I have a mammoth fern in my sunroom. Recently it has started weeping a sticky substance that falls on the floor and windows. What is it and why has it started doing this? I have had this fern for six years.
The Gardener’s Answer
Hello, Dee in Ohio: From what you have described, it sounds like your fern has some insect issues. The fern itself is not producing this sticky substance, but instead the insect that is feeding on your plant is secreting honeydew. Many insects secrete honeydew as they feed on our plants, but aphids are the probably the most common. Soft scale, mealybugs, and whiteflies are also culprits. They are all plant-sucking insects that feed on the sap of the plants, and as a result excrete this sticky substance known as honeydew. It lands wherever it lands and sooty mold, a type of fungus, is a secondary problem that grows on the honeydew. For now it is important to have the insect positively identified. Look on the underneath part of the foliage, which is where you will find these insects. If the plant is not heavily infested, pruning or a steady stream of water might take care of the issue, but if the plant seems to have a lot of insects you may need to use a soap, oil, or systemic. You can take a sample to your local garden center to have the insect identified and then see what products they carry to manage the problem.