Few situations are more disheartening to a gardener than finding a treasured landscape plant butchered by a hungry pest. The bright-green lady fern (Athyrium filix-femina) is usually pest-free, avoided by common garden foes such as rabbits and deer. No plant is immune to problems, however, and some pests may cause noticeable damage to a lady fern's fronds.
Slugs may feed on a lady fern, chewing irregular holes in the fronds and leaving a telltale trail of silvery slime. Preferring cool, moist conditions, slugs are most active in evening. You can reduce a slug population by eliminating its habitat. Remove weeds, boards, stones and debris from around the garden, and check under decks and meter boxes for hidden slugs. Either remove slugs by hand and drown them in soapy water, or set out shallow containers filled with beer, which lures slugs and in which they drown.
Mealybugs may form dense groups on a lady fern, and the groups may resemble patches of cotton. If you provide the proper cultural care for your lady fern, mealybug damage should be minimal. The mealybug population may drop in summer when temperatures are too high for the creatures. Spraying exposed mealybugs with a direct stream of water dislodges them. Naturally occurring predators of mealybugs often help solve a mealybug problem. Avoid using a broad-spectrum insecticide, which kills such beneficial predators and usually isn't effective against mealybugs because of their waxy, protective coating.
In the wild, lady fern is eaten by grizzly bears and elk, according to the Blue Planet Biomes website. Although lady fern is not preferred by deer, a starved or desperate deer will consider eating just about any plant. Lady fern often becomes tattered by midsummer, a Missouri Botanical Garden website article notes. That natural effect may be mistaken for damage from a small or large pest. Place your lady fern in a protected location to prevent wind from breaking its fronds.
Providing the proper cultural conditions helps to keep a lady fern vigorous and attractive. Lady fern is hardy in U.S. Department of Agriculture plant hardiness zones 4 through 8, where it performs best in partial to full shade and well-draining, moist soil. The plant may grow in a site that receives full sunlight, but only if its soil is never allowed to dry. Divide your lady fern every couple of years in spring to encourage it to have a tidier appearance and to keep its crown from rising out of the soil.
- Missouri Botanical Garden: Athyrium Filix-Femina
- Blomidon Nurseries: Ferns
- Blue Planet Biomes: Lady Fern -- Athyrium Filix-Femina
- White Flower Farm: Growing Guide Ferns
- University of California Integrated Pest Management Online: Mealybugs
- University of California Integrated Pest Management Online: Snails and Slugs Management Guidelines
- Deer-Departed.com: Deer-Resistant, Rarely Damaged Ferns