Hi there
I planted a meyer lemon around 6 months ago and the older, lower leaves are producing mottled yellowing/also some leaves with the V-shape yellowing. This yellowing is slowly rising higher towards the younger leaves.
The tree is producing fruit which is starting to ripen, and also flowering at the moment.
So far I've added epsom salts a couple of times to the soil and watered that in, with no improvement.
I then did a foliar spray of trace elements, but have not repeated this as the label advice is to not apply while flowering.
Image attached. Any advice appreciated!
The V shaped yellowing of the leaves is a classic indicator of Magnesium deficiency. Because magnesium moves freely through the plant, the deficiency tends to show on the older leaves first and gradually move up the plant. You are doing the right thing by watering in Epsom salts. It is worth noting that over use of a fertiliser high in Potassium can induce Magnesium deficiency. Another thing that is worth looking at is the pH of your soil, Magnesium deficiency seems more prevalent in acid soil, if your soil is very acid you can adjust the pH with a lime base product.