Magnolia spp.
Leaf Spots (fungi – Coniothyrium sp., Epicoccum sp., Glomerella sp., Phyllosticta sp., and Septoria sp.): Various sized leaf spots generally developing in late fall and early spring. Generally cause little damage.
Algal Leaf Spot (alga – Cephaleuros virescens): Forms a velvety coating with reddish-brown hair-like structures on the underside of the leaves. Occurs mainly in the Gulf Coast area. Causes little damage but treatment with fungicides may be required in some cases.
Leaf-Shedding: Magnolia will begin dropping leaves in November and continue until early spring. This is a natural phenomenon and the degree of leaf drop will depend upon genetic as well as physiological factors affecting the tree. Some trees may be completely denuded before new foliage comes out.
Wood Rots (fungi – Fomes sp., Polyporus sp., Daedalea ambiqua): Rot of heart wood. Colors range from white to black, may also be green or red or brown. Lines of infection are conspicuous. Conks may be formed on main trunk near soil line. Avoid wound. Infected portions may be removed by tree surgery.
Cotton Root Rot: (See section on Cotton Root Rot)
Root Knot Nematodes: (See section on Root Knot Nematodes)
Chlorosis: (See section on Chlorosis)
Winter Injury: Some trees that harden off gradually in the fall can take temperatures as low as 0oF and show no damage. Other individuals are hurt easily if temperatures commonly get below 15oF. Killing of leaves and shoots can be extensive. Winter drought coupled with low temperatures can cause extensive die back or death.
