Disease	Symptoms	Pathogen/Cause	Management
Black Leaf Spot	Small, black, slightly raised, rough spots form on leaves. Leaves yellow and fall prematurely.	Stegophora ulmea (formerly Gnomonia ulmea)	No control is recommended for trees in the landscape.
Botryodiplodia Canker	Cankers form on twigs and branches. The junction of cankered and healthy wood is sharply defined under the bark where reddish-brown infected wood meets white healthy wood. Leaves on infected branches turn bright yellow and fall without wilting (See Dutch Elm Disease and Phloem Necrosis below). In the autumn, fungal fruiting structures roughen the bark of infected twigs.	Botryodiplodia	Irrigate to prevent drought stress. Prune infected branches well below the canker. Disinfest pruning tools frequently.
Dutch Elm Disease	Leaves on one or more branches wilt, yellow, and fall prematurely. Progressively more branches exhibit symptoms. Outer layers of sapwood of affected branches have brown streaks.	Ophiostoma ulmi (formerly Ceratocystis ulmi)	Resistant cultivars are available including Accolade, Sapporo Autumn Gold, Regal, New Horizon, New Harmony, Valley Forge, Independence, Cathedral, Urban, Princeton, Pioneer, Prospector, Frontier, Homestead, Patriot, Ohio, Pathfinder, Jefferson, and Dynasty.
Management of Dutch Elm Disease Remove severely infected trees promptly. Peel the bark off the stump to below the soil line. Burn or bury all wood greater than 1/2 inch in diameter promptly. Do not stockpile it for later burning unless it is first tarped and fumigated promptly to kill bark beetles. Midway between elms within 50 feet of the infected elm, trench 2 feet deep to cut root grafts. Or, dig holes 2 inches in diameter, 2 feet deep, and 6-8 inches apart in a line between the infected elm and elms within 50 feet. Mix 1 part Vapam* and 4 parts water and pour 1 cup into each hole. Plug the holes with a chunk of sod. This fumigant will kill root grafts. If less than 5% of the crown of a tree exhibits symptoms, find the lowest point of vascular streaking and prune the branch at least 12 feet below that point. Inject Arbotect* or Alamo* (Banner*). Maintain good elm bark beetle control. Treating unwanted elms with cacodylic acid has been found to make the dying tree attractive to elm bark beetles, which carry the fungus but brood production in those trees is greatly suppressed.
Ganoderma Rot	Very distinctive shelf-like fruiting structures form annually on the wood singly or in overlapping clusters. They are brown to reddish brown on top with a cream- to white-colored margin, and may become 14 inches across. The upper surface may appear to have been varnished. Branches and eventually the entire tree dies as the rotting progresses.	Ganoderma lucidum	A tree with fungal fruiting structures on the trunk, butt, or roots should be removed promptly if it is in a location where property damage may occur or where people or pets could be struck by falling limbs or the falling tree.
Inonotus Root Rot	Root and butt rot may cause trees to topple before any obvious symptoms are noted. Infected trees often have a branch dieback and fewer than normal leaves that are yellowed. Although the root rot begins well out on the root system, the fungus eventually reaches the butt of the tree where it forms large, tough, irregularly shaped light- to dark-brown shelves at or just above the soil line. With age, these become very rough and dark brown to black. Cutting the shelf reveals a reddish-brown center. The underside of the shelf is brown with millions of tiny pores in which the spores are formed.	Inonotus dryadeus (formerly Polyporus dryadeus)	A sure sign of severe damage to the tree is the presence of the fruiting structures. Infected trees should be removed immediately.
Laetiporus Root Rot	Massive clusters of bright, sulfur-yellow to salmon to bright-orange shelf-like fruiting sturctures that turn white with age initially form in the summer or autumn on the wood of the tree but fall off during the winter. The underside of the fruiting structure has millions of tiny pores in which the spores are formed. New shelves form on the wood the following summer and autumn. The bark where the fruiting structure forms is slightly depressed and cracked.	Laetiporus sulfureus (formerly Polyporus sulfureus)	Fruiting structures form long after most of the damage has been done. Infected trees are very prone to wind breakage even before the fungus begins to form fruiting structures. The tree should be removed at the first sign of infection.
Leaf Scorch	Early to midsummer, leaves on a few branches have a marginal leaf burn of scorch. Symptoms increase on the leaves later in the summer. The line marking the boundry between dead and living leaf tissue is wavy and has a definite yellow halo. Leaves usually fall prematurely. More branches become involved in following years.	Xylella fastidiosa	Leafhoppers and spittle bugs carry the baceria from tree to tree. Infected trees may survive years. Severely affected trees should be removed since they are attractive to elm bark beetles which can carrying the Dutch elm disease fungus.
Phloem Necrosis (Elm Yellows)	Leaves yellow and wilt over the entire crown of the tree and fall prematurely in summer. Trees may die within 1 year. Roots are killed early in disease development. The inner bark (phloem) and the outer most layer of xylem (water conducting tissue) is yellow or butterscotch in color and has a definite oil of wintergreen odor if held to the nose immediately after cutting. If a piece of the discolored bark is placed in a tightly sealed jar, the wintergreen smell will accumulate.	Phytoplasm	White-banded American leafhoppers feeding on the phloem of elms move the mycoplasmas from tree to tree. No effective control is available. remove the infected tree.
Wetwood (Slime flux)	Foul-smelling liquid oozing from branch stubs, pruning cuts, or cracks in the bark runs down the trunk, leaving gray streaks. Bark and turf where the ooze lands may be killed. Affected wood within the tree has a water-soaked appearance but rarely has decay.	Many bacteria are involved.	Wetwood does no apparent damage to the tree unless the tree comes under some other severe stress. Protect the tree from stresses such as soil compaction, excavation, or drought. Do not insert pipes to relieve pressure. Avoid wounding the tree in any way.

*Trade name