How to treat brown spots on lemon leaves?

[Andrew12]

My lemon tree has been in a big pot for 2 years. I fertilize it quite regularly and it gets a daily drip on a watering system

 

 

Recently it started losing leaves but has now sprouted new leaves with brown spots around a tiny white dot at the center of the brown spot. The brown area is not raised from the leaf service itself. See photos. Help!!

[EricL · Accepted solution]

Hello @Andrew12 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your lemon tree.

Your lemon tree appears to be dealing with an issue that could be caused by citrus leaf miner or a fungal infection, given the brown spots with tiny white dots at their centres. Citrus trees in pots are more prone to stress, which can make them susceptible to pests and diseases. Here's how to help your lemon tree recover:

First, ensure the tree isn't being overwatered - while a drip system is convenient, excessive watering can lead to root issues that show up as leaf problems. Check the soil moisture before each watering, ensuring it dries out slightly between waterings.

The symptoms described are commonly associated with pests like citrus leaf miners or fungal diseases such as citrus scab or anthracnose. For pests, use a product like Eco-Neem or Pest Oil, these treatments help smother pests and discourage new infestations. For fungal issues, treat the leaves with a fungicide such as Yates Liquid Copper or Eco-Fungicide.

Trim off any heavily affected leaves to prevent further spread, but avoid heavy pruning, as new growth can attract more pests. Feed the tree with a citrus-specific fertilizer, like Osmocote Plus Trace Elements for Citrus & Fruit, to boost its immunity. Additionally, apply a liquid tonic like Seasol to reduce stress. I also suggest having a quick look at this guide - How to diagnose a sick plant by @Noelle. 

Lastly, keep the tree in a sunny spot with good airflow, and monitor new growth closely. With these measures, your lemon tree should start to recover.

Please remember to wear personal protection such as gloves, goggles and a mask when using chemical sprays.

If you need further assistance, please let us know.

Eric

[robchin]

HI @Andrew12 

Some good advice below from @EricL 

I would ask 2 other questions:

1) Is the pot big enough? Lemon trees need at least a 50cm pot when established. 

2) Are you using a fertiliser for highly fruiting plants? Plants that fruit a lot need a balanced fertiliser with phosphorous and potassium, lighter on nitrogen (once established). You can use any fertiliser designed for fruiting trees - but this one is specific to citrus: Scotts Osmocote 500g Citrus and Fruit Controlled Release Fertiliser - Bunnings Australia