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1987 END OF YEAR FORESTRY SUMMARY <br /> DUTCH ELM AND OAK WILT DISEASES <br /> • Another decrease in the incidence of dead and diseased elms was <br /> recorded for 1987. A total number of 64 elms was removed, <br /> significantly down from last year ' s loss of 84 . Eighteen ( 18 ) of <br /> this year 's 64 elms were "Chinese" or "Siberian" . <br /> The number of diseased oaks increased slightly to 57 from last <br /> year 's count of 52. Many of these oaks were small trees of less than <br /> 8 inches in diameter. <br /> The 1987 annual rate of elm loss (per remaining population) was 0. 74. <br /> This compares favorably to the last two years ; ( 0. 96 in 1986) and <br /> ( 1 . 54 in 1985) . This is the lowest recorded loss rate in the last <br /> decade in Mounds View. Control program success and weather-related <br /> factors aside, these figures would seem to indicate that a re- <br /> inventory of the remaining elm population is in order to recertify <br /> statistical credibility. Generally speaking, a control program <br /> with less than 2. 0 percent annual elm loss on a consistant yearly <br /> basis would seem to indicate great program success , inaccuracy of <br /> elm population figures or both. <br /> Seven ( 7) woodpiles containing 20 yards of elm or diseased oak wood <br /> were identified and removed. <br /> OTHER TREE DISEASES <br /> • The year 1987 was exceptionally dry with adequate rainfall occurring <br /> on only a couple of occasions. Generally speaking, such a year <br /> results in fewer incidences of leaf spotting fungi . Virtually no <br /> anthranose was reported on oaks, maples or ash. <br /> Cytospera canker was observed in some older Colorado spruce, <br /> fireblight bacteria in apple trees and black knot fungus on <br /> ornamental cherries. Some apple scab fungus was seen on flowering <br /> crabapple trees once high humidity and late season rains prevailed. <br /> DAMAGING TREE INSECTS <br /> Damage due to various tree insects were reported by residents <br /> throughout the spring and summer. <br /> Of greatest importance was once again the birch leaf miner. The <br /> feeding activity of this pest on an annual basis will be leading to <br /> the premature death of many of the area 's birch trees. More <br /> information on the control of this pest will be made available to <br /> the public (via newsletter, local paper, etc. ) as research results <br /> become known. <br /> Elm leaf miner was active in several pockets producing symptoms that <br /> are sometimes confused for Dutch elm disease. The damage of this <br /> insect is rarely of consequence to the health of the host elm tree. <br /> • <br />