Last year we received many calls from homeowners worried about their spruces: needles browning, dropping, crowns thinning and general decline. In most cases the problems are fungal and caused by cool, wet weather. It is very important that you have a CERTIFIED ARBORIST check out a problem tree. Here are some of the problems we are seeing:
RHIZOSPHAERA NEEDLE CAST:
Infection takes place in April and May. The second year and older needles turn rusty red/purple then drop, generally in the lower branches, causing severe needle drop. Spores are spread by wind, rain, birds, insects, and humans. This can be controllable with fungicide sprays in the spring and good sanitation practices. Colorado blue spruce are the most susceptible. Norway spruce have a bit more resistance, but can also become infected.
STIGMINA NEEDLE CAST:
Same symptoms and infection time as Rhizosphaera. The only way to distinguish is through lab testing. Stigmina affects all spruces. There is currently no method of control other than prevention through cultural practices to lessen the spread.
SUDDEN NEEDLE DROP DISEASE:
Also known as SNEED. Causes yellowing and browning of older needles. Affected branches are scattered throughout the crown. By fall all the needles on the infected branches have dropped off except the needles on the tips of the branches.
PHOMOPSIS SPRUCE DECLINE:
This is newly discovered fungus in St. Louis area, but has been a major problem for the Christmas tree industry in the northeast. It mainly affects Englemann Spruces, and Colorado blue spruces but is also being found in Norway spruces. Symptoms include dead branches, browning and dropping needles that usually show up on the bottom and work their way up the crown. The fungus also causes small cankers just under the bark killing off new shoot growth.
If you have spruces, good sanitation practices are critical. Before Spring (March or early April) clean up and discard any old needles, cones or twigs laying under or around the spruces. Prune out as much of the limbs where the needles have fallen as they may contain the fruiting bodies of the fungus. Make sure there is a minimum of 3-5” between the lowest limbs of the spruce and the ground to facilitate better air ow and quicker drying times after a rain or irrigation period.
Also a deadly disease to spruces, especially Blue Spruce and Norway Spruce. This fungus will cause needle loss and dieback in the lower branches. The spores are also spread by wind, rain, birds and insects. There is nothing that can be done to prevent cytospora, and no treatment if your tree becomes infected.
When making changes to your landscape, please be aware that spruces will require constant maintenance and care. If you are considering spruces for screening, there are alternatives.
More on Spruce Decline
More on Cytospora Canker