(A) Whenever it is found with reasonable certainty that a tree has Dutch elm disease or oak wilt, the Tree Inspector shall proceed as follows. If the Tree Inspector finds that there is potential for infection of other oak or elm trees, he or she shall notify the owner of the property on which the nuisance is found. The Tree Inspector will specify a reasonable date before which the nuisance must be abated. The Tree Inspector shall immediately report the action to the Street and Park Superintendent and, after the expiration of the time limit set forth by the notice, the Tree Inspector may proceed to abate the nuisance. The cost of the abatement, plus a $300 administrative fee, shall be assessed against the owner of the property involved, or against the property itself in the same manner as a special assessment in accordance with M.S. §§ 429.011 et seq., as they may be amended from time to time.
(B) High risk elm trees. High risk elm trees shall be those trees that are dead, barren or have extensive wilt (30% or more of the tree is wilted). The trees shall be identified and marked prior to June 25. These high risk trees shall be removed within 20 days of notification of the property owner.
(C) Low risk elm trees. Low risk elm trees shall be those trees that show early stages of infection in June or subsequently during the growing season with those symptoms not progressing beyond the 30% wilting point. Every reasonable effort shall be made to have low risk trees removed within 20 days of notification of the property owner, but in no case shall it be later than April 1 of the year following the appearance of symptoms.
(D) Oak trees.
(1) All oak trees within the city diagnosed as having oak wilt shall be isolated from neighboring healthy oak trees of the same species by chemical or mechanical disruption of common root systems to prevent root graft transmission of the oak wilt fungus.
(2) To control overland spread of oak wilt, the pruning of oaks shall be avoided during the most susceptible period of infection, from April 15 until July 1. If wounding is unavoidable during this period, as in the aftermath of a storm or when the tree interferes with utility lines, a tree wound dressing shall be applied immediately.
(a) Prevention.
1. To prevent the oak wilt fungus from producing spores and to prevent overland spread of this fungus, any diseased material of the red oak group wilting in July and August of one year shall be declared hazardous the following spring, from April 15 until July 1.
2. Any hazardous oak wood to be used as fuel wood or to be salvaged for other purposes must be debarked or else completely covered by heavy plastic (four mil or greater) from April 15 until July 1 of the year following the appearance of symptoms. After this time, there is no danger of spore production and the wood does not need to be covered.
3. Any branch greater than two inches in diameter of the red oak group determined to be hazardous and not salvaged shall be disposed of by burning, chipping or removal to an authorized dump site prior to April 15 of the year following the appearance of symptoms. Dead standing red oaks that have advanced beyond the potential for spore production need not be removed except where they constitute a hazard to life and/or property. The Tree Inspector will advise accordingly.
4. Stumps of trees of the red oak group removed due to oak wilt shall be completely covered, removed or debarked to the ground line to eliminate all possibilities of spore formation and overland disease spread.
(b) White oaks. Trees of the white oak group (such as white oak, bur oak, bicolor oak) diagnosed as having oak wilt shall be isolated by root graft disruption as previously stated. Diseased material originating from the trees will rarely ever support spore formation and salvaged material therefore will not require special treatment to prevent overland spread. Standing trees of this group showing early symptoms of oak wilt may be saved by removing affected branches. The Tree Inspector will advise accordingly.
(Ord. 419, passed 3-9-1992)