University of Maryland Extension

Home and Garden Information Center

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Witches' Broom - Trees and Shrubs

An example of a witches' broom Witches' brooms are characterized by a proliferation of shoots growing close together. The shoots are usually shorter, stockier, and have an upright but more compact growth habit than normal. Witches' brooms may be caused by fungal, viral, or mycoplasma-like organisms...

Frost Cracks, Sunscald, Growth Cracks

Even hardy trees may develop sunscald or frost cracks . Tree bark warmed by the sun in winter can reach a temperature as much as 18 degrees warmer than the air temperature. When clouds shade the bark or temperatures drop quickly at nightfall, the bark and cambium layer beneath is damaged. This type...

Failure to Flower

Lack of blooms dogwood Excessive pruning of an azalea There are several possibilities as to why trees and shrubs may not produce flowers . Factors include maturity, environmental stresses, excessive lush growth, improper pruning, lack of pollinators, winter-kill and pesticides. Most flowering trees...

Eyespot Galls - Trees

Back to Shade Tree Galls The most colorful and noticeable of the eyespot galls (see above photo) occur on red maple. (They may also attack silver, striped and sugar maples). The spots are 8-10 mm in diameter. Eyespot galls are caused by a gall midge that rarely causes injury. The adult is a small...

Excessive Mulch

Mulches in general, are beneficial to plant growth, however, if the wrong kind or too much is used they may be detrimental to plants. Keep organic and synthetic mulches several inches away from the trunk to prevent excessive moisture and the possibility of crown rot diseases. Organic mulches should...

Eriophyid Mites

Closeup of eriophyid mites Adult eriophyid mites are very small (<1mm). They are spindle-shaped, with four legs and may be white, yellow or orange. You will need a hand lens to see them. There are several generations a year and overwinter in bark crevices and under bud scales. Some species feed...

Embedded Wires

Tree trunks may be deformed or girdled when hose and wires, ropes, or wire basket collars are not removed. The most common staking method consists of two wooden stakes supporting the tree with hose and wire around the trunk. The stakes, hose, and wire should be removed after the first year. Hose...

Elm Leaf Beetle

The elm leaf beetle, Pyrrhalta luteola will feed on all species of native and introduced elm and zelkova. All stages of the elm leaf beetle develop on or near the elm tree. Adult beetles are about 1/4 inch long and range in color from yellow to olive green with a black stripe along each side of the...

Early Fall Coloration

Early fall color can be caused by a number of factors including environmental stress, insect damage, and disease. Environmental stresses can be caused by severe drought, poor soil aeration, reduced root growth, nutrient deficiencies, extreme temperature fluctuations, defoliation, winter damage,...

Damage to Flowers

Photo: Freeze damaged Magnolia blossoms Factors that can cause blasted, damaged, or dropped blossoms include environmental stresses and pesticides. Environmental stresses that may damage flowers are drought, frost or freeze damage of flower buds or blossoms. Late winter sun can prematurely...

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