b'Growing in a medium that is too wet results in a lack of oxygen, which causes stagnation in uptake. A high content of zinc, manganese or magnesium in the soil or substrate also leads to an iron deficiency. A shortage can be eliminated by spraying ferrous foliar fertilizers over the crop. Lack of ironExcess symphomsAn excess of iron can lead to a lack of manganese.The deficiency diseases are very similar. Manganese deficiency is also noticeable on the somewhat older leaves.ManganeseManganese plays a role in photosynthesis, protein metabolism and cell division. This means that it can move somewhat in the plant. The plant absorbs Mn2 +. In some enzymes it can replace magnesium. Manganese strengthens the cell walls.At a pH 6.5, too little is absorbed by the plant and at a too low pH, a lot of manganese dissolves, making it phytotoxic. The sensitivity depends on the variety.119'