Help Me!!

i have a month old plant that has been doing fine till about a week ago.the leaves started turning brown and has powder all over it.its been in a room with 4 other plants and its the only one with this problem.i have it in regular soil and under a 123watt light.

Dont put that one back in its moldy. You must have a damp growing environment, get a hygrometer and get the humidity down to 40-50 % and maybe a bigger light and a sulfur burner.

i was given this stuff called DEFENDER.it says it safe to use on roses and other garden flowers.would it be safe for my plant?it spose to controls and kills black spots,powdery mildew and rust.