Minnesota Tree Care Advisors

Characteristics
Disease Management

Bigtooth aspen is a native to Minnesota and is often simply referred to as poplar. Typically, the lay person makes no effort to distinguish the trembling aspen and bigtooth aspen. It often is simlpy that there is no awareness of a distinction to be made.

Medium tree height:		40-50'

Canopy spreads:		20-40', Often a narrow, pyramidal crown when young and developing an oval open crown at maturity.

Drought Tolerance:		Intermediate

Shade Tolerance:		Intolerant

Soil pH Tolerance:		Tolerant to high pH

Poor Soil Drainage:		Intermediate to flooding

Salt Tolerance:		Sensitive in tolerance to salt spray and Intermediate in tolerance to soil salts.

Bigtooth aspen and Trembling aspen are very similar in many characteristics (Form, sound of rustling leaves and wood quality). The leaves are distinct with the bigtooth aspen having larger teeth (termed dentate) on the leaves and the shape of the bigtooth aspen leaf is not as ovoid as that of trembling or quaking aspen.

Another subtle difference can be found by looking at the lateral buds along the twigs. Lateral buds on bigtooth aspen tend to be divergent of the twig or it is said that they point away from the twig while the buds of trembling aspen almost wrap the twig (incurved) or hook around the twig. The twigs tend to be stouter than those of trembling aspen.

In other regards the tree is similar to its close cousin, trembling aspen. Both are used for pulp wood and OSB (Oriented Strand Board). Both have yellow fall foliage while the summer foliage is green. The rustling sound produced by poplars - is generated in part by the flattened petiole.

Not an important landscape tree due to insect and disease problems, but never the less it is used occasionally.

Did you know
Important tree in the wild - it is a pioneer species - readily seeds in on freshly disturbed sites and readily root sprouts after a timber harvest.

DISEASE		SYMPTOMS	MANAGEMENT
Cankers, Valsa sordida (Cytospora chrysosperma), Phompsis sp., Hypoxylon sp., Mycosphaerella populorum, Cryptodiaporthe populea	Fungi	Fungi infect young twigs or wounds creating cankers on branches and trunks. Fruiting bodies commonly form on the face of cankers. Widespread and common on poplar, cottonwood, aspen and willow. Especially serious on Lombardy and silver leaf poplars.	Maintain plant vigor. Remove cankered branches during dry weather. Avoid wounds. Avoid planting in areas with poor air circulation. Trees prone to many cankers should be replaced with another tree species. CHEMICAL: None.
Leaf rust, Melampsora medusae and other species	Fungi	Yellow to orange pustules break through the surface on both leaf surfaces in mid to late summer. Angular yellow lesions may occur on the opposite leaf surface. Lesions turn black in autumn. Some defoliation may occur. Alternate hosts include hemlock, Douglas-fir, larch, and pine depending on rust species.	Choose a poplar clone with resistance. Keep susceptible conifers 500 yards away from poplar stock. CHEMICAL: Seldom necessary in landscape settings. Triadimefon or triforine.
Marssonina leaf spot, Marssonina populi	Fungi	Small brown leaf spots with yellow margins. Infection may advance into stem tissue. May be severe during wet seasons resulting in defoliation.	Collect and destroy leaves. Plant in areas with good air circulation. CHEMICAL: Fungicides seldom warranted in landscape plantings. NURSERY: Chlorothalonil at bud break and every 7-10 days if necessary.
Shoot blight, Venturia tremulae on Populus sp. and hybrids; V. populina on black cottonwood and balsam poplar	Fungi	Brown to black leaf spots rapidly expand on succulent tissue to cause shoot blight. Affected tissues dry out and become brittle.	Remove and destroy infected shoots. Increase air circulation. Rake and remove leaves in the fall. CHEMICAL: Seldom necessary in landscape settings.