The tallest evergreen trees and the shortest shrubs face the same serious problems that may cause damage or death. Be observant and know what to look for in order to head off common evergreen problem in the early stages. The regulations regarding treatments differ from state to state, and even from community to community. Find out what treatments are available in your area at local extension services or reputable local garden centers.
Rhizosphaera needlecast is caused by the Rhizosphaera kalkhoffii fungus and attacks spruce trees, most predominately the Colorado blue spruce. In most circumstances, the disease is not fatal. Under normal conditions, a spruce tree will retain its needles for five to seven years. An infected tree will only keep the needles from the present year, leaving much of the branches bare. The lower branches fall victim first, with the disease slowly progressing up to the top. In the worst case scenario, the lower branches will die. The infection strikes in May and June. The first signs do not appear until fall or the following spring when wet weather releases fungal spores in infected needles that turn purple and drop off. Use a magnifying glass to spot the fuzzy black spots growing in the needle's spores.
Juniper Tip Blight
Juniper tip blight is caused by Phomopsis juniperovora, Kabatina juniperi or Sclerophoma pythiophila fungi. The disease attacks mostly young juniper trees and shrubs, causing twigs and branches to die back. Trees more than five years old can become infected, but the damage is not as serious. P. juniperovora also attacks arborvitae, white cedar, cypress and false cypress. S. pythiophila also attacks Douglas fir and eastern larch. Tips on the new growth die back first and the disease progresses back to the main stem. P. juniperovora and K. juniperi infections can be fatal, however S. pythiophila infection usually is not. Use a magnifying glass to look for small, brown fruiting bodies on the dead stems and leaves in the spring.
Diplodia Tip Blight
Diplodia tip blight causes the needles at the tips of pine branches to turn brown and die. All pine trees can become infected, but Austrian pine suffers the most sever damage. Repeated infections can kill a large Austrian pine. The first sign of the disease is the appearance of brown needles on the new growth of the lowest branches. The infection often spreads until the entire new growth is killed.
Use a magnifying glass to look for black fruiting bodies at the base of the diseased needles. Buds and twigs can also become infected.