I have Brown spots on lemon skins of the majority of lemons on my tree
Fruit and Citrus • Pests
These sunken and blackened lesions on your fruit look very much like the damage caused by the feeding of a piercing-and-sucking insect, probably a "true bug" such as the Bronze Orange Bug. For the control of Bronze Orange Bug on citrus try Yates Nature's Way Citrus & Ornamental Spray (Pyrethrum Plus Oil Pest Spray). Controls a wide variety on insects pests on many edibles and ornamentals. For all other bugs on citrus we recommend hand removal then place in a bucket of soapy water. Just make sure you are wearing goggles, gloves and a long sleeved shirt as they can projectile an acidic smelly secretion.
Answered: 13 Aug, 2021