Sweet williams problems
 

Hi
I am trying to find out what is the cause of the
problem with my sweet william plants.
It starts of as a small dark spot under the leaves,
then expands to a brown blotch breaking through
to the top of the leaf spreading and finally destroying
the leaf and plant.
This is happening to old saved seed and also fresh
bought seed.
I would be most gratefull for any suggestions as to
the cause as asking local gardeners has drawn a
blank.