic or a hosta society member to help:
- Whole plant from about 1 m (3 ft), so the pattern (one side, all leaves, only old leaves) is visible.
- One affected leaf, top and underside, flat, in shade, with a coin or ruler for scale.
- Close-up of the edge between healthy and damaged tissue — this is where lesions, streaks or mottling are clearest.
- Base of the plant with mulch pulled back: stems at soil level, any white threads or small round bodies.
- A dug-up root if the plant is stunted.
- Note the cultivar name, the date, recent weather and how you water.
Prevention checklist
- Buy plants from trusted sources (Illinois Extension), inspect them before planting and quarantine new hostas (UConn IPM).
- Space plants at their mature width so air can move between them (see the size on each cultivar page).
- Water at the base of the plant in the morning so wet foliage dries quickly (University of Kentucky Extension).
- Keep mulch and soil off the crown.
- Disinfect tools between plants when dividing.
- Clear dead leaves and debris in fall to take away slug hiding places (UC IPM). See what to do with hostas in the fall.
Frequently asked questions
What does crown rot look like on a hosta?
Lower leaves yellow and collapse because their stems rot at soil level; in warm, humid weather there are often white threads and small round seed-like bodies at the base. See the crown rot section above.
What fungus grows on hostas?
The main fungal problems are anthracnose (Colletotrichum), petiole rot (Sclerotium rolfsii) and Fusarium root and crown rot (Penn State Extension). White fan-shaped growth at the base in summer is a warning sign of petiole rot.
Is Hosta Virus X contagious to other plants?
HVX infects only hostas and spreads in sap, mainly on tools and hands and through propagation of infected plants (UConn IPM). Treat every infected hosta as a risk to your other hostas.
Why are my hosta leaves turning yellow?
Too much sun and drought can cause it, but if the yellow lower leaves collapse at the soil line, check for petiole rot (Iowa State University Extension).
Should I cut off diseased hosta leaves?
Yes for anthracnose and foliar nematodes: remove and destroy affected leaves (Penn State Extension) and disinfect your pruners. Virus symptoms are different — there is no cure, so the plant should be destroyed rather than trimmed (American Hosta Society).
Related guides
- How to divide and transplant hostas — including tool hygiene against HVX
- Hosta care guide
- Are hostas poisonous? — pet-safe slug control
- Slug and deer deterrents · Deer repellents
Sources
- Penn State Extension — Hosta Diseases
- Iowa State University Extension — Pests and Diseases of Hosta
- Iowa State University Extension — Hosta Petiole and Crown Rot
- Iowa State University Extension — Why are my hostas browning/yellowing, then collapsing?
- Missouri Botanical Garden — Hosta Problems (visual guide)
- University of California IPM — Snails and Slugs (Quick Tips)
- University of Minnesota Extension — Hosta: leaves malformed
- UConn Integrated Pest Management — Hosta Virus X fact sheet
- American Hosta Society — How to Identify HVX – Hosta Virus X
- Illinois Extension, Home, Yard & Garden Pest Newsletter — Hosta Virus X
- Illinois Extension, Home, Yard & Garden Pest Newsletter — Hosta petiole rot
- Illinois Extension Hort Answers — Anthracnose (annuals and perennials)
- University of Arkansas Cooperative Extension — Southern blight (FSA-7574)
- Purdue Plant & Pest Diagnostic Lab — Leaf scorch / sunburn on hosta
- American Hosta Society Hosta Helper — Hosta ‘Lunar Eclipse’ (drawstring effect)
- University of Kentucky Cooperative Extension, Daviess County — Watering