What Is Wrong With My Cork Oak?

Are there any perfectly round, small entry-holes in trunks and primary branches?

Are the leaves small, discolored, and drop early, clusters of honey-colored mushrooms may sprout at the base of the plant?

Do the leaves have any small circular or irregularly shaped dry spots that are gray to straw in color?

Are there any reddish-brown streaks on the outer and inner bark, as well as gum or dark sap oozing from the diseased area?

Are there any discolored, sunken cankers on twigs, stems, and trunks; orange fruiting bodies may be present?

Polyphagous shot hole borer bores perfectly round, small entry-holes into trunks and primary branches. It then creates galleries in the wood where it lays its eggs and grows the Fusarium fungus. Most heavily infested or isolated host trees need to be removed entirely or pruned (if the infestation is confined to a few branches). Chemical treatment requires a bark spray for the beetles combined with soil injection of a fungicide.

Armillaria root rot is a fungal disease that cannot be effectively controlled once it has become established. Diseased or dead plants should be uprooted and removed. Planting resistant rootstocks is the most effective method of preventing the disease.

These symptoms indicate a fungal disease - Anthracnose. Keep plants dry when watering to prevent spread. Spray plants with copper when the first fruit develops if you have had problems in the past. Bordeaux mixture can also help to protect the plant from the disease.

These symptoms indicate fungal disease Phytophthora Root and Crown Rot. Phytophthora pathogens are favored by wet conditions, and the risk of disease can be reduced with good water management. The disease tends to affect plants in poorly drained areas, where susceptible plants are surrounded by standing water or saturated soil for prolonged periods. Provide adequate drainage and know the water needs of individual plants.

Nectria canker on trees is a fungal infection. The pathogen known as nectria invades fresh wounds and damaged areas of bark and wood. Orange fruiting bodies appear during spring and summer. Nectria rarely kills older, established trees. There is no cure for nectria canker. Prevent it by avoiding pruning during wet conditions, and by protecting your trees from winter injury.

If your oak is wilting and dying and the roots are dark-brown it is suffering from a fungal disease - Pythium Root Rot. Remove and dispose of the affected plant. Do not overwater plants. Apply a copper-based fungicide to protect plants.