Common Aspen trees in our area:
Quaking Aspen:
- Broadleaf deciduous tree, 40-50 ft (12-15 m), pyramidal and narrow when young, long trunk and narrow, rounded crown when mature. Bark is thin, smooth greenish white to cream colored, furrowed dark brown or gray in old age. Leaves alternate, simple, thin, ovate to orbicular, 1.5-3 in long, finely glandular serrate, lustrous dark green above, glabrous below. Fine yellow color in fall. Laterally flattened petioles allow leaves to flutter in the slightest breeze (to "quake").
- Grows in many types of soil, from loamy sand to clay. Fast growing and relatively short lived. The most widely distributed tree in North America.
- In their habitat, quaking aspen forms clones connected by a common parent root system. Since trees are typically dieocious, a given clone may be either male or female. However, some clones produce both male and female flowers. In the West, quaking aspen stands are often even-aged, originating after a single top-killing event.
Common problems with Aspen trees:
Insects:
| Aphids | Galls | Cottonwood Leaf Beetle | Oystershell Scale |
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Aphids feed by sucking up plant juices through a food channel in their beaks. At the same time, they inject saliva into the host. Light infestations are usually not harmful to plants, but higher infestations may result in leaf curl, wilting, stunting of shoot growth, and delay in production of flowers and fruit, as well as a general decline in plant vigor. Some aphids are also important vectors of plant diseases, transmitting pathogens in the feeding process. A sticky glaze of honeydew may collect on lower leaves, outdoor furniture, cars, and other objects below aphid feeding sites. Honeydew coated objects soon become covered by one or more brown fungi known as sooty molds. Crusts of sooty mold are unsightly on man-made objects, and they can interfere with photosynthesis in leaves. |
This gall is produced by the feeding of an insect, the
poplar twiggall fly (Hexomyza schineri). The
galls (Figure 1) are smooth swellings on the current
season's twigs. What attracts attention and concern is that galled tissues continue to grow and swell. During subsequent years, the galled area is incorporated into the growing twigs and branches and may ultimately appear as large swollen bands on trunks and branches. Although these old injuries produce a permanent disfigurement, they do not seem to threaten tree health. MORE INFO |
Adults emerge in early spring,
feeding on bark and new leaves. Females lay yellow, oval
eggs in clusters under leaves. There are 2-4 generations
a year. |
Scale insects feed on plant sap. They have long,
threadlike mouthparts (stylets) six to eight times
longer than the insect itself. Feeding by scales slowly
reduces plant vigor. Heavily infested plants grow poorly
and may suffer dieback of twigs and branches.
Occasionally, an infested host will be so weakened that
it dies. |
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Insects (cont.): Diseases:
| Leafminers | Cankers | Leaf Spots | |
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Leafminers are usually the larvae of
flies, moths, or beetles that feed or “mine” between the
upper and lower epidermal leaf surfaces. The larvae
tunnel through the leaf creating a narrow, whitish
colored serpentine (winding) mine or blotch (blister) type mine. The tunnel is clear, except for the
trail of black fecal material left behind as larvae
feed. Female flies puncture or "stipple" leaves with
their ovipositors to lay eggs in the leaf tissue or to
feed on sap. Many ornamental plants are attacked by leafminers, but azalea, bougainvillaea, ixora, hollies,
chrysanthemum, lantana, oak, and boxwood are some of the
preferred hosts. |
The symptoms of this disease are yellow or orange-brown to black discolored areas on the bark of the trunk and branches. Liquid ooze on aspen and gummy ooze on peach and cherry are common. Cankers, sunken dead areas of bark with black pinhead-sized speckling or pimples, may be evident. The pimples are the reproductive structures of the fungus. Under moist conditions, masses of spores (seeds) may ooze out of the pimples in long, orange, coiled, thread-like spore tendrils. Reddish brown discoloration of the wood and inner bark also may be evident. Dead bark may remain attached to the tree for several years, then fall off in large pieces.
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The fungus Marssonina causes the most common foliage disease on aspen and cottonwoods in urban and forested areas. Marssonina leaf spots are dark brown flecks, often with yellow halos. Immature spots characteristically have a white center. On severely infected leaves, in wet weather, several spots may fuse to form large black dead patches. Spots also may develop on leaf petioles and succulent new shoots.
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