Signs of Tree Disease

Since there are so many different symptoms of tree disease, it is best to use a

Tree Disease Problem Solver - like this one from Penn State University:

http://paipm.cas.psu.edu/ProblemSolvers/land1ProblSolv.htm

Additional Tree Disease Info:

The Top 5 Deadly Coniferous Tree Diseases

There are virulent diseases that attack coniferous trees which ultimately cause death or devalue a tree in the urban landscape and rural forest to the point where they need to be cut. Five of the most malignant diseases have been suggested by foresters and landowners at About's Forestry Forum. These diseases are ranked according to their ability to cause aesthetic and commercial damage. Here they are:

#1 - Armillaria Root Disease: The disease attacks both hardwoods and softwoods and can kill shrubs, vines, and forbs in every state in the United States. It is pervasive in North America, commercially destructive and is my pick for the worst disease.
The Armillaria sp. can kill trees that are already weakened by competition, other pests, or climatic factors. The fungi also infect healthy trees, either killing them outright or predisposing them to attacks by other fungi or insects.

#2 - Diplodia Blight of Pines: This disease attacks pines and is most damaging to plantings of both exotic and native pine species in 30 Eastern and Central States. The fungus is seldom found in natural pine stands.
Diplodia pinea kills current-year shoots, major branches, and ultimately entire trees. The effects of this disease are most severe in landscape, windbreak, and park plantings.
Symptoms are brown, stunted new shoots with short, brown needles.

#3 - White Pine Blister Rust: The disease attacks pines with 5 needles per fascicle. That includes Eastern and Western white pine, sugar pine and limber pine. Seedlings are in greatest danger.
Cronartium ribicolais a rust fungus and can only be infected by basidiospores produced on Ribes (current and gooseberry) plants. It is native to Asia but was introduced to North America. It has invaded most white pine areas and is still making progress into the Southwest and into southern California.

#4 - Annosus Root Rot: The disease is a rot of conifers in many temperate parts of the world. The decay, called annosus root rot, often kills conifers. It occurs over much of the Eastern U.S. and is very common in the South.
The fungus,Fomes annosus, usually enters by infecting freshly cut stump surfaces. That makes annosus root rot a problem in thinned pine plantations. The fungus produces conks that form at the root collar on roots of living or dead trees and on stumps or on slash.

#5 - Fusiform Rust of Southern Pines: This disease causes death within five years of a tree's life if a stem infection occurs. Mortality is heaviest on trees less than 10 years old. Millions of dollars are lost annually to timber growers because of the disease. The fungus Cronartium fusiforme requires an alternate host to complete its life cycle. Part of the cycle is spent in the living tissue of pine stems and branches, and the remainder in the green leaves of several species of oak.

The Top 5 Deadly Hardwood Tree Diseases

There are virulent diseases that attack hardwood trees which ultimately cause death or devalue a tree in the urban landscape and rural forest to the point where they need to be cut. Five of the most malignant diseases have been suggested by foresters and landowners at About's Forestry Forum. These diseases are ranked according to their ability to cause aesthetic and commercial damage.

#1 - Armillaria Root Disease: The disease attacks hardwoods and softwoods and kills shrubs, vines, and forbs in every state. It is pervasive in North America, commercially destructive, a major cause of oak decline and is my pick for the worst disease.
The Armillaria sp. can kill trees that are already weakened by competition, other pests, or climatic factors. The fungi also infect healthy trees, either killing them outright or predisposing them to attacks by other fungi or insects.

#2 - Oak Wilt: Oak wilt, Ceratocystis fagacearum, is a disease that affects oaks (especially red oaks, white oaks, and live oaks). It is one of the most serious tree diseases in the eastern United States, killing thousands of oaks each year in forests and landscapes.
The fungus takes advantage of wounded trees - the wounds promote infection. The fungus can move from tree to tree through roots or by insects. Once the tree is infected there is no known cure.

#3 - Anthracnose Diseases: Anthracnose diseases of hardwood trees are widespread throughout the Eastern United States. The most common symptom of this group of diseases is dead areas or blotches on the leaves. The diseases are particularly severe on American sycamore, the white oak group, black walnut and dogwood.
The greatest impact of anthracnose is in the urban environment. Reduction of property values result from the decline or death of shade trees.

#4 - Dutch Elm Disease: Dutch elm disease primarily affects American and European species of elm. DED is a major disease problem throughout the range of elm in the United States. The economic loss resulting from death of high value urban trees is considered by many to be "devastating".
Fungus infection results in clogging of vascular tissues, preventing water movement to the crown and causing visual symptoms as the tree wilts and dies. American elm is highly susceptible.

#5 - American Chestnut Blight: The chestnut blight fungus has virtually eliminated the American chestnut as a commercial species from eastern hardwood forests. You only now see the chestnut as a sprout as the fungus eventually kills every tree within the natural range.
There is no effective control for chestnut blight even after decades of massive research. The loss of American Chestnut to this blight is one of forestry's saddest stories.