§ 91.41  DECLARED SHADE TREE PESTS, CONTROL MEASURES, AND CONTROL AREAS.
   (A)   Oak Wilt.
      (1)   Definition.OAK WILT DISEASE is a shade tree pest and is defined as any living or dead tree, log, firewood, limb, branch, stump, or other portion of a tree from any species of the genus Quercus existing within the control area defined that has bark attached and that exceeds three inches in diameter or ten  inches in circumference and contains to any degree any spore or reproductive structures of the fungus Ceratocystis fagacearum.
      (2)   Control measures. Control measures that may be taken to abate oak wilt disease are:
         (a)   Installation of a root graft barrier. A root graft barrier can be ordered installed to prevent the underground spread of oak wilt disease. The city will mark the location of the root graft barrier. The barrier disrupts transmission of the fungus within the shared vascular systems of root grafted trees. The barrier is created by excavating or vibratory plowing a line at least 42 inches deep between any oak tree infected with oak wilt disease and each nearby and apparently healthy oak tree within 50 feet of the infected tree.
         (b)   Removal and disposal of trees.
            1.   On property zoned for residential and commercial use.
               a.   On property that is zoned residential and commercial the city may mark for removal trees that have the potential to produce spores of the fungus Ceratocystis fagacearum. After, and in no case before, the installation of the root graft barrier and no later than May 1 of the year following infection, all marked trees must be felled. The stump from such felled trees must not extend more than three inches above the ground or, if taller, must be completely debarked.
               b.   If, however, after the city prescribes the location for a root graft barrier, the city determines that installation of the barrier is impossible because of the presence of pavement or obstructions such as a septic system or utility line, the city may mark for removal all oak trees whether living or dead, infected or not and located between an infected tree and the marked barrier location. These marked trees must be felled and disposed of no later than May 1 of the year following infection. The stump from such felled trees must not extend more than three inches above the ground or, if taller, must be completely debarked.
            2.   On all other property.
               a.   On all other property, the city may mark for removal all oak trees whether living or dead, infected or not and located between an infected tree and the marked barrier location. These marked trees must be felled and disposed of no later than May 1 of the year following infection. The stump from such felled trees must not extend more than three inches above the ground or, if taller, must be completely debarked.
               b.   All wood more than three inches in diameter or ten inches in circumference from such felled trees must be disposed of by burying, debarking, chipping, or sawing into wane-free lumber, or by splitting into firewood, stacking the firewood, and immediately covering the woodpile with unbroken four-mill or thicker plastic sheeting that is sealed into the ground until October 1 of the calendar year following the calendar year in which the tree was felled, or by burning before May 1 of the year following infection. Wood chips from infected trees may be stockpiled or immediately used in the landscape.
      (3)   Control area. The control area for oak wilt disease is defined as all lands within the boundaries of the city.
   (B)   Emerald Ash Borer.
      (1)   Definition. EMERALD ASH BORER is a shade tree pest and is defined as an insect that attacks and kills ash trees. The adults are small, iridescent green beetles that live outside of trees during the summer months. The larvae are grub- or worm-like and live underneath the bark of ash trees.
      (2)   Control measures. Control measures that may be taken to manage and abate Emerald Ash Borer are those currently advised by the University of Minnesota Extension website at http://www.extension.umn.edu/garden/insects/find/emerald-ash-borer/#management and the Emerald Ash Borer Information Network at http://www.emeraldashborer.info/resources.php.
      (3)   Control areas. The control area for Emerald Ash Borer is defined as all lands within the boundaries of the city.
   (C)   Dutch Elm Disease.
      (1)   Definition. DUTCH ELM DISEASE is a shade tree pest and is defined as a disease of elm trees caused by the fungus Ophiostoma ulmi or Ophiostoma novo-ulmi, and includes any living or dead tree, log, firewood, limb, branch, stump, or other portion of a tree from any species of the genus Ulmus existing within the control area defined that has bark attached and that exceeds three inches in diameter or ten inches in circumference and could contain bark beetles or any spore or reproductive structures of the fungus Ophiostoma ulmi or Ophiostoma novo-ulmi.
      (2)   Control measures. Control measures that may be taken to abate Dutch elm disease are:
         (a)   Use of fungicide. Fungicides may be effective in preventing Dutch Elm disease when injected into living trees that do not already show symptoms of Dutch Elm disease. Fungicide injections on private lands are optional and, if performed, are at the landowner's expense.
         (b)   Removal and disposal of trees. Prompt removal of diseased trees or branches reduces breeding sites for elm bark beetles and eliminates the source of Dutch Elm disease fungus. Trees that wilt before July 15 must be removed within 20 days of detection. Trees that wilt after July 15 must be removed by April 1 of the following year. Diseased trees not promptly removed will be removed by the city at the landowner's expense. Wood may be retained for use as firewood or saw logs if it is debarked or covered from April 15 to Oct. 15 with four-mill plastic. The edges of the cover must be buried or sealed to the ground. 
      (3)   Control area. The control area for Dutch elm disease is defined as all lands within the boundaries of the city.