Potassium Deficiency
When plants are deficient in potassium, symptoms usually appear first on older leaves as yellowing along the leaf margins that progresses to brown, scorched, or necrotic edges, often accompanied by leaf curling and reduced plant vigor. Potassium deficiency can be confused with magnesium deficiency, which also affects older leaves but shows more distinct interveinal yellowing, and with nitrogen deficiency, which causes more uniform yellowing of entire older leaves rather than marginal scorch
