[Richard Faulk]

I have tomato plants that the leaves are turning yellow form the main stock out. Can anyone tell me what is causing this? Pictures posted.
http://www.veggiegardener.com/forum/attachment.php?attachmentid=367&d=1428884577&thumb=1&stc=1
http://www.veggiegardener.com/forum/attachment.php?attachmentid=368&d=1428884579&thumb=1&stc=1
http://www.veggiegardener.com/forum/attachment.php?attachmentid=366&d=1428884576&thumb=1&stc=1

 

[Timbertodd]

Richard, this might be your culprit.
http://pnwhandbooks.org/plantdiseas...ulentum-wilts-fusarium-wilt-verticillium-wilt

 

[JosephVe]

I think that it is Alternaria Alternata - a fungus that can cause plant leaf spots and cankers. These can eventually kill the plant. So will be better to take remedial actions. You can spray fungicide on the plant. It can lessen the problem. Make sure that you plant them apart in the future. Also make sure that you don't water them from overhead.