University of Maryland Extension

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Surface Roots - Trees and Shrubs

Tree roots growing at or slightly above the soil surface are called surface roots. Surface roots can make it difficult to mow the lawn or grow grass. When trees and grass compete for moisture and nutrients, the tree roots usually win. Grass growing over or near surface roots may become thin and...

Spot Anthracnose of Dogwood or Elsinoë Leaf spot

The fungus Elsinoë corni causes a spot anthracnose primarily on Cornus florida . This disease should not be mistaken for another more serious dogwood disease called dogwood anthracnose caused by the fungus Discula destructiva . The disease can infect flower bracts, leaves green stems, and fruit...

Slime Flux and Wetwood - Trees and Shrubs

Wet, bleeding wound on a tree trunk The most obvious symptom is sap flowing from bark cracks or other wounds in the trunk or branches. This sap flow may be more abundant at certain times of the year or may stop entirely and then restart again. This condition will cause dark streaks on the bark...

Poor Plant Material - Trees and Shrubs

When a plant does not grow at the expected rate poor plant material may be responsible. Plants that are weak or damaged when planted may never overcome initial problems and will fail to thrive. Always choose top quality plant material. Inspect the roots, trunk, and structure of the plant before you...

Poor Plant Care - Trees and Shrubs

Poor planting technique There are several factors to consider when a plant does not grow at the expected rate: it may not be fully established, it may not have received proper care, or it may be poorly adapted to the site. A field-grown tree can lose up to 90% of its root system in the...

Plant Bugs - Trees and Shrubs

Damage to honey locust Plant bugs are small sucking insects (2-9mm) that feed on the leaves of many shade trees including ash, oak, hickory, birch, honeylocust, and sycamore. The plant bugs feed by piercing the leaves with their tube-shaped mouthparts, injecting an enzyme into the leaf tissue and...

Natural Gas Injury - Trees and Shrubs

Natural gas, composed mostly of methane, is not directly toxic to plants, however when a gas leak occurs it displaces the oxygen in the soil pore spaces. This can lead to development of anaerobic conditions and eventually the production of hydrogen sulfide gas. Hydrogen sulfide inhibits root...

Natural Decline - Trees and Shrubs

Branch dieback in crown of tree A tree that is in decline lacks vigor, has reduced growth and shows other stress symptoms. You may also notice small leaf size, wilt, leaf scorch, early fall color, early leaf drop, and/or dieback. Other symptoms include abnormally large crops of fruit or nuts and...

Leafhoppers - Trees and Shrubs

Leafhopper damage on maple Adults of most leafhoppers are one-eighth to one-fourth inch long, slender and hold the wings roof-like over the back. Many have angular, pointed heads. Immature leafhoppers, or nymphs are similar to the adults but smaller with short wings. Most pest leafhoppers are green...

Leafminers - Trees and Shrubs

Leafminer damage Leafminers feed on leaf tissue between the upper and lower surfaces of a leaf. They may be the immature stages of moths (caterpillars), beetles, flies or sawflies. Most cause little damage. Several are pests of shade trees. These include the holly leafminers , locust leafminer ,...

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