Minnesota Tree Care Advisors

Characteristics
Disease Management

This Minnesota native has been planted extensively, some believe over-used, in urban settings due to its "tough" characteristics or tolerance to urban stresses.

Large tree height:		40-60'

Canopy spreads:		30-50', Rounded crown.

Drought Tolerance:		Tolerant

Shade Tolerance:		Intermediate

Soil pH Tolerance:		Tolerant to high pH

Poor Soil Drainage:		Tolerant to flooding

Salt Tolerance:		Intermediate to salt spray and Intermediate to soil salts.

Not always an attractive or handsome tree, this oppositely branched tree has smooth gray bark when young that matures to a rough bark with diamond or canoe shaped patterns to the ridges. Foliage is a compound leaf that is dark green in the summer becoming brilliant yellow in the fall. Flowers, dioecious, green to purple in color, but not that significant for aesthetics. Fruit is a winged samara that is eaten by wildlife. The leaf scars are somewhat of an ID characteristic and on green ash are a closed "C" - nearly straight across the top.

This species grows in many soil types and micro climates, couple that with its ease of transplant and one understands its popularity in nurseries. There are several varieties to be found in the nurseries: Patmore, Marshall's seedless, Bergerson, and Summit to name a few. After DED swept Minnesota in the early 1970's green ash was commonly planted as a street tree to fill the void. In the wild this species is found in moist bottomlands and is flood tolerant; yet, once established this is a species that handles drought and other soil issues very well.

Did you know
Of the American members of the ash family - green ash has the distinction of being the member that has traveled the farthest and maintains the widest distribution.

DISEASE		SYMPTOMS	MANAGEMENT
Anthracnose, Apiognomonia errabunda	Fungi	Initially, tiny purple/brown spots on young leaves. Spots enlarge, coalesce and form brown blotches. Leaf distortion common. Young shoots may be killed back. Defoliation may be severe.	Remove fallen leaves and dead twigs and branches, especially on young trees. CHEMICAL: Chlorothalonil, mancozeb, thiophanate-methyl or zyban beginning at budbreak.
Ash yellows, caused by a phytoplasma (mycoplasma-like organism)	Phytoplasma (MLOs)	Severe reduction in growth, chlorotic leaves in tufts at end of branches along with dieback. Witchesâ brooms may form on the trunk.	Maintain tree vigor to prolong life. Remove as they become hazard trees. CHEMICAL: None. REFERENCE: Ash Yellows in Minnesota, MI-5898-C.
Heart rot, Perennoporia fraxinophila	Fungi	Crumbly, soft decay in trunks and larger limbs. Groups of bract-shaped, grayish-white perennial conks appear along the infected branches and trunk.	Remove dead and dying branches. Avoid mechanical injury. CHEMICAL: None.
Sulfur shelf heart rot, Laetiporus sulfureus	Fungi	Brown cubical rot of roots, butt and trunk with sunken elongate cankers on the surface. Bright yellow to orange, fleshy fungal reproductive structures appear in summer and fall.	Proper pruning: avoid mechanical injury. CHEMICAL: None.
Verticillium wilt, Verticillium dahliae	Fungi	Acute or chronic symptoms may appear anytime during the growing season. Chronic: small, chlorotic leaves, leaf scorch, slow growth, abnormally heavy seed crop, shoot dieback. Acute: leaf curling or scorching, abnormal red or yellow color, partial defoliation, wilting, and branch dieback, plant death. Symptoms often on only one part of the tree or shrub.	This wilt is soilborne; replace with resistant tree species. Keep infected trees well watered and fertilize with a fertilizer high in potassium. Remove dead branches. CHEMICAL : None. REFERENCE: Verticillium Wilt of Trees and Shrubs AG-FO-1164