How to treat rust spots on fiddle leaf fig plant?

huongtrinh

Hi community, 

I have noticed what I suspect as thrips on my fiddle leaf fig plant. The new leaves seem to have more of these white spots than the mature leaves. Is anyone able to confirm whether these are thrips and what is the best way to treat them? 

I also have noticed some of the leaves have a lot of red spots. I have read up about them and they can be caused by overwatering or pest infestations. I'm wondering if anyone can let me know what these red spots might be, that would be much appreciated. 

Thank you in advance.White spots on a young leaveWhite spots on a mature leaveRed spots on a mature leave

EricL

Hello @huongtrinh 

The leaf in the image has characteristic dark, rusty-looking spots that often indicate Fiddle Leaf Fig Rust (a fungal issue) or Edema, which is a physiological disorder. Given the combination of red spots and the potential thrip infestation you mentioned, it's likely a mix of the following factors. Edema (Water Imbalance) can occur when the plant takes up water faster than it can use or evaporate it, causing cells to burst and leaving small, rusty-red or brown spots. 

This is common in overwatered fiddle leaf figs, especially if the soil is compacted or the pot lacks proper drainage. Fungal or Bacterial Leaf Spot is another possibility, as some fungal or bacterial infections can cause similar spotting, often spreading in humid, poorly ventilated environments, especially if the leaves get splashed during watering. Additionally, Thrip Damage can cause tiny scars and discolored patches as the insects feed, though the red coloration itself is more likely a secondary issue. Thrip damage usually appears as silvery or speckled patches rather than distinct red spots.

To address these issues, first check for thrips by using a magnifying glass or shaking the leaves over white paper to confirm their presence. If present, spray with an insecticidal soap or neem oil every 7-10 days, ensuring thorough coverage of the undersides of the leaves. Next, improve drainage by using a well-draining potting mix and ensuring the pot has adequate drainage holes. 

Consider switching to a cactus or succulent mix if your current soil is too dense. Adjust watering by allowing the top 2-3cm of the soil to dry out before watering again, which helps prevent both root rot and edema. Increasing airflow by placing the plant in a brighter, well-ventilated spot, away from direct air conditioner drafts, can also reduce fungal spread. If a fungal issue is suspected, remove the most affected leaves and spray the remaining foliage with a fungicide like Yates Liquid Copper or Eco-fungicide to reduce further spread.

If you need further assistance, please let us know.

Eric