My potted lemon tree has been losing leaves. The leaves exhibit a pattern of lighter blotches at the edge of the leaves, which I suspect may be due to a magnesium deficiency, but also a strange pattern of dry spots on the upper surface of the leaves, which I don't know what to attribute to.
What could be causing these? I've attached a couple of images.
Late effects of the frost. If it survives, Nov 20 or whatever the date for your area you need to start covering it. If its so big and you cannot cover then wrap the trunk at the least.
FYI I am also in 9b. Widespread frost starts Nov 20th and don't think its the 32 degree thing because of radiational cooling (cold air being more dense than warmer air with the ground loosing heat absorbed during the day) which has been documented at 42.
Citrus tree's are micronutrient hogs. The micronutrients are manganese, zinc, iron, copper, boron, molybdenum, chlorine and nickel. A Citrus based fertilizer is in order. Magnesium turns leaves yellow
