HelpfulGardener.com

Hi
New to the forum and hoping you could help me out.

Set up a Flower tower in the summer with lovely little flowers.But just over four days most of the leaves have fallen away and I can see bare twigs,still green. The plants nearby are fine.
Have used a bug spray at least three times this season and eggshells for the snails.

Can you tell me if this is a pest or a disease and if I can still sav them some way.

Two pics attached. Thank you and Regards.

They look like Impatiens...Bizzie Lizzies.
Over here we have suffered for a couple of years with Downey mildew disease on these lovely little plants, often causing complete death to whole beds of plants. For a while they went completely out of fashion ...but new vars are much more resistant to the problem apparently.