Help - Dead Patches
 

Help!
Patches of my garden look like they have been sprayed with weed killer.
I thought at first that I had accidentally put some in my hand insecticide
spray. But I've changed the fluid and more patches have appeared.
The most effected plants are nasturtiums but a six foot high clematis in a
two foot high pot and some lupines have also died. By one set of plants even
the grass border is dead.
It's Scotland so it's not lack of water :-)
The rest of the garden is thriving around the dead patches.
One strange thing I noticed is that the flowers of blue lobelias by the
patches have turned white.

I thought of cats, dogs, foxes spraying but there is no smell.
Can an OD of insecticide kill off plants? - Though there is no correlation.

Any ideas?

Slatts