Iron deficiencies or disease can result in browning leaves on new blueberry plants. These diseases often can be fatal to the young plants. Even if the plant survives, the disease can result in limited fruit production and stunted growth.
Several fungi, including blights and stem cankers, turn leaves and stems of blueberry bushes yellow or brown. Lesions may appear on the plants. Sometimes, dead branches with reddish-brown leaves on them can be seen, an indication the fungi is killing the plant.
Phytophthora root rot often occurs on blueberry bushes with poor-draining soil. The leaves of affected plants turn reddish-brown before the branches and stems become defoliated.
In severe cases, iron deficiency causes leaves to turn reddish brown. The plants require iron to thrive, but soil with too much acidity limits their ability to obtain the nutrient. Adding iron chelate to the soil or leaves helps to correct the problem.
Pruning helps increase sunlight penetration to the plant, helping to dry out the fruit and foliage so it doesn't experience fungi problems. Blueberries also require highly acidic soil for consistent growth, with the soil draining well to prevent root rot.