03-28-85 Agenda & Packet - Laserfiche WebLink

Home Browse Search

1984 FORESTRY PROGRAM SUMMARY • DUTCH ELM DISEASE , OAK WILT AND HAZARDOUS TREE REMOVALS The year 1984 was one of increases in both Dutch elm disease and oak wilt. Dead and dying elms removed numbered one hun- dred twenty ( 120 ) ; forty ( 40 ) or 33 percent, were Chinese or Siberian elms. Twenty-two ( 22 ) woodpiles were found to con- tain elm or diseased red oak wood and promptly removed . The annual elm loss rate increased from last year' s .70 per- cent to 1 . 36 percent. This is nearly a two-fold increase in elm removals. Most municipalities saw a comparable rate of increase . Researchers have pointed to better winter survival ( heavy snow conditions) by the elm bark beetles as a principal reason for the increases. Additionally, a possible mutation of the disease itself is being studied. Non-diseased trees removed from parks and boulevards numbered six. Foremost among these trees was a 41" diameter cottonwood removed from Silver View Park. Trenching as a means of oak wilt control was not utilized in Mounds View in 1984 for reasons of mechanical breakdown and lack of crew ( autumn ) . • NORWAY MAPLE WINTER KILL Extreme weather conditions in the fall and early winter of 1983 led to serious death and dieback in many of the City' s Norway maple and white ash varieties. Especially hard hit were the newly planted trees in parks and public areas. Eighty-four ( 84 ) of these trees were removed from City parks. What could be termed a lack of "hardiness" was generally responsible for the damage . An unusually mild fall , coupled with a early and severe winter did not allow the trees proper preparation for dormancy. The result was the death of the trees " living" combium layer , lack of nutrient and water translocation and a visible cracking or sloughing of the tree' s bark . Often these visible symptoms, especially in the case of partial damage , were not evident until growth had com- menced in the spring . Partially damaged trees, though some- what disfigured, had healthy foliage . Some of these will recover in due time ; others will start a slow cycle of de- cline . Trees on private property displayed the same incidence of dam- age with most older trees surviving and most younger trees severly damaged or dead. All totalled , one hundred twelve ( 112 ) trees were removed from parks because of the above men- tioned damage , vandalism and root failure .