Anthracnose (fungus – Glomerella cingulata): Leaves dry out and cling to the stem. Twigs are blighted and cankers are formed at the base of the main stem. cankers may be spotted with pinkish pustules. The bark and wood of diseased portions become brown and the bark on the cankers may split, exposing the wood, Death occurs when the cankers completely encircle the twigs or stems. The following varieties are resistant: Amur privet, L. amurense; Ibota privet, L. ibota; regal privet, L. ibota regelianum; and California privet, L. ovalifolium. For climates in which winter killing is not a factor, the California privet is preferred for planting.
Green Scurf (alga – Cephaleurus virescens): Green scurf or algal leaf spot appears on twigs and limbs. Spray or dust with a copper fungicide recommended for general use on ornamental plants being careful to cover the underside of the leaves. Add a spreader-sticker to the spray.
Leaf Spots (fungi – Exosporium concentricum, Cercospora adusta, Phyllosticta ovalifolii): Brown or dark colored spots occur on the leaf. Generally not serious. Usually occurs during very rainy seasons or more frequently in overcrowded, poorly aerated plantings. Most prevalent just before normal fall of old leaves.
Sooty Mold: A blackish growth occurs on the leaves. Commonly follows white fly infestation. Control white flies.
Crown Gall: (See the section on Crown Gall)
Chlorosis: See section on Chlorosis.
Cotton Root Rot: (See the section on Cotton Root Rot)
Mushroom Root Rot: (See the section on Mushroom Root Rot)
Root Knot Nematode: (See the section on Root Knot Nematodes)
Winter Injury: See section on Winter Injury.
Gall (fungus – Phomopsis sp.): Galls develop rapidly reaching a diameter of one and one-half inches within five and one-half months. These galls are commonly mistaken for bacterial galls. Prune out the galls. Pruning shears need not be sterilized as they will not infect a pruning cut.