Scale on plants are sap-sucking pests that attach themselves to twigs, leaves, branches, and fruits of host plants. This guide shares the best ways for scale control on houseplants.
There are more than 8,000 species of scale insects in the world and over 1,000 in North America alone.
They are such oddly shaped and immobile pests that they often resemble shell-like bumps rather than insects. In many cases, heavy infestations build up unnoticed before plants begin to show damage.
Large populations may result in poor growth, reduced vigor and chlorotic (yellowed) leaves. If left unchecked, an infested host may become so weak that it dies.
If you suspect your plant has a scale infestation, then read this complete guide to learn what they are, how to identify them, and then get rid of them in 5 simple steps!
Australian tree ferns are striking garden specimens, but their delicate fronds are also a magnet for scale insects. These tiny sap-sucking pests can quickly proliferate covering leaves and stems. Left uncontrolled heavy infestations of scale can seriously weaken and potentially kill tree ferns. Getting rid of scale protects the health of these architectural beauties.
Identifying Scale
Scale insects often go unnoticed until plants show signs of damage. Look for the following clues that scale may be present:
- Yellowing or browning fronds
- Premature leaf drop
- Stunted growth
- Sticky honeydew residue on leaves
- Sooty mold fungal growth
Inspect the undersides of fronds and stems closely to spot the scale insects themselves. These bugs appear as tiny immobile bumps clustered on the plant surface. Scales may be brown, black, white or pink depending on species. They have a flat oval shape with a protective waxy coating.
Scale primarily feed on sap they draw directly from plant tissue Large infestations can drain enough fluids to desiccate leaves and stunt growth. Scale excrete a sticky sugary substance called honeydew as they feed. This residues coats leaves, causing black sooty mold to develop
Removing Light Infestations
If scale is limited to just a few fronds, simply prune them off. Remove the entire frond at its base on the plant’s trunk. Make sure not to leave any portion of the stem, which could allow scale to spread back into the plant.
Seal pruned fronds immediately in a plastic bag and discard in the trash to prevent scales from escaping back into the garden Sterilize pruning tools before making any other cuts to avoid spreading scale.
For light scale present on just part of a frond, use a soft brush or cotton swab dipped in alcohol to scrub them off. Concentrate on the underside area where the bugs hide. Be thorough but gentle to avoid damaging tender frond tissue.
Managing Heavy Infestations
When scale is widespread across numerous fronds and stems, pruning alone is not practical. Insecticidal treatments are required to knock back heavy scale populations:
- Horticultural oils – These oils smother insects and eggs. Coat all leaf surfaces for full effect.
- Insecticidal soaps – Soaps dissolve scale’s waxy coating, causing dehydration. Repeat applications are needed.
- Neem oil – Disrupts scale’s reproduction and feeding. Must contact bugs directly to work.
- Systemic insecticides – Taken up by the plant and make its tissues toxic to scale. Use as a last resort due to toxicity concerns.
Completely drench all fronds, stems, and trunk tissue with whichever treatment you select. Scale often form dense clusters in protected areas like frond bases and trunk crevices. Be sure to penetrate these infestation hot spots.
Make two applications spaced 7-10 days apart to catch newly hatched nymphs from eggs not destroyed during the first treatment. Monitor closely and spot treat any areas showing renewed scale activity.
Preventing Scale Recurrence
While insecticide applications provide immediate knockdown of existing scale populations, addressing underlying factors that promote infestations is key to preventing recurrence:
-
Improve air circulation – Avoid overcrowding of plants. Prune lower fronds to enhance airflow within foliage.
-
Increase sunlight – Scale thrive on plants in excess shade. Move tree ferns or thin canopy to boost sunlight exposure.
-
Prune selectively – Remove old fronds as they age to encourage new growth that is less susceptible to scale. Avoid shearing tree ferns into tight globes, which creates ideal dense habitat for scale colonies.
-
Reduce stress – Keep plants healthy through proper watering, fertilization and soil conditions to make them more resistant to scale.
-
Monitor routinely – Inspect plants often to detect scale early before infestations intensify. Spot treat small colonies using less disruptive methods like pruning or alcohol removal.
-
Encourage natural enemies – Lady beetles, lacewings and parasitic mini-wasps help control scale. Avoid broad-spectrum insecticides that harm populations of these beneficial insects.
Tree ferns are unique plants that deserve special care and effort to keep them looking their best. Staying vigilant for scale and taking prompt, thorough action at first signs of infestation is the key to success. With persistence and patience, you can eliminate scale insects and maintain a glorious scale-free Australian tree fern.
Types of Scale Insects on Plants
Scale insects can be divided into two groups:
Armored (Hard): Secrete a hard protective covering (1/8 inch long) over themselves, which is not attached to the body. The hard scale lives and feeds under this spherical armor and does not move about the plant. They do not secrete honeydew.
Soft scale: Secrete a waxy film (up to 1/2 inch long) that is part of the body. In most cases, they are able to move short distances (but rarely do) and produce copious amounts of honeydew. Soft scale vary in shape from flat to almost spherical.
How to Control and Get Rid of Scale on Plants Effectively
Getting rid of scales is a combination of a few very simple steps that will give you perfectly healthy plants that are free of these insects. Let’s look at what these are:
The COMPLETE Guide to Getting Rid of Scale Insects
FAQ
How do you treat fern scales?
How do you permanently get rid of scale on plants?
What does fern scale look like?
Does vinegar get rid of scale on plants?