Fern Common Disease Problems
Leaf Spots: These may be caused by a fungus or bacterial disease. They usually cause small to large spots to form on the fronds possibly surrounded by a halo of lighter colored tissue. Burpee Recommends: Remove infected plant parts. Avoid overhead watering. Contact your Cooperative Extension Service for recommendations.
Leaf Tip Burn: This is a condition when the tips of the frond and leaflets brown and die. Burpee Recommends: This is usually caused by overfertilization or overly dry conditions.
Rhizoctonia Blight: This causes brow, irregularly shaped spots on the foliage close to the crown or on the top. Spots spread and webbing forms from frond to frond. Burpee Recommends: Contact your Cooperative Extension Service for recommendations.
Root Knot Nematodes: Microscopic worm-like pests that cause swellings (galls) to form on roots. Plants may wilt or appear stunted. Burpee Recommends: Do not plant into infested soil.
Root Rots: A number of pathogens cause root rots of seedlings as well as mature roots. Burpee Recommends: Practice crop rotation and do not plant related crops in the same area for several years. Pull up and discard infected plants. Make sure your soil has excellent drainage. Contact your Cooperative Extension Service for recommendations.
Fern Common Pests and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Mealybugs: Mealybugs are 1/8 to ¼ inch long flat wingless insects that secrete a white powder that forms a waxy shell that protects them. They form cottony looking masses on stems, branches and leaves. They suck the juices from leaves and stems and cause weak growth. They also attract ants with the honeydew they excrete, and the honeydew can grow a black sooty mold on it as well. Burpee Recommends: Wash affected plant parts and try to rub the bugs off. They may also be controlled by predator insects such as lacewings, ladybugs and parasitic wasps. Check with your Cooperative Extension Service for pesticide recommendations.
Scale: Small bugs look like brown, black, gray to white bumps on the stems of plants. Scale may not have any apparent legs and may not move. Scales have a sucking mouth part. Scale may produce honeydew so leaves and stems may be sticky. Scale can weaken the plant causing it to grow very slowly and may wilt at the middle of the day. Burpee Recommends: Completely spray the stems with Insecticidal soap. For a severe infestation contact your local County Extension Service for recommendation for your area.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Spider Mites: These tiny spider-like pests are about the size of a grain of pepper. They may be red, black, brown or yellow. They suck on the plant juices removing chlorophyll and injecting toxins which cause white dots on the foliage. There is often webbing visible on the plant. They cause the foliage to turn yellow and become dry and stippled. They multiply quickly and thrive in dry conditions. Burpee Recommends: Spider mites may be controlled with a forceful spray every other day. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for miticide recommendations.
I have regular spots on the underside of my fern fronds. What is the problem? There is no problem! There are actually the spores or fruiting bodies of the fern.
Can I grow ferns in a container? Yes, ferns are fine for containers. Be sure they do not dry out.
Are ferns deer resistant? Yes, ferns do tend to be deer resistant.
Do ferns ever bloom? No, ferns are not blooming plants. They are an ancient group of plants that reproduce by spores.
Can you eat ferns? Yes! When ferns emerge in spring the new growth appears curled up, like the top of a violin. These are called “fiddleheads” and the fiddleheads of ostrich ferns are edible. You have to be sure to harvest them when you see them or they will unfurl as they grow. Do not eat the fiddleheads of any other kind of fern, and do not eat the ostrich fern fiddleheads without thoroughly cooking them first.