Is this the start of blight?

[solanaceae]

Have you been feeding them tomorite?

Tomorite only has Nitrogen, Phosphorus and Potassium in its list of nutrients. Whilst these nutrients are helpful for tomato plants, it doesn't include magnesium which is needed for healthy foilage of the plant.

If you are growing plants in the ground then tomorite is fine to use as your feed, because there's always an excess supply of soil and, therefore, magnesium around for it to take advantage of. On the other hand if you are growing your plants in pots and using tomorite, then at this time of the season there is no surprise that your plant is showing a magnesium deficiency because there just isn't enough magnesium in your little pot of soil for your plant to take up.

You could use epsom salts to remedy the problem (seems to work for plenty of people on here I've read, though a build up of a salt in the soil is never good in the long run), or you could use a fertilizer that has the NPK formula AND magnesium. Chempak's 'tomato food' is one of these that I use and it helps a lot I've found.

[gardening_gal]

Have you been feeding them tomorite?

Tomorite doesn't have magnesium in its list of nutrients, only Nitrogen, Phosphorus and Potassium. Whilst these nutrients are helpful for tomato plants, it doesn't include magnesium which is needed for healthy foilage of the plant.

Yes I've been using Tomorite and what you say now makes perfect sense to me, thanks for explaining. I didn't realise Tomorite lacked magnesium, I thought it was a good all rounder. (The plants are in growbags btw.)

Still not sure why the back of the plant seems more affected mind, or why the top leaves seem worse than say the middle leaves but maybe something else is adding to the equation too. I'll change the feed asap.

Thanks everyone, appreciate the help as ever.

[Penellype]

I didn't realize tomorite didn't contain magnesium either. The one that I have been using is a very old large bottle of Bio tomato food, which does contain magnesium, but I haven't seen it in the shops for ages.

[NatalieCooke]

I bought some Epsom Salt from Boots £1.99 a tub. I add it to the water once a week and spray the leave everyday. It's hasn't helps the leaves already affected but all the other leaves look great.

[Penellype]

A few pictures that some people might find helpful, all taken today of tomatoes in various places. You will see the symptoms much better if you click on the photos to view them.

1. Not blight - Magnesium deficiency in a plant in a small pot in my sitting room

Note the purplish colour of the affected leaves, which is always between the veins, and the green stem. Variety is Shirley.

2. Not blight - brown spots on leaves.

These spots are mostly on the lower, yellowing leaves, but there are some, brown with yellow margins, on leaves higher up. Note there is no fuzzy whitish bloom on the inderside of the leaves, and the stems are green. The plants have been like this for a couple of weeks at least. Variety Sungold, outside. I find Sungold tend to do this.

3. A definite case of late blight. (Sorry about the colour of the photo - the bed was in quite deep shade when I got there).

These are plants at my friend's house which started showing signs of blight yesterday. Note the greyish brown patches on the leaves and the black marks on the stems. The whole thing has a mucky, unhealthy look to it, and it is spreading rapidly through the plants. Although the fruit in the picture is still green, even if you pick this and bring it indoors it is infected and will rot rather than ripen. Variety Chocolate Cherry, outdoors. I have had no ripe fruit at all from this plant. Belle and Sungold, planted in the same bed, are showing the same symptoms.

[gardening_gal]

Thank you Penellype, it's helpful to see the different types of damage alongside each other. I'm happy to see that my plants don't look like the blight pictures.