Michigan has many tree species that are subject to disease and pests. Half of Michigan is made up of forests and there are five common forest types with each forest growing one or more tree species. Even though Michigan has a huge harvest of threes each year to feed it lumber industry, the state still has more trees than can possibly be harvested without devastating the resources.
The white birch tree is found in the forest with the big-tooth aspen and the quaking aspen. The soils that the trees grow in are sandy to wet clay loamy soils to dry clay loamy soils. The aspen tree is prone to the aspen tortrix and the gypsy moth. The most serious disease to affect the tree is the Hypoxylon canker, which attacks mature trees. The aspen tortrix is a small caterpillar, dark in color, that feeds on the leaves and leaves egg masses on the foliage. Trees don't usually die from this disease, but it can stunt the growth of the tree.
Beech and Maple
The American beech and sugar maple trees grow in well-drained but moist soils of Michigan. The pest that invades the forest where the beech and maple grow is the forest tent caterpillar. The Nectria canker can cause a serious loss of trees in the hardwoods such as the maple and beech. The Nectria canker is a fungus that is creamy white in color and looks like a canker. The underlying wood and bark can be killed by the canker fungi. The canker appears as a hole or opening in the tree trunk that can become larger over the years.
The bur oak, white oak and the northern red oak trees grow in the forest with sandy soils with good drainage. Oak wilt disease, gypsy moth and the oak worm are pests and disease that can affect the oak trees. The oak wilt disease can kill a tree in one to three years. The disease is a fungal bacterium that can spread from tree to tree by insects or underground through the root system. Most trees affected by the disease have an injury on the trunk or branches that allows the fungi to enter. The gypsy moth feeds on the tree foliage and over the years of continued loss of foliage can kill the tree.
Ash and Elm
The green ash, black ash and elm trees grow in Michigan. The trees grow in floodplains where the soil drains poorly and remain wet for long periods of time. Dutch elm disease affects the elms and the heartwood decay disease and canker worms affect both species. Heartwood decay disease affects the heartwood, sapwood and roots of the tree. The disease is caused by fungi and begins when part of the tree is injured. The tree becomes weal and is prone to wind throw, which will knock the tree over in high winds. Elm disease is a bacterium like organism that will cause the tree leaves to wilt, turn yellow and fall off the branches.