All Fact Sheets
Armillaria root rot, sometimes called shoestring root rot, is caused by various species of the fungus Armillaria. Susceptible plants include most deciduous and coniferous species.
Leaf scorch, sometimes called marginal leaf burn, describes the death of tissue along the edge of the leaf. This symptom develops when sufficient water does not reach the leaf margin cells.
Many mature trees, including elms, oak, tulip poplar, and maple, exhibit large light or dark vertical streaks on their trunks resulting from slimy liquid oozing out of crack or wounds and running down the bark. This is called 'slime flux'.
The fungus Plowrightia morbosa (Apiosporina) causes the formation of dark brown to black, long, swollen galls or knots on the branches of most types of cultivated plums, prunes and cherries.
The fungus Botryosphaeria can cause a branch dieback on horsechestnut, redbud, dogwood, beech, walnut, tulip poplar, sweetgum, crabapple, pine, oak, rhododendron, azalea, rose, willow, elm, yew, and many other woody ornamentals.
Localized areas of dead bark and underlying wood on twigs, branches and trunks are called cankers.
London plane and sycamore trees are susceptible to a fungus, Ceratocystis fimbriata f. sp. platani, that is lethal. The living cells of the wood in the phloem, cambium and sapwood are invaded quickly soon after a fresh wound exposes those cells.
Cedar-apple rust and closely related diseases, cedar-quince, cedar-hawthorn, and Japanese apple rusts are caused by fungi belonging to the genus Gymnosporangium.
Crown gall is caused by bacteria belonging to the genus and species Agrobacterium tumefaciens. This bacterium can infect a wide range of herbaceous and woody plants.
Blue and Norway spruces are susceptible to a branch killing disease caused by the fungus Cytospora kunzei.
Fire blight is a disease caused by the bacterium Erwinia amylovora. This bacterium can attack more than 75 species of trees and shrubs including apple, pear, quince, mountain ash, crabapple, hawthorn, cotoneaster, serviceberry, and pyracantha.
Most deciduous trees and many shrubs are susceptible to a disease called Verticillium wilt caused by the fungus Verticillium. Conifers do not appear to be susceptible.
Note the black fruiting structures on the curved part of this tip.