Chlorosis is a common micronutrient deficiency that causes the leaves of trees to become yellow and in severe cases causes the foliage to brown and die. In southern and eastern Wisconsin, it typically affects white oaks, pin oaks, white pine, red maple and birch. Chlorosis is caused by either a lack of nutrients (typically iron and manganese) in the soil or the inability of a tree to absorb the nutrients through its roots. Trunk injections with liquid iron and treatments of Bio Pak plus root stimulant with added iron and manganese helps trees to correct the chlorosis by providing the needed micronutrients and increasing the tree’s ability to absorb them. The key to maintaining the color and health of your trees is treating chlorotic trees as soon as you become aware of the symptoms. Keeping trees on a regular fertilizing schedule can greatly help to reduce the chances of trees becoming chlorotic.