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!
African marigolds are beautiful, cheerful flowers that can brighten up any garden with their sunny colors and lovely fragrance. However these popular blooms are prone to infestations by nasty pests like scales which can quickly damage and disfigure the plants if left unchecked.
In this comprehensive guide, you’ll learn how to identify, treat, and prevent scale insects on your precious African marigolds, using both chemical and natural methods for safe and effective control.
What Are Scales?
Scales are small, sap-sucking insects that attach themselves to the stems, leaves, and flower buds of plants. They have oval-shaped, shells-like coverings that protect their bodies. Scales suck the juices out of plant tissues using their piercing mouthparts, eventually causing yellowing, wilting, stunting, and even death of the plant if infestations are severe.
On African marigolds, scales most commonly infest the stems and undersides of leaves occurring as bumpy white or brown spots that appear stuck to the plant. Their presence can be confirmed by the sticky honeydew secretions they leave behind.
Scales thrive in warm dry conditions and often go unnoticed until heavy infestations take hold, making early detection and treatment essential.
Natural Ways to Get Rid of Scales
For mild or limited scale infestations on African marigolds, less toxic, natural control methods are ideal. Here are some effective organic approaches:
Manual Removal
Gently scrape off visible scales using your fingernail or a soft brush, taking care not to damage the plant tissues. Check all leaf undersides and crevices where scales like to hide.
Horticultural Oils
Apply horticultural oil, which suffocates scales, according to label directions. Thorough coverage and repeat applications are needed for good control.
Insecticidal Soaps
Insecticidal soap sprays kill soft-bodied insects like scales on contact. For best results, spray in the morning and coat all plant surfaces, including the undersides of leaves.
Neem Oil
As a natural insecticide, neem oil is highly effective against scales when applied repeatedly. It smothers and kills juvenile stages.
Rubbing Alcohol
Using a cotton swab, rub scales off with 70% isopropyl alcohol to quickly destroy them. Be careful not to damage tender growth.
High-Pressure Water Sprays
Blast scales off the plants with a strong jet of water. Repeat often to disrupt growth. Focus on the undersides of leaves.
Chemical Treatments for Serious Infestations
For heavy scale attacks on African marigolds, you may need to use chemical pesticides when natural options fail to provide control. Always follow label directions carefully:
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Horticultural oils – Apply dormant oil sprays during winter and growing season oil sprays in summer. Coverage is critical.
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Insecticidal soaps – More potent than natural soaps, these provide quick knockdown of scales. Requires thorough application.
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Systemic insecticides – Applied as drenches or granules, these are taken up by the plant’s vascular system to kill scales feeding on it.
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Contact insecticides – Broad spectrum chemicals like malathion and carbaryl kill adult scales on contact and continue working for several days after spraying.
When using any chemical pesticide on African marigolds, be very careful to minimize harm to bees and other beneficial insects that may be present. Only apply them if absolutely necessary and according to manufacturer guidelines.
How to Prevent Scales on African Marigolds
Prevention is always the best solution for dealing with plant pests. Here are some tips to help avoid scale infestations on your African marigolds:
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Inspect plants frequently and look for early signs of scales before they multiply.
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Keep plants healthy with proper irrigation, fertilization, and pruning to make them more resistant to pests.
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Isolate and dispose of heavily infested plants to prevent spread.
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Remove weeds, plant debris, and dropped leaves/petals where scales may breed.
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Avoid excess nitrogen fertilization which promotes soft, sappy growth that attracts scales.
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Use row covers or garden fabric to exclude winged adult scales.
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Apply horticultural oils or insecticidal soaps early in the season to control juveniles before they mature and lay eggs.
By identifying and treating scale invaders promptly, and following good cultural practices to keep your African marigolds strong and healthy, you can enjoy a bountiful display of colorful blooms all season long free of unsightly and destructive scale damage. Don’t let these sneaky pests ruin the splendor of your cherished marigolds!
What is Scale on Plants?
Scale on plants sounds like a disease, and it even looks like it, but this actually refers to an infestation by one of more than 8,000 species of small insects that suck sap and belong to the superfamily Coccoidea.
These scale insects cling on to stems, branches, and even the leaves of plants they’re feeding sap from. But due to their appearance, they can often be mistaken for a plant disease instead.
They have a shell-like bump appearance and tend to firmly attach to their host plant. This immobile nature of theirs further perpetuates the notion that it may actually be a disease, but it’s not. They’re often covered in an armor and are found in clusters.
Understanding what they look like and taking action as soon as they’re first spotted is one of the most important factors when getting rid of scales on plants.
Step 2: Prune and Dispose of Infested Branches
If you believe your plant is infected, start by quarantining it to the side so that you can stop scales from spreading to other plants. It’s important to keep them away for at least three weeks to complete the lifecycle and to be sure that you’ve gotten rid of them for sure.
If it’s a small infestation, you don’t need to follow this step but it’s still recommended if you have any doubts. Like they say, better safe than sorry! Use your gardening shears to clip off any affected parts of the plant. Dispose of infested branches, twigs, and leaves.
Make sure not to put these clippings in your compost bin! They need to be disposed of to stop them from spreading.
The COMPLETE Guide to Getting Rid of Scale Insects
FAQ
How do you permanently get rid of scale on plants?
Does vinegar get rid of scale on plants?
What is the best spray for scale?
How do you get rid of scales in plant pots?
How do you care for African marigolds?
Overwatering or Poor Drainage: African Marigolds prefer well-draining soil, and overwatering can lead to root rot or other fungal diseases. Ensure the soil is well-drained and water the plants deeply when the top inch of soil feels dry. Avoid overhead watering to minimize moisture on the leaves.
Do African marigolds rot?
Your plant will look sickly, but don’t worry just yet – marigolds are pretty hardy. Generally root rot is a sign that you’ve overwatered your marigolds, or that they are planted in the wrong soil. Remove your African marigold from its environment, and remove any dead or dying plant parts with a sterile pair of shears or garden scissors.
Do African marigolds grow well if deadheaded?
If deadheaded regularly, African marigold plants will usually produce many large blooms. They grow best in full sun and actually seem to prefer poor soil. Growing African marigolds or French marigolds around vegetable gardens to repel harmful insects, rabbits, and deer is a gardening habit that goes back for centuries.
How often should you water African marigolds?
Water your African marigolds regularly—the standard one inch per week guideline works well for these plants. Do not overwater them because if the soil isn’t well drained, the plants are at risk of drowning or developing root rot. It’s fine for soil to dry out completely between watering.