My peperomia obtusifolias have tiny reddish brown dots on the leaves (top and bottom). Any idea what it is? They don’t move and i can’t wash or scrape them off. Leaves are also dropping.
Dear gardener, thank you for contacting the Toronto Master Gardeners. I am sorry to hear about your Peperomia obtusifolia ailment.
It is a bit difficult to properly identify the issue without a photo or further information but I will try to guide you narrow down the possible culprits. Are the brown spots soft or crispy; sunken or raised? Have you recently purchased this plant or brought it from outside? Are the brown spots all over the leaf or concentrated around the tip?
Overwatering and poor drainage often causes Oedema (leaves take up more water than they can transpire). It results in the excess water rupturing the cells, particularly on the underside of the leaves, leading to blistered and scarred-looking patches. This problem can be prevented with good air circulation, good drainage and allowing your plant to dry between waterings.
Underwatering: if the brown spots are concentrated around the edge or tip of the leaves, dropping and the soil feels very dry, then this could be the cause.
Brown spots and dropping leaves can also be a sign of Thrips. These tiny insects (3mm long) are often missed and we see their damage before we see them. Often it only takes one female thrips to start the damage. It is a common occurrence when plants are brought inside after the summer outdoors or when recently purchased.
Female thrips will insert their eggs into the plant’s foliage and stems. When the eggs hatch, the nymphs (which are even tinier than the adult) start feeding on the plant. Then, the fully grown nymphs will drop to the soil where they will undergo the pupal stage and transform into adults which will fly back up to the plant and repeat the cycle.
Fungal diseases: there are several fungi that can create brown spots:
- Cercospora leaf spot: raised brown or black spots on the bottom of the leaves;
- Phyllosticta leaf spot: black or dark brown rings that are usually spread across the whole leaf;
- Rhizoctonia leaf spot: mushy dark brown or black spots can be found anywhere on the plant.
Lastly, Fluoride in tap water can sometimes cause brown spots. This can be solved by letting the water sit in the watering can for 24 hrs before applying.
I realize that the above may be a bit long but the more you can narrow down the root of the problem, the easier it will be to solve and hopefully save you Peperomia.
Please feel free to contact us if you have further questions.