Just as your indoor citrus tree is looking good and developing fruits, you notice little pests have appeared! While indoor citrus trees experience less pest pressure than their outdoor cousins, they are still susceptible to problems like aphids and spider mites. We’re going to cover common citrus tree pests and diseases as well as how to treat them.
Dealing With Common Indoor Citrus Tree Pests – The Essentials
Some of the most common pests of indoor citrus trees include sap-sucking pests like aphids, mealybugs, and spider mites. Regularly monitor pests and treat them when necessary to keep your plant healthy. Insecticidal soap and neem oil are some of the best treatment methods.
The Most Common Indoor Citrus Tree Pests and Diseases
Aphids
If you’ve never dealt with aphids, consider yourself lucky. These tiny, sap-sucking pests pierce citrus leaves and drink up the sap. Since mature leaves have a thicker outer layer, aphids typically only affect young leaves.
Aphids themselves are tiny, ranging from 1/16 to 1/8 inch long. They are often green, but they can also be red, brown, yellow, and gray.
Generally, aphids won’t cause serious damage to your citrus trees. However, they can cause small, discolored speckles.
With that said, the main issue with aphids is the correlation with diseases. These pests release a sticky substance known as honeydew which can lead to the formation of gray sooty mold.
Mealybugs
Mealybugs are another type of sap-sucking pest. They have flattened ovular bodies covered in a waxy, white substance. While they look a bit like cotton fluff, don’t think these pests are harmless.
These pests also suck plant sap and release honeydew. If enough mealybugs feed on a plant’s stem, they can cause premature fruit drop.
Mealybugs typically occur on indoor citrus when other plants introduce them. Therefore, it’s essential to check all plants for pests before you bring them into your home.
Whiteflies
Despite their name, whiteflies aren’t flies. Instead, they’re sap-sucking insects that are closely related to the aphids mentioned above and mealybugs.
Adult whiteflies are small insects with two powdery white wings. The nymphs look even smaller and white or clear.
Whiteflies typically occur once they’ve been introduced into your home on other plants. That said, citrus trees are more susceptible to these pests if they are under-watered or over-fertilized.
Scale Insects
Scale insects are another group of sap-sucking pests. They are small, flattened ovular pests that can be brown, gray, or white. Since these pests are flat and relatively immobile, people often mistake them for bacteria or viruses.
As the insects suck on citrus leaves and stems, they can cause discoloration and produce honeydew.
Scale insects like warm temperatures, which means they thrive in the same conditions as citrus trees.
Spider Mites
Spider mites are small arachnids that suck the contents of plant tissues. They are less than 1/20 of an inch long, so they’re often quite hard to spot until they appear in large numbers. Along with the mites themselves, you can look for the spider-like web they form on the undersides of leaves.
A small number of spider mites isn’t cause for concern, but larger infestations can lead to noticeable damage on leaves. Damage appears as stippling on leaves and then changes to total discoloration and leaf drop.
Drought-stressed citrus trees are more susceptible to spider mites, so it’s essential to keep your tree well watered.
Leafminers
Leafminers are a group of insect larvae that feed on the inside of leaves, creating patterns. The citrus leafminer, the larvae of a small moth, is the leafminer that frequently damages citrus trees.
The citrus leafminer is a small, orange larva, but you may see damage from the pest before you see the larva itself. Check leaves for squiggly channels filled with dark-colored frass.
Leafminers are more likely to occur in cooler conditions. They also only attack newer leaves, so they’re a more significant threat to young trees without many mature leaves.
Sooty Mold
Sooty mold is a type of gray fungus that forms when sap-sucking insects secret honeydew. As your tree’s leaves become covered with mold, they are less able to complete photosynthesis.
The best way to prevent sooty mold is to treat these sap-sucking pests ASAP. Without honeydew, sooty mold won’t form.
If your plants develop this fungal disease, the first step is to treat the honeydew-producing pests. Once these pests are gone, the sooty mold will naturally decline. You can also spray your plants with a mixture of dish soap and water to wash off the sooty mold.
Pesticide and Insecticide Options
Horticultural Oil
Horticultural oils are a group of oils used to control plant pests. They may be plant-based or petroleum-based. Monterey Horticultural Oil is one good option.
These oils work by suffocating soft-bodied pests, including aphids, mealybugs, whiteflies, and spider mites. Therefore, it’s essential to make direct contact with these pests.
You can use horticultural oil on all stages of pests, including eggs, nymphs, and adults. Spraying during a cloudy day or evening is better than spraying mid-day.
Horticultural oil may come as a concentrate or as a ready-to-spray product. Therefore, it’s important to follow product instructions and dilute horticultural oil with water if necessary. Use a sprayer to coat the pests thoroughly.
Neem Oil
Neem oil is made from the seeds of the neem tree. Not only does neem oil work by suffocating pests, but it also contains compounds such as azadirachtin that stop insects from feeding and disrupt insect growth. You can find many neem oil products, including this Bonide Neem Oil.
Neem oil can be used to treat a wide variety of pests, including aphids, whiteflies, and leafminers. You can spray neem oil as soon as you detect a pest.
To apply neem oil, follow product instructions for dilution. Once adequately diluted, spray your citrus tree. Since this product mainly works on contact, it’s important to coat all sides of your plant.
Insecticidal Soap
These products are soaps that are specifically designed to kill pests. They work by suffocating pests like aphids, spider mites, scale, and mealybugs.
Insecticidal soaps must thoroughly coat pests to be effective. Therefore, make sure to cover all sides of your citrus tree.
Most soaps need to be diluted, so make sure to read product instructions. Others, such as this Bonide Insectidicial Soap, are pre-diluted and ready to apply.
While specific insecticidal soaps are your best bet, you can also use regular dish soap. Simply mix a few tablespoons of soap per gallon of water, then spray the mixture on your tree.
Synthetic Pesticides
While most indoor citrus pests can be controlled using the methods above, you can opt to use synthetic pesticides. These include organophosphates, neonicotinoids, and pyrethroids.
Before you use these products, you should be aware that they may also be toxic to pets and humans. Therefore, it’s essential to read warning labels and apply as directed.
Some of these products are broad-spectrum and kill a wide variety of pests. Others target specific types of insects, such as caterpillars.
If you apply pesticides repetitively, pests may develop immunity. Therefore, only apply as necessary.
How to Use Pesticides & Insecticides on Citrus Trees
Before selecting a pesticide to use, make sure it will effectively treat the target pest. You should also take note of any other insects it will affect.
When choosing pesticides for outdoor use, you should choose the most selective product to avoid harming beneficial insects. However, this isn’t a big concern when treating indoor plants.
Once you select an insecticide, read all of the product instructions. Make sure to take note of application rates, the best time of day to apply, and any safety precautions. It should go without saying, but follow these product instructions!
While pesticides would be great if they worked instantly, many take a few hours or days to kill pests. Therefore, wait a few days before reapplying a product.
Since pests can develop tolerances to insecticides, you should only use them when necessary. If you notice only a handful of aphids or spider mites, simply use a soapy rag to remove them.
Managing Indoor Citrus Tree Pests & Diseases
The first step of managing pests and diseases on citrus is proper prevention. It’s essential to take note of your environment and provide appropriate citrus tree care.
Inspect New Plants
While pests can easily find their way to outdoor citrus trees, they find indoor plants more challenging. Many indoor pests make their way into your home when you introduce a new plant.
Before bringing a new houseplant indoors, give it a thorough inspection to look for pests like aphids, spider mites, and mealybugs. Even if you don’t see any signs of pests, it’s always a good idea to quarantine new plants in a separate room for a few weeks.
Keep Plants Healthy
Healthy trees can better fight off pests and diseases, so you must provide your trees with the care they need. Here’s a quick refresher on the basics of citrus tree care.
- Light: Provide trees with between six and ten hours of bright, direct light each day.
- Soil: Use well-draining, slightly acidic potting soil.
- Fertilizer: Use a balanced fertilizer sporadically throughout the year.
- Water: Water citrus trees thoroughly when the top three to four inches of soil is dry. Make sure to thoroughly saturate the soil each time you water.
- Pruning: Pruning indoor citrus trees during the late winter or early spring creates a proper tree shape and improves plant health.
- Temperature and humidity: Keep your citrus trees in a room that is between 60-85ºF. Maintain moderate to high humidity.
- Repotting: Consider repotting your indoor citrus trees every 2 to 4 years.
- Location: Indoor citrus trees thrive in sunny aspects such as near a south, east, or west-facing window.
Wrapping Up
Becoming familiar with common indoor citrus pests and diseases will help you spot them as soon as they occur. Once you spot a pest, follow the treatment methods described above. With the proper treatment and continued care, your tree will regain its health, and you’ll get to enjoy all its associated benefits.
For more, see our in-depth guide to the meaning and symbolism of citrus trees.
Briana holds a B.S. in Plant Sciences from Penn State University. She manages a small market garden where she grows vegetables and herbs. She also enjoys growing flowers and houseplants at home.
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