This is a strange one, not really sure what the problem is here.
Can I start by just checking that the poorly Solanum has drainage holes in the bottom of the container?
If the container does have good drainage we need to move on, firstly remove all of the dead leaves from the container, then if the two Solanums are close together move them far apart as you want to avoid the possibilty of airborne disease moving from the poorly plant to the healthy one.
If you can, remove the poorly Solanum from it's container and inspect the rootball, any sign of any pests? e.g. larvae or grub-like creatures.
Next examine the trunk/stem of the plant, any visible damage? If the plant is a standard, the method of propagtion may have been grafting. (The main stem and crown are two different plants) Where the main stem meets the crown there may be a point where the crown looks like it has been joined to the stem artificially, if there is, does it look a strong union?
If all of these checks are OK I think I would wait until next spring, then cut all of the shoots/branches hard back on the crown and see if you get a vigorous, healthy response.Statistics: Posted by gardening_guru — 18 Aug 2010 21:35
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