I've got two Stupice Heirloom tomato plants. Both were bought as siblings and planted 2 months ago; both grew nicely and started bearing fruits (none of which is yet red). The plants are kept in a cone shaped cage (not too effective, I know, the plants started flowing over the cage's top now).
The plants are 6 feet apart, placed in a 1 ft raised bed with a total of 2ft dug and mixed soil. the soil is Miracle Gro "Organic Choice" mixed with the local soil (which is clay). The plants are subjected to similar temperature, wind and sun. The local temperature where I live (Mountain View, CA) have recently dropped to 42-60.
I've noticed that one of the bushes started having black-brown patches along the leave vines and branches, leading to the leaves and branches to decay. When this occurs on one of the heavier branches, this eventually leads to the collapse of the top of the branch. The other plant doesn't appear to suffer from any of these problems.
Any suggestions on the cause of this and what I should do? Sorry in advance if this is a FAQ - please forward me to a relevant thread if so...