How to Treat Problems With Staghorn Ferns

Staghorn ferns (Platycerium species) are exotic, elegant and relatively disease-free. Common problems are overwatering, watering with softened water, and placing them in direct sunlight. They are susceptible to spider mites, wet rot and some other common plant diseases. Staghorn ferns produce brown patches of spores that are sometimes mistaken for disease.

Distilled water

Insecticide

Sprayer

White sheet of paper

Check the sunlight. Staghorn ferns should not get direct sunlight. The best light is bright but indirect. Morning sun can be tolerated for a few hours. Move the staghorn to an area with better lighting if it is browning or yellowing out.

Let the plant dry between waterings. Staghorn ferns should become completely dry -- all the way through -- between waterings. A common cause of rot and losing leaves is overwatering. Signs include black spots on the guard leaves that can spread rapidly and kill the plant. This is a fungus called rhizoctonia (see Reference 1). Apply a fungicide or let the plant dry out completely and water moderately until the spots disappear.

Water with distilled water. Use tap water if it has a low salt content. Softened water will cause old leaves to brown out quickly and can even kill the plant. To get rid of salt water, completely soak and drain with distilled water.

Check for insects. In some areas, spider mites can cause leaves to brown out and die early. Spider mites are tiny -- about the size of the period at the end of this sentence. To check for spider mites, shake the plant or leaves over a white sheet of paper. The tiny little mites will fall onto the paper. Use a magnifying glass to spot them, or look for tiny dots that are moving across the paper. Spider mites can be treated with oil insecticides -- some horticulturists say not to use oils on staghorns, so check with your local distributor for information on the best insecticide to use.

Don't mistake spores for scaling or other leaf diseases. Mature healthy staghorns produce brown patches or spots of spores that are a normal process for the plant. If in doubt, describe these spots to your local distributor to determine if they are spores or disease.

Other insect pests include mealy worms and scaling insects. Use a non-oil-based systemic insecticide and apply it throughout the moss backing. If an oil-based insecticide is needed, check with your local distributor to make sure it is safe to use on staghorns. One problem with oil insecticides is that you are instructed to "polish" the leaves with the oil. Staghorns have a frosting of white hairs on the undersides of their leaves--this is a natural and healthy part of the leaf. Applying oil insecticides can damage these hairs (see Reference 2).