Hello!
I’ve noticed my lemon tree has developed a kind of rot on the leaves as well as some of the smaller branches have started rotting and dying. I’ve been told it could be zinc deficiency but it looks like rot to me! Any help is greatly appreciated!
Lemon trees like well drained soil and don't do well in poorly drained soil. The last 6 months have been very wet and even soil that was draining well is over wet. It sounds like that your tree is suffering from too much water. I don't think it is Zinc deficiency as this tends to show as mottling between the veins of the leaf. Prune away all the damage branches to encourage new growth in spring.