Why is my Black Hills spruce turning yellow?
By Eleanor Gray
Why is my Black Hills spruce turning yellow?
Lirula needle blight causes the inner needles of spruce trees to turn yellow then gray. Caused by the fungus Lirula macrospora. White spruce, including Black Hills spruce, is more likely to be damaged. Fungicides can be used to protect new needles from infection.
What causes spruce trees to turn yellow?
The yellowing or off-color of older, interior spruce needles are most likely symptoms of trees having root system problems. Although excessively dry soils have also been implicated as a potential cause, most commonly, spruce trees growing in excessively wet soil conditions will be the reason for the symptoms.
Why are the spruce needles discolored?
If needles are browning at the tips of the branches followed by lower branches dying, you may be dealing with a fungal disease known as cytospora canker, which is the most common unnatural cause for needle drop on Colorado blue spruce. Another common spruce tree disease is rhizosphaera needle cast.
What is killing my Norway spruce?
Quick facts. Rhizosphaera needle cast is a fungal disease of spruce trees that causes needles to turn brown and fall off. Trees stressed from drought, poor planting practices or other factors are more likely to suffer from Rhizosphaera needle cast.
Why are the needles on my spruce tree turning brown?
Another problem has been noted recently on spruce in several states, including Wisconsin, Missouri, Kansas, and Minnesota. Needles on the older growth of individual branches quickly turn yellow or brown before falling off, usually leaving behind only the newest growth. Affected branches may be scattered through the canopy.
What kind of disease does Black Hills spruce have?
This January, the ISU Plant and Insect Diagnostic Clinic received samples from Black Hills spruce trees in Cerro Gordo County. The symptoms were typical of sudden needle drop, and were apparently causing eventual death of the trees.
How old are the needles on a spruce tree?
Damage typically starts on the lower branches and moves up the tree affecting susceptible spruce trees when 15 to 20 years old. Close inspection using a hand lens will reveal tiny black dots on infected needles—stomata (tiny holes that allow gas exchange) are white on healthy needles.
What to do about blue spruce needle blight?
Lirula needle blight can be prevented on blue spruce by spraying trees with a fungicide containing the active ingredient chlorothalonil or a Bordeaux mixture when new growth is approximately half of its expected growth for that year. Spray again one month later and repeat for the next two years.
Why are the needles on my blue spruce tree turning yellow?
A wide range of diseases, mostly fungal in origin, can cause yellow needles to develop on blue spruce trees. Treatment varies depending on disease, but in all cases, preventative measures, such as selecting blue spruces from a reputable grower and not planting in areas where yellow needles has been a problem in previous years, are helpful.
When do the needles fall off a spruce tree?
Older needles closer to the trunk of the tree become discolored and fall off mid-summer, leaving the tree looking thin and bare. Damage typically starts on the lower branches and moves up the tree affecting susceptible spruce trees when 15 to 20 years old.
This January, the ISU Plant and Insect Diagnostic Clinic received samples from Black Hills spruce trees in Cerro Gordo County. The symptoms were typical of sudden needle drop, and were apparently causing eventual death of the trees.
When to know if a white spruce is infested?
• Prefers balsam fir, but readily feeds on white spruce. • Larvae present in late May through June. • Larvae tie needles and shoots together with silk. • Infested trees appear scorched because clipped, dead needles get caught in silk. • Empty pupal cases often present year-round. • Several years of heavy defoliation can kill trees. Management
