What Is Wrong With My Japanese Zelkova?

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 which are gray to straw in color?

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

Do the stems have swollen, tumor-like growths on them?

Are there any browning of the leaves that started at the lower branches, and is affecting only a part of the tree?

Are there any 1/4 inch long, olive-green beetles with black, longitudinal stripes along the margin and center of the back?

Are the leaves yellow, branches, and leaves are covered with small bumps?

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.

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.

Bacterial disease Crown gall causes wartlike swellings on stems of a Japanese zelkova tree. Gall bacteria are introduced into plants that are vulnerable due to wounds. If the plant is only slightly infected, prune off diseased growth. Destroy severely infected plants and avoid replanting Mandevilla or any susceptible plant species in the same spot.

Dutch elm disease usually starts on lower branches, and may appear random, affecting only part of the tree and leaving another part unscathed. The disease is caused by a fungus spread by elm bark beetles. There is no cure for Dutch elm disease but the tree may respond if prune off all affected branches. This is a treatment that extends the life of the tree for several years if caught early and done properly.

The elm leaf beetle adults chew entirely through the leaf, often in a shothole pattern. Larvae skeletonize the leaf surface, causing damaged foliage to turn brown to whitish. Elm leaf beetles, when abundant, can entirely defoliate a large tree. Clear all debris around trees. Check for dead or dying branches and promptly remove them. Where foliage can be thoroughly sprayed, nonresidual, contact insecticides can provide control. Products include azadirachtin, neem oil, narrow-range oil, and pyrethrins.

Soft scales are known to attack Escallonia. Scrape off minor infestations with your fingernail. Prune out badly infested growth, or use a soft brush and soapy water to gently scrub the scales off the stems. Control scales by spraying insecticidal oil during the growing season.

Mineral deficiencies can cause tip chlorosis or necrosis or cause foliage to discolor, fade, distort, or become spotted, sometimes in a characteristic pattern that can be recognized to identify the cause. When nutrient deficiencies occur, nitrogen and iron are the most commonly seen deficiencies. Apply only the mineral found to be deficient. Excess nutrients, on the other hand, cause symptoms like leaf tip dieback, marginal leaf chlorosis, necrosis (or burn), branch dieback, and pest problems. In this case, you should provide good drainage, and use good practices during fertilization and irrigation.