Colorado Blue Spruce Fungal Disease
Hello, Older needles on spruce naturally will die and fall. If you feel you are having more than the usual dieback of needles, read on. Colorado blue spruce are not native to Michigan and so suffer from a large variety of diseases, pests, and climatic challenges. I am including a list of these issues assembled by a colleague of mine, Barb Houchins. An accurate diagnosis is important, since some diseases cannot be effectively treated and some can. If these trees are of high value to your landscape I would suggest you get an accurate diagnosis, first. Below you will find links to finding a certified arborist in your area; or using the MSU Diagnostic lab, to determine what pests/diseases your trees have. I am also including the latest article discussing effects of our past winter. Please note that articles that are from other states may contain information specific to that state. The timing of treatments in Michigan may be different. Diagnosis: Find a certified arborist in your area. A certified arborist can your trees and make other recommendations for plant heath care. To locate one in your area visit the following website – and click on ‘Find an Arborist’ then plug in your zip code. http://www.treesaregood.com You may also send a sample to MSU Diagnostic Lab. Call 517-355-4536 for fees and sample instructions or visit their website at: http://pestid.msu.edu Winter of 2014 affected many trees: http://msue.anr.msu.edu/news/damage_from_cold_temperatures_beginning_to_show_up Mites: If you feel mites are the problem the best and quick way to test for this is to take a white sheet of paper and hold it under a branch and tap the branch. This will dislodge some mites and you will see the moving on the paper. They are small - about the size of a period. If you can't see them moving you can try squashing some of the tiny spots. A reddish smear will be from a mite. A hand lens will also help with making a correct identification. Mite feeding will cause a discoloration in the appearance of the needles. They may have a yellowish appearance and then turn to a bronze and finally the needles will drop. The following website will give you more details. http://extension.psu.edu/ipm/program/christmas-tree/pest-fact-sheets/needle-discoloration-and-injury/spruce-spider-mite.pdf There are several fungal issues and diseases that Colorado blue spruce trees can develop over time that will result with needle loss and dead branches. Some diseases are treatable and some are not. Information on common needle cast diseases: http://msue.anr.msu.edu/news/spruce_problems_are_probably_caused_by_more_than_a_single_agent http://msue.anr.msu.edu/news/spruce_tree_problem_shows_symptoms_of_both_needlecast_and_branch_death/ http://www.ag.ndsu.edu/cpr/forestry/needle-cast-diseases-of-spruce-diagnosis-and-treatment Cytospora Canker - This fungus disease tends to infect older spruce trees. You may begin to notice branches dying near the base of the tree first and eventually see it progress upward. You may also see a bluish-white resin on the trunk or branches. The white resin on the branches will resemble bird droppings. There are no effective chemical controls for this disease. The best thing to do is to keep the tree healthy as possible by watering during dry conditions and prune out the diseased branches. The following website will give you details on this condition and with pictures that will help you determine if your Spruce is dealing with this condition. http://www.pestid.msu.edu/LinkClick.aspx?link=Factsheets%2fCytospora.pdf&tabid=218&mid=834 Rhizosphaera Needle Cast - This disease tends to infect older (inner) needles first. The needles turn brown or purple and drop from the tree. If you have a good hand lens you can see the fruiting bodies on the needles. You can prevent new growth from infection by spraying with Chlorothalonil. Daconil 2787 is one brand. The following website gives more details and excellent photos. http://www.pestid.msu.edu/LinkClick.aspx?link=Factsheets%2FRhizosphaeraCS3.pdf&tabid=218&mid=834 Phomopsis - The initial symptoms are very subtle, just a slight discoloration of the needles. Eventually needles may turn brown or purple and drop. In the spring new shoots will expand and then rapidly wilt and die. Cultural control includes removing lower branches that are infected. These branches can be identified by the dead terminal buds. Also keeping the plant well watered during periods of drought is important. Fungicides are available. More information and photos can be found at this website. migarden.msu.edu/uploads/files/e2417.pdf Stigmina - Very little is known about Stigmina. The symptoms are similar and the fruiting bodies could be confused for those of Rhizosphaera. Unfortunately the controls for Rhizosphaera do not appear to be effective for Stigmina. More research is under way to determine if different chemicals or different timings are needed to control this disease. The following website gives some information on Stigmina. http://www.ipm.iastate.edu/ipm/hortnews/2008/2-6/Stigmina.html Setomelanomma - Very little is known about this pathogen. Needles on infected branches will turn yellow, then brown and will drop by the end of summer. Only the needles on the tips of the branches will remain.. More research is underway. Using a professional tree service to apply chemical treatment is important. They have equipment that can effectively cover large trees. Professionals have access to chemicals that we homeowners do not. If your trees are under 13 feet tall you may be able to treat them yourself. Always read and follow the label directions of any product you use. Also, be sure the product is labeled for the pest or the disease, and is labeled for use on spruce. Blue spruces can ‘lose’ their blue color when treated with certain chemicals. This is a lot of information! I know it is confusing. Please write us back if you have more questions. Thank you for using our service.