Nutrient deficiency?

[Thongmas]

I seem to get this same looking leaves every time I grow tomatoes. Could anyone shed any light on what deficiency it is? I was thinking magnesium but I've read somewhere that it's quite rare. What could I be doing wrong? I wanted to post on here before I attempt to spray any epsom salt spray on the leaves incase it's not an Mg issue, thanks in advance

[quanglewangle]

Slight curl I would say is due to cold overnight. Brown spots could be septoria fungus, but I have no personal experience of of it.

[Thongmas]

It probably won't drop under 10 degrees as it's in a polytunnel but I'm only guessing as I don't live here. Many of the other tomatoes look great but these Super Sauce F1's I'm doing for the first time look quite stressed.

[Thongmas]

It was the first photo on this page that made me think it's an Mg deficiency

https://www.rhs.org.uk/prevention-pr...t-deficiencies

[Jungle Jane]

I think Epsom salt would help but there is magnesium in tomato fertiliser too. I used Epsom salt on one of my plants a while ago for the same thing but I watered the soil with a spoonful dissolved into water.

[Penellype]

In my experience it is extremely difficult to prevent magnesium deficiency in tomatoes grow in containers, even with regular feeding. Mine always get it on the lower leaves, but it doesn't seem to do much harm. Give them a feed, but don't expect those leaves to recover because once they develop the purple spots they are there to stay. Magnesium is one of the elements in chlorophyll, the pigment that makes leaves green. My guess is that if they are short of magnesium the tomato plants extract it from the lower leaves to make new leaves with, and the purple colour is the other pigments in the leaf (this is what happens with autumn leaves that turn red).

Many people cut off the lower leaves anyway when the plants get big, to improve ventilation. I don't like doing this as it wounds the plant, creating an entry point for disease, but others disagree.