Table 1.

A selected representative list of dieback-decline diseases chosen to represent a variety of hosts, predisposing stresses, organisms of secondary action and control.

HOSTS AND DISEASE	TRIGGERING STRESS	ORGANISMS OF SECONDARY ACTION	EFFECTS (SYMPTOMS AND SIGNS)	CONTROL
AshAsh dieback, decline (general)^¹Fraxinus americanaF. pennsylvanica	Drought periods	Bark canker fungi: Cytophoma pruinosa Fusicoccum sp.	Reduced terminal and radial growth Death of terminal buds and branches Thin, “tufted” crowns Sometimes, early fall coloration Death of trees Reddish-brown to orangeyellow cankers on branches and stems	Forest: little can be done, salvage Urban: water when feasible, possibly reduce water loss by mulching
Dieback (general, near coastal salt marshes with Spartina grass hostsFraxinus spp.	Defoliation by rust fungus, Puccinia peridermiospora	None	Dieback occurs the season following severe defoliation/refoliation Death of terminal buds and branches Thin, “tufted” crowns Death of some trees	Most trees will recover unless defoliation is repeated or coincides with drought.
Beech Beech bark disease (general in east through NY and mid-PA; northeastern WV.) Fagus grandifolia F. syivatica	Attack by the beech scale, Cryptococcus fagisuga	Bark canker fungi: Nectria coccinea var. faginata; N. galligena	Thinning chlorotic crowns Presence on bark, especially in roughened spots, of white “wool-like” wax of the beech scale Presence on bark previously infested by scale of small, red fruiting bodies of Nectria fungi Weeping exudates may precede or accompany the fruiting bodies Bark is killed, and trees die. Some trees snap off where bark dies and wood decays	Forest: salvage trees when scale populations become high and Nectria is abundant. Trees free from scale (resistant) should be favored Urban: treat individual trees with dormant sprays or chemical fungicides registered for use against the beech scale
Dogwood Lower branch dieback, anthracnose (southern New England, northern midAtlantic states; urban, woodlands)Cornus florida, native and cultivars	Suspected: series of unusually wet springs, followed by summer dry periods	Leaf and twig fungus (Discula sp. Gnomonia sp.) of anthracnose type	Blighted leaves in early spring Dieback of buds, twigs and branches beginning on lowermost parts of tree Development of branch cankers Water sprouts from near branch cankers — these in turn are killed, trees die	Not yet known
Maple Maple decline (general;forest) Acer saccharum	Defoliation by a number of insects including: saddled prominent forest tent caterpillar maple webworm green stripped mapleworm	The shoestring root rot fungus, Armillaria mellea, and twig fungus, Stegonosporum sp.	Death of buds, terminal twigs and branches the year after severe defoliation Thin “tufted” crowns New foliage on sprouts Continued decline and death of some trees White fungus “fans” often present beneath bark of roots and bases of dead and dying trees	Forest: prevent defoliation, salvage if significant portion of crown is killed Urban: prevent defoliation
“Roadside” maple decline^² A. saccharum	Deicing salts, and/or construction damage to roots	Many twig, root and stem decay fungi	Crown dieback, especially on road side of tree Leaves show fall colors early and drop Leaves may also show inter- veinal necrosis (scorch) Dieback progresses over years, trees eventually die	Avoid use of deicing salt when feasible Plant replacement trees where brine will not run over roots
“Urban” maple decline (Wisconsin) saccharum	Suspect stress of planting trees too deeply in heavy soils, or settling of trees after planting	Soil borne canker fungi: Fusarium sp.; Phytophtho. citricola	Leaves small, show fall colors early and drop Twigs and branches die back c) Rootlets die Bark at tree base loosens to show discoloration and decay of underlying wood Trees die one to several years after first symptoms	Improve soil drainage Insure planting is shallow
Oak Oak decline (general) Quercus spp.	Defoliation by any of several insects including: gypsy moth leaf rollers and tiers canker worms webworms, etc., and sometimes exacerbated by periods of water shortage	The shoestring root rot fungus, A. mellea; and the twolined chestnut borer, Agrilus bilineatus	Dieback of terminal buds and branches in next season New foliage produced on sprouts in the crown and on the bole — crowns “tufted” Progressive dieback; mortality White fungus “fans” beneath bark (see Maple decline forest) “D”-shaped holes in bark and meandering insect galleries on outer sapwood beneath barka)	Forest: prevent defoliation: salvage Urban: as above; supply water during refoliation if feasible. Possibly spray tree trunks to prevent attack by borers
Oak decline (midwest; urban) Q. rubra Q. alba Q. macrocarpa	Adverse soil changes, including alkalinization, caused by various urban practices and disturbance	The shoestring fungus, A. mellea, and the borer, A. bilineatus	Deterioration of fine feeder root system Dieback and decline of upper crowns progressing sometimes until the tree dies Signs of A. mellea and A. bilineatus	Keep “wooded” areas as natural as possible; avoid watering with hard water, runoff from concrete surfaces, fertilizing with limebased fertilizers, mixing of soil by construction, grading, etc. Mulch and reduce grass competition
Oak decline (midwest; general) Q. rubra Q. Q. alba	Periods of unusual springtime wetness in areas where soil overlies dense clays	The shoestring fungus, A. mellea, and the borer, A. bilineatus	Rapid dieback and decline of mature and overmature trees Signs of A. mellea and A.bilineatus	None known
Pin oak canker dieback^³ (mid-Atlantic states; urban) Q. palustris	Pruning wounds made during drought	Bark canker fungus: Endothia gyrosa	Dieback of lower branches, especially those from which smaller ones have been pruned Death of some trees Orange-red to brown-black fruiting pustules on dead bark	Forest: not a problem Urban: water during drought periods. Avoid pruning during dry times.

↵1. Ash trees are hosts also to several viruses and a mycoplasmalike organism (MLO). Evidence is mounting that the MLO can cause growth loss and mortality — and effects may be especially serious in times of drought. This disease is now known as ash yellows, or ash yellow decline.
↵2. Both Na and Cl ions are cumulatively toxic to sugar maple. Heavy, repeated salt contamination can kill trees even in the absence of secondary organisms
↵3. Endothia gyrosa also causes cankers and dieback associated with pruning wounds in American and Formosan sweetgum and in American beech. In this respect it is similar to the fungus Nectria cinnabarina, a pruning wound pathogen of many urban tree species that is especially serious during severe droughts.