By Emma Kelt, | Updated 17/01/2024

Related: What are the dots on the back of my Piper plant leaves?

Philodendrons are beloved indoor plants known for their lush foliage and easy-care nature. However, like any living organism, they can occasionally develop issues that might concern plant collectors. One common problem is the appearance of brown dots on their leaves. In this article, we'll explore several different types of brown dots and spots on philodendrons: rust spots, water burning from misting, fertiliser burn, and extrafloral nectaries. We'll discuss what to look for, how to treat rust spots, and understand the purpose of extrafloral nectaries.

Fungal leaf spot, Leaf burning, & Extrafloral Nectaries

📷 Fungal leaf spot on a Philodendron

Rust Spots on Philodendrons

Fungal leaf spot disease or rust spots are one of the most common leaf issues seen in philodendrons. These spots appear as small, reddish-brown dots that can gradually grow in size. They are caused by fungal infections, primarily belonging to the Pucciniales order. To identify rust spots, look for clusters of dots on the upper and lower surfaces of the leaves.

Treatment: If your philodendron shows signs of rust spots, it's important to address the issue promptly. One effective treatment is to use a copper-based fungicide spray. Follow the product instructions carefully and make sure to treat all affected areas. Additionally, ensure good airflow and avoid overhead watering to prevent the recurrence of rust spots.

📷 Leaf Burning from misting on a Philodendron

Leaf Burning - Misting

Many plant owners believe that misting their philodendrons with water will increase humidity and promote healthier growth. However, misting alone does not significantly raise humidity levels, and excessive moisture can lead to water burning. Water burning appears as brown spots surrounded by yellow rings on the leaves. These spots occur when water droplets magnify sunlight and cause damage to the leaf tissue.

Prevention: Instead of misting, consider alternative methods to increase humidity for your philodendron. Placing a tray of water near the plant, using a humidifier, or grouping plants together can create a more humid environment without the risk of water burning.

📷 Fertiliser burn on a Philodendron

Leaf Burning - Fertiliser Burn

Fertiliser burn refers to the damage plants experience when they are unable to process an excess or improperly applied fertiliser. It commonly occurs when too much fertiliser is used, or when plant food is applied to wet foliage. The ability of a plant to process nutrients is influenced by its overall health and environmental conditions, which also play a role in its recovery from excessive fertiliser feedings. When plants can't process fertiliser efficiently, the salts present in the fertiliser draw out moisture from the roots through osmosis, dehydrating and ‘burning’ the plant. This is similar to the effect of drought on plants. In the case of overfed houseplants, the initial signs of fertiliser burn typically appear as yellow or brown leaves. Over fertilisation of philodendrons often results in brown leaf edges and tips, as excessive salt content in the soil hinders root absorption of water and oxygen.

Treatment: To address this issue, it's essential to flush the soil thoroughly with water to leach out excess salts and restore the plant's nutrient balance. Additionally, adjusting the fertilising routine and ensuring proper watering practices will promote the plant's recovery and prevent further damage. In some cases, depending on the level of stress your plant is experiencing due to fertiliser burn, more drastic measures may be required. One possible solution is to carefully remove the top 15cm of the growing medium and replace it with a fresh mix. Alternatively, you might consider repotting the plant altogether. However, it's important to note that these actions can further stress the plant and potentially cause additional damage. Despite the potential risks involved, if the plant is severely affected and there are no other viable options, this approach may be necessary to give the plant a chance to recover.

Extrafloral Nectaries on Philodendrons

Extrafloral nectaries are glandular structures found on the leaves or stems of some plants, including certain species of philodendrons. They produce sweet, sticky substances known as nectar, which attract ants, wasps, and other insects. These insects serve as bodyguards, protecting the plant from herbivores that may harm it.

Identification: Extrafloral nectaries on philodendrons typically appear as tiny, shiny dots on the surface of leaves. They are usually translucent or slightly yellowish. Unlike rust spots or water burning, these dots are not associated with any disease or damage to the plant. Instead, they are a natural feature of certain philodendron varieties.

Understanding the different types of brown dots on philodendrons can help plant collectors diagnose and address issues effectively. Rust spots caused by fungal infections can be treated with copper fungicides, water burning can be prevented by avoiding excessive misting, and you can flush your medium with water if you over-fertilise. On the other hand, extrafloral nectaries are harmless and signify a natural feature of certain philodendron species. By being observant and taking appropriate measures, you can keep your philodendrons healthy and thriving for years to come.

Remember to provide your philodendrons with the right care, including appropriate lighting, watering, and humidity levels, to ensure their overall well-being. Happy Planting!

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