Trees to Avoid
(Trees Which Are Often Used, But Have Serious Insect, Disease, Or Litter Problems)
Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist
SYCAMORE (Platanus occidentalis) 75-100'. A very large tree which should not be planted except on the largest lots. Constantly dropping leaves, twigs, and seed clusters. Sycamore blight (anthracnose) is a serious disease problem. It appears to be very sensitive to injury from the herbicides 2,4-D and dicamba, even when used properly.
TREE OF HEAVEN (Ailanthus altissima) 40-60". This tree is adaptable to the most difficult of conditions but it is a course tree that tends to be very weedy. Should be planted only in impossible situations where nothing else survives.
SILVER MAPLE (Acer saccharinum) 50-120'. Another very large tree with a fast rate of growth. It tends to be a very weak wooded subject to many disease and insect problems. There are many superior forms of maple with many more desirable aspects. Has very little fall color. Roots are very invasive.
BOX ELDER (Acer negundo) 30-50'. This is another fast growing, weak wooded maple. It tends to be susceptible to many disease and insect problems. Very susceptible to verticillium wilt. The white variegated form has some merit. Short-lived tree.
POPLAR (Populus alba) 40-90'. This is an easy to grow "trashy" tree that continually drops leaves, twigs, and other debris. It is weak-wooded and tends to be weedy. Susceptible to many diseases and wood borers. Short-lived tree. Water seeker, invasive roots.
COTTONWOOD (Populus deltoides) 75-100'. Very large tree with all the problems of the preceding poplar. Water seeker, invasive roots.
PIN OAK (Quercus palustris) 60-70'. This is a good tree although there are many better oaks available, but it is intolerant of the alkaline soils encountered in this area.
WEEPING WILLOW (Salix sp.) 50-80'. A well loved tree but out of place in the normal home landscape. It is extremely weak wooded and very susceptible to aphids. The root system is very invasive.
RUSSIAN OLIVE (Elaeagnus angustifolia) 15-40'. Not the most beautiful of trees, but has a purpose in saline soils or where gray foliage is desired. It tends to be a rangy, weedy plant. Very susceptible to verticillium wilt, crown gall and aphids.
SIBERIAN ELM (Ulmus pumila) 50-70'. Does not deserve to be planted in the landscape. A shrubby tree with poor form. Brittle wood. Very susceptible to insects - especially aphids and the elm leaf beetle.
CRAB APPLE (Malus sp.) Crabapples are very nice trees but their fruit, large or small, are attacked by codling moth and apple maggot. Because these pests cause problems for local commercial apple growers, it’s not recommended to grow them in this region unless you intend to spray regularly with recommended pesticides to control these pests. In fact, it’s county law that you control these pests or remove your tree.
LAVELLE HAWTHORNE (Crataegus lavellei) 20-30'. A nice tree with lustrous deep green foliage and white showy flowers, but also should not be grown because it’s fruit are attacked by codling moth and apple maggot.