Charles Packer said:

My wife would like to know what ails
her snap beans. The tops of the leaves
look like some graffiti artist cleaned
out the nozzle of his white spray can
in the vicinity.
http://cpacker.org/a1.jpg
shows her row of seven pots.
http://cpacker.org/a2.jpg
is a close-up of a couple of the
worst-affected leaves.

Looks like spider mite damage to me, too.

Been hot and dry where you are?
--
Pat in Plymouth MI ('someplace.net' is comcast)

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)