Plant Health Problems See Houseplants for a detailed discussion of the other problems that might occur on fern.

Diseases caused by Physiological/Environmental Factors:

Tip necrosis, physiological.
The margins and tips of the fronds shrivel and turn brown. Tip necrosis has been associated with many factors including uneven watering and low levels of relative humidity.

Although this condition mars the beauty of the plant, it is usually not serious. Affected tissues can be trimmed with a clean sharp knife or scissors. Problems can also be minimized by modifications in cultural care, with particular attention to uniform watering and adequate levels of relative humidity.

Insect Problems
Fern aphid, Idiopterus nephrelepidis.
This black aphid often infests the under surface of the fronds of the Boston fern, though seldom causing severe injury. The remedy is to spray with insecticidal soap or malathion, which are among the compounds registered for control of this pest in Connecticut, being sure to test spray any delicate ferns. Do not use malathion indoors or on Boston, maidenhair or pteris ferns. If the plants are in small pots, dip them in the mixture. Imidacloprid provides long lasting systemic control of aphids when applied as a root drench. Consult the labels for dosage rates and safety precautions.

Fern scale, Pinnaspis aspidistrae.
This armored scale infests Boston fern in greenhouses and homes. The female scale is about one-twelfth of an inch in length, pear-shaped and light brown in color. The male is smaller, pure white, narrow with parallel sides and has a distinct longitudinal ridge. Both occur on the underside of the fronds. Any sprays may need to be repeated if only the crawler stage is controlled. The remedy is to spray with insecticidal soap or malathion, which are among the compounds registered for control of this pest in Connecticut, being sure to test spray any delicate ferns. Do not use malathion indoors or on Boston, maidenhair or pteris ferns. If the plants are in small pots, dip them in the mixture. Consult the labels for dosage rates and safety precautions. Imidacloprid does not control armored scales.

Hemispherical scale, Saissetia coffeae.
This very convex brown hemispherical soft scale often infests the stems and fronds of Boston and other ferns. It is easily recognized by a raised "H" pattern on the surface of mature scales. Any control sprays may need to be repeated if only the crawler stage is controlled. The remedy is to spray with insecticidal soap or malathion, which are among the compounds registered for control of this pest in Connecticut, being sure to test spray any delicate ferns. Do not use malathion indoors or on Boston, maidenhair or pteris ferns. If the plants are in small pots, dip them in the mixture. Imidacloprid provides long lasting systemic control of aphids when applied as a root drench. Consult the labels for dosage rates and safety precautions.

Soft scale, Coccus hesperidum.
This soft scale is very thin, oval, and semi-transparent. It infests many different greenhouse plants including ferns. Any control sprays may need to be repeated if only the crawler stage is controlled. The remedy is to spray with insecticidal soap or malathion, which are among the compounds registered for control of this pest in Connecticut, being sure to test spray any delicate ferns. Do not use malathion indoors or on Boston, maidenhair or pteris ferns. If the plants are in small pots, dip them in the mixture. Imidacloprid, a restricted use insecticide applied as a soil drench by a licensed pesticide applicator, will provide season-long systemic control. Consult the labels for dosage rates and safety precautions. 

Twospotted spider mite, Tetranychus urticae.
This pest infests the undersides of the leaves, which become light yellow in color, and the plants have a generally unhealthy appearance. Sometimes the mites form webs, which more or less enclose the upper as well as the lower leaf surface. Among the compounds registered for control of this pest in Connecticut is insecticidal soap. Spraying with insecticidal soap will give sufficient control if applied at least twice at 7-10 day intervals, but note precautions under Fern aphid. The predatory mite, Neoseiulus fallacis, is most commonly found feeding where there are mite infestations. Special care should be taken with soap to obtain thorough spray coverage, because it only works on contact. Consult the label for dosage rates and safety precautions. Abamectin is an effective restricted use product. Avoid applying carbaryl or pyrethroids, which tend to be much more toxic to the predators than to the pest spider mites.

Yellow woollybear, Diacrisia virginica.
Ferns outdoors are often eaten by these yellow hairy caterpillars. Whitish, yellowish, or brownish hairy caterpillars feed upon the leaves of verbena and many other kinds of plants in the garden in late summer. This caterpillar is about 2" in length when fully grown and is covered with long hairs that vary in color from pale yellow to reddish brown. It makes its cocoon of its own hairy coat and silk, hiding in sheltered places, sometimes 20 to 30 being clustered together. The insect overwinters in this stage and the moths emerge in June and July. The moth has a wing spread of between 1 1/2 and 2", and is pure white with a few black dots, blackish antennae, and orange abdomen with a row of black spots on the back and along each side. Handpicking is the usual means of control.