Micronutrients are chemical elements that are essential to a tree's normal growth and development , even though only a few atoms out of every million are needed. There are 8 known micronutrients. Iron and manganese are the most important for ornamental trees. Crop trees have special needs not discussed here.
Different micronutrients have different functions.
Many commonly affect specific cellular reactions such as chlorophyll synthesis, nitrogen fixation, and respiration. With extreme deficiency, the leaves become completely yellow. Conifer needles turn yellow-green. Also, manganese is now recognized to be very important. A number of other species show reduced vigor and health.