Tomato Purple Leaf Disorder (TPLD)
 

Does anyone have any information about how to deal with this seemingly new tomato issue? I do not have it myself, but an online gardening friend believes she has signs of this on some of her plants in her garden this year.

Many claim it is phosphorus def but it is a totally different beast.

Anyone?

I have the same problem. and have read it was a lack of phosphorus also. I added phosphorus around the plant today. I guess I'll find out in a couple weeks if it works or not.

Phosphorus deficiency shows first as purpling on the bottom of the leaf surface, where Tomato Purple Leaf Disorder shows on the top of the leaf surface.
Have the plant pathologists ever figured out what the cause of TPLD is? The last I heard they suspected it was cause by a virus since no other pathogen was discovered.