Help! I rescued this corn plant from Lowe’s (was on their discounted rack and very sick) last summer. Since the we’ve been through nursing back to health to bugs a few times. Now I see these brown spots beginning a few different leaves and I’m not sure what it is and how to treat. I was spraying with neem, once that was gone I started with peppermint and water (read that worked) and finally started with a systemic granular mix for all sorts of insects. Anything else I can try???