Spots On Lemon Tree

Question

Hi I have recently bought a full grown lemon tree (About 2.3 meters tall) which is now placed outdoors in my balcony in a large fiberglass pot. It gets about 11 hours of (indirect) sunlight per day under the shade of the balcony. The leaves have been falling rapidly and many of them have developed spots (see picture attached). Can I get help to understand what the problem is, and how I can solve it? Thank you! I am also having trouble figuring out how to water it as it is a deep pot and the surface gets very dry within a few days of watering (I live in very warm Singapore), and I understand over-watering is a very bad idea. I bought a water meter and the meter goes to 3 out of 10 literally 3-4 days after an intense watering, so I am not sure how to take the reading. Should I wait for it to go down to 1 of 10? Any advice will be appreciated!

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Answer 1

This type of damage can be seen when the plants acquire certain insect infestations. Spider mites and white flies come to mind, here.

These articles will help:

https://www.gardeningknowhow.com/plant-problems/pests/insects/spider-mite-treatment.htm

https://www.gardeningknowhow.com/plant-problems/pests/insects/spider-mite-control.htm

https://www.gardeningknowhow.com/edible/fruits/lemons/common-lemon-tree-diseases.htm

Here is an article to help you with the care of the tree in container:

https://www.gardeningknowhow.com/edible/fruits/lemons/growing-lemon-trees-containers.htm

Finally, this article will help you to use a watering probe, properly:

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm