b'CopperCopper ensures that stems are lignified and is essential for various enzymes that make proteins, vitamins and sugars. A more intense odour and colour is also caused by copper. Copper is immobile and the defects are therefore first manifested in the youngest leaves.Deficiency symptomsThe typical symptom of copper deficiency is the spherical leaf position and a slight yellow discoloration between the veins of the young leaf. At a more advanced stage the leaf margin turns brown. New leaves are smaller and lose their shine and may eventually dry out. The top of the stem dies and the growth of the side shoots is inhibited. The plants have a compact growth and the colour of the flowers is lighter than normal.Excess symptomsAn excess of copper is phytotoxic and often occurs in combination with an iron deficiency. An excess of copper impedes iron absorption.MolybdenumThe last essential element is molybdenum. This element cannot be applied in chelated form either. The plant needs the least of these. This is involved in the formation of various essential enzymes. Some prominent enzymes with molybdenum are involved in the conversion of nitrate, sulphate and phosphate and in the energy supply in the plant cell. Molybdenum is difficult to absorb at a low pH.Excess of boron123'