Philodendron plants are generally resilient plants, and although they aren’t prone to diseases or pests, there are a few ailments to watch out for, especially when the plant is not kept under proper conditions.
The common pets that will attack philodendrons include aphids, mealybugs, scales and spider mites. These are routinely found on other houseplants as well.
Beyond the usual culprits, philodendrons can be susceptible to diseases like leaf spot, blight, and other diseases caused by improper keeping conditions.
To help you get an overview of the various pests, diseases, as well as their causes, symptoms, and treatments, I’ve put together this comprehensive guide to the most common pests or diseases to affect philodendron plants.
Common Philodendron Pests
Even if philodendrons are kept indoors, houseplants aren’t fully protected from pests. Pests can get indoors through a number of ways including contaminated tools, substrate or by way of other contaminated plants.
When it comes to philodendrons, here are the pests you should watch out for:
Aphids are sap-feeding insects that will penetrate the leaves of your philodendrons and suck on the sap of these plants. They’ll predominantly attack new growths on the plant.
Symptoms of aphid infestation
Aphids are small and vary in color. They can be green, yellow, light brown, red or light green. Aphids are found mostly on the underside of leaves and leave behind a sticky substance that gathers dirt and debris, causing brown spots to appear on leaves.
Treatment and control
A fast control method is to prune leaves or parts of the plant that are heavily infested. The use of insecticidal soaps, neem oil, horticultural oils, and insecticides as a last resort are also methods to treat and control an aphid infestation.
Scales are another type of sap-sucking insects that can infest philodendron plants. They have shell-like bodies and excrete honeydew. Scale insects are mostly immobile and early infestation can go unnoticed.
Symptoms of scale infestation
Scale insects look like raised bumps on the stems, leaves and new growths on the plant. Because they feed on the sap of plants, they can cause loss of vigor, yellowing leaves and ultimately, when left unchecked, they can decimate a plant.
Treatment and control
Whenever possible, try to remove heavily infested leaves and stems, then treat the rest of the plant with alcohol-soaked cotton swabs, neem oil, insecticidal soaps, or other insecticides such as those containing azadirachtin.
When using spray-on treatment methods, make sure to coat the leaves and their undersides and repeat the treatment until the infestation is treated.
Small, oval-shaped insects covered with a white or off-white, wax-like substance, mealybugs are another sap-feeding insect that can set up shop on your philodendron plants.
As they feed on the sap of the plant, they also leave behind a sticky substance called honeydew that often attracts ants.
Symptoms of mealybugs infestation
Found mostly on the underside of leaves, mealybugs have a waxy, cotton-like appearance. Plants infested with mealybugs become weak, their leaves yellow and curl.
Treatment and control
The same treatment methods that work for aphids and scale insects will work for treating a mealybugs infestation as well. Neem oil, insecticidal soap and other natural insecticides can be used to treat an ongoing infestation or prevent another one.
– Spider Mites
A type of arachnid insect, spider mites live in colonies and like the other sap-feeding insects I described above, they too attack a houseplant by feeding on its sap.
They’re very small (1/50 inch long) with oval-shaped bodies and a reddish-brown color. They’re most prevalent in hot and dry conditions.
Symptoms of a spider mites infestation
Spider mites appear as tiny red dots appear on the underside of leaves coupled with fine webbing on the leaves.
Spider mites also leave behind feeding marks on the leaves. They show up as light-colored dots on the leaves. Leaves turn yellow and with time they’ll dry and fall off.
Treatment and control
Prune away heavily infested parts of the plant and apply generous layers of insecticidal soap or neem oil. You can use other organic insecticides as well. Repeat treatment every 3-5 days until the spider mites population is destroyed.
Common Philodendron Diseases
Apart from your regular houseplant pests, philodendron plants can also suffer from diseases and deficiencies, many of which, however, are easily prevented with a few practices that I will discuss below.
Here are the most common philodendron diseases and problems to watch out for:
– Bacterial Leaf Spot
Caused by a pathogen named Xanthomonas campestris pv. Dieffenbachiae, bacterial leaf spot causes translucent spots on leaf margins that turn brown with tan or yellow halos. Spots are usually irregularly shaped.
