The URL can be used to link to this page

Home My WebLink About9A - Oak Wilt Report MEETING DATE: AGENDA #: PREPARED BY: PRESENTER: AGENDA ITEM: DISCUSSION: 4646 Dakota Street SE Prior Lake. MN 55372 CITY COUNCIL AGENDA REPORT JULY 19, 2010 9A AL FRIEDGES, PARKS AND FLEET SUPERVISOR AL FRIEDGES, PARKS AND FLEET SUPERVISOR CONSIDER APPROVAL OF THE 2010 OAK WILT INSPECTION REPORT Introduction The purpose of this agenda item is to consider the 2010 Oak Wilt Disease Report. Historv Oak trees are one of the most valued trees in Minnesota. They are a major component of native woodlands in and around many Minnesota communi- ties. The very existence of oak trees in some areas is threatened by a fatal disease that attack oak trees - Oak Wilt. Oak wilt is caused by a fungus and is responsible for killing large numbers of oaks annually in Minnesota. Symptoms Oak wilt is easily identified in the red oaks by rapid wilting of affected trees. After the first symptoms appear a tree will wilt completely in two weeks. Of- ten diseased trees occur in groups or centers of infection. The trees wilt from the top of the crown down and individual leaves wilt from tips to bases, turning green and then brown. Infection Process The oak wilt fungus spreads in two ways. Most commonly new infections are the result of the fungus moving from infected to healthy oak trees via grafted root systems. Trees growing as far as 50 feet apart may be root grafted together. The other means that Oak Wilt can be spread is by insects. The only way that the fungus can cross highways, rivers or open areas is by insects, commonly known as picnic beetles. These beetles are not attracted specifi- cally to oaks and cannot wound trees. They must visit fresh wounds that are less than a few days old and are made during the summer months. These small beetles infect a healthy tree and only when fresh wounds are present. Although less than 10% of the oaks dying from oak wilt are believed to be infected this way, it is the only way a new pocket of oak wilt will start. Root transmission is responsible for 90% of the trees becoming infected from oak wilt. Roots of adjacent oaks are often grafted together, forming a common root system. The oak wilt fungus spreads through a diseased trees vascular system, down into the roots, then through the root grafts into adja- