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How to identify it
- Because the nematodes can't easily cross the larger veins, the damage is vein-bounded: on hostas, irises and lilies it forms stripes between the parallel veins, and on plants with a network of veins it forms angular, patch-like blotches.[1][3][4]
- Affected areas start yellowish or water-soaked, then turn brown and dry and may fall out, leaving a shot-holed or tattered leaf.[2][3][4]
- Begonias are an exception: there the damage is general yellowing, reddening or bronzing that isn't limited by the veins.[3][1]
Where it lives
Reported on ornamentals by extension services from Connecticut and Pennsylvania to Wisconsin and South Carolina.[1][3][2][4]
Biology and life cycle
Most foliar nematodes overwinter in leaf tissue, and they can survive a long time in dry plant debris.[4][2]
Splashing water from rain or overhead irrigation, and films of water on the leaves, let them move from infested tissue to new leaves and plants.[4][2]
They develop fastest at 70 to 75 °F; females lay eggs that each hatch into a single larva.[3]
Damage and signs
- The group attacks hundreds of plants, more than 700 species in all, including hosta, ferns, Japanese anemone, heuchera, iris, lilies, peony, phlox, chrysanthemum and begonia.[1][4][3]
- In gardens the damage is usually cosmetic rather than lethal, but it makes plants unattractive, and heavy infestations can stunt them.[2][3]
Health risk
They attack plants only; none of the sources reports any risk to people or pets.[2][1]
Control
Prevention
Avoidance matters most: inspect plants carefully before buying, choose only symptom-free plants, and never take cuttings or divisions from infested plants.[4][2]
Avoid overhead watering and keep the leaves as dry as possible.[4][2]
Sanitation
Remove infected leaves as soon as symptoms appear and clean up plant debris, where the nematodes can survive.[4][2]
Pesticides
Eliminating foliar nematodes is virtually impossible: Wisconsin notes that no chemical products are available for home gardens, and Penn State notes that insecticides can suppress them but not eliminate them, sometimes only at rates that injure the plant.[2][3]
Common questions
- Why do my hostas have brown stripes between the veins?
- Yellow-to-brown stripes that stop at the veins are typical of foliar nematodes, which can't easily cross the veins of the leaf.[2][4][1]
- Can I save a hosta with foliar nematodes?
- Getting rid of them completely is virtually impossible; removing infected leaves and keeping the foliage dry can reduce them, but don't use the plant for divisions or cuttings.[2][4]
Sources
- UConn Integrated Pest Management Program, “Foliar Nematodes on Ornamental Plants (J. Allen and L. Pundt).” ipm.cahnr.uconn.edu/foliar-nematodes-on-ornamental-plants/ (accessed 2026-10-17)
- University of Wisconsin-Madison Plant Disease Diagnostics Clinic, “Foliar Nematodes (UW Plant Disease Facts).” pddc.wisc.edu/wp-content/blogs.dir/39/files/Fact_Sheets/FC_PDF/Foliar_Nematodes.pdf (accessed 2026-10-17)
- Penn State Extension, “Foliar Nematodes (updated July 7, 2025).” extension.psu.edu/foliar-nematodes (accessed 2026-10-17)
- Clemson University Regulatory and Public Service Programs (Plant Problem Clinic), “Foliar Nematode of Hosta (Plant Problem Clinic fact sheet).” clemson.edu/public/regulatory/plant-problem/fact-sheets/foliar-nematode-hosta.html (accessed 2026-10-17)
- iNaturalist, “Aphelenchoides taxon page (order and family).” www.inaturalist.org/taxa/372239 (accessed 2026-10-06)