Deficiency -Epsom Salt

You can make a foliar spray. Don’t spray it until after lights out because water droplets will act like a magnifying glass and burn your leaves. Keep your solution under 200 PPM. I see you have Ed Rosental’s book. The majority of your questions are answered in that book. Owning the book doesn’t magically make you a better grower. Read the book. Understand the book. Apply what the book says. There’s a full section on nutrients and deficiencies and how to rectify those problems.