Brown edges along the leaves of an apple tree indicate a health problem. A variety of factors influence the health of an apple tree--from pests and disease to the planting location of the tree. Identify the cause of brown leaves to keep the tree from sustaining further damage.
Drought is a problem that causes the leaves of many plants to turn brown at the edges, starting at the tip and curling inward as the tree loses water. A lack of water forces the tree to return to a dormant state, as it can no longer process nutrients or sunlight without moisture. To keep the leaves green, water apple trees at least once a week, especially during hot, dry periods of the growing season.
Pests like aphids, caterpillars and slugs feed on the leaves of apple trees. These pests begin feeding at the edge of the apple tree's leaves, leaving wounds that eventually turn brown as the leaf dies. Serious pest infestations can lead to curled or dropped leaves and weaker growth for the apple tree. Apply pesticides to the apple tree as needed during the growing season to keep the leaves from being damaged.
A lack of proper nutrients in the soil leads to discoloured, weak leaf production or the appearance of discolouration around the edges of the leaves. Some of the most important nutrients for apple tree leaf health are zinc, magnesium, iron, phosphorus and potassium. Spray the tree with zinc in the spring to keep it . Fertilise the tree in early spring to provide the leaves with vital nutrients.
Cedar-apple rust, a fungal disease that affects juniper and apple trees, causes brown spots to appear on the leaves. As the fungus spreads, the leaves turn brown or yellow and eventually die. Apply a fungicide to the apple tree to control the spread of cedar-apple rust fungus and remove any fallen leaves or branches from the tree's growing area.