The pathogen causing the diseases can be found in soil, it can be carried by other plants or tools that you use on your philodendrons. One way to prevent the diseases is to refrain from overhead watering.
To control the disease, you can remove infected leaves and use products that contain plant-growth-promoting rhizobacteria such as mycorrhiza.
– Bacterial Blight
Caused by the pathogens Erwinia caratovora pv. Carotovora E. chrysanthemi, bacterial blight is another potential disease that your philodendrons can suffer from.
Symptoms of the disease include very dark spots that start out on the leaves and expand rapidly to petioles. In cases of severe damage, leaves rot and fall off, leaving behind a foul smell.
Because the pathogen causing bacterial blight in philodendrons can be easily transferred onto the plant, prevention is key. Refrain from watering the plant from overhead and keep leaves and petioles dry at all times.
Biological control of the pathogens seems to be the most straightforward way to deal with the disease.
Soil amendments and organic fertilizers containing beneficial microorganisms seem to be the most efficient in controlling the diseases.
The beneficial fungi, viruses and bacteria in these products fight the pathogens causing bacterial blight.
– Tip Curl
Over-fertilizing your philodendron plants can cause tip curl and browning leaves or leaf margins. While not a disease in itself, it’s a problem that’s often found in philodendrons whose soil is over-saturated with fertilizer.
Limit fertilizing to once a month and don’t use more than the recommended dose. In fact, it’s best to dilute the fertilizer and use a weaker solution.
Flushing the soil or repotting the plant will also help if excessive fertilizer was used.
– Temperature Shock
If the temperature is not maintained at over 55 F in the room or place where you keep your philodendron, the plant can suffer temperature shock, which can exhibit symptoms that may have you believe your plant is suffering from a disease.
When a philodendron is exposed to cold, dark green or brown blotches can form between the veins of the plant.
The ideal temperature range for philodendrons is between 60-75 F. These plants are not cold resistant, let alone frost resistant and temperatures below 55 F can cause tissue damage and lead to the death of the plant.
– Mineral Deficiency
Philodendrons with various mineral deficiencies can exhibit various symptoms like stunted growth, small leaves, of V-shaped yellow marks on the leaves in case of magnesium deficiency.
Make sure you feed your philodendron with a balanced liquid fertilizer once a month during the spring and summer.
Don’t feed more than the recommended dose to prevent fertilizer burn.
How to Prevent Pests and Diseases in Philodendrons
Some of the pest problems and diseases I discussed in this article can be prevented and better managed if you integrate the following tips in your philodendron plant care routine:
- Keep humidity levels within the range needed for philodendrons to prevent spider mite infestations.
- Keep new plants ‘quarantined’ from other plants to see if any pest problems or diseases appear.
- Sanitize any tools you use for cuttings or trimming; these can carry bacteria, fungi or other diseases.
- Avoid overhead watering your philodendrons.
- Keep water off leaves and petioles.
- Maintain a good watering and feeding schedule.
- Apply neem oil or organic insecticidal sprays periodically to prevent pest problems.
- Replace the substrate every 2-3 years or whenever the plant outgrows its pot and repotting is in order.
- Isolate already infested plants so that the infestation doesn’t transfer to other plants.
- Remove heavily infested stems or diseased leaves as a quick fix to an infestation or infection problem.
- When infestation is severe, you can destroy infested plants and apply insecticidal soap or neem oil on your other plant as a precaution.
- Keep philodendrons away from cold drafts or AC vents and maintain optimal temperature to prevent temperature shock.
With these quick and easy-to-follow tips, I am confident you can significantly reduce the incidence of pest problems and diseases in your philodendrons.
When caught early and addressed properly, several pest problems and leaf diseases
Because of their small size and location (underside of leaves), many pest problems affecting philodendrons can go unnoticed. Periodic inspection of the leaves but also occasionally spraying the leaves with insecticidal soap or neem oil can often help prevent pest issues.
Always make sure you’re correctly watering philodendrons, maintain a good feeding schedule and offer optimal temperature and light conditions to grow strong, resilient plants.