Solution: Potassium is an important macronutrient that everyone needs. Potassium shortage symptoms include mottled chlorosis and necrosis, which appears first in older leaves, loss of apical dominance, dieback, bushy habit, shorter internodes, lack of cambial activity, plastid disintegration, and premature mortality, among others. Yellowish edges appear in leaves deficient in Nitrogen, Magnesium, Potassium and iron.