Copper actually plays a surprising amount of roles within a plant system. It is part of enzymes essential for the formation of chlorophyll. It also plays a role in lignin synthesis, photosynthesis, plant respiration and metabolism of carbohydrates and other plant proteins. It even plays a role in terpene enhancement, color intensity and flavor profile. It is an immobile nutrient so deficiency occurs in new growth. The new growth loses sheen and sometimes even wilts. In severe cases, the apical meristems even become necrotic and die. There are a few things that can cause Copper deficiency. Not only can an extremely high pH cause Copper deficiency, but excess Phosphorus or Potassium can as well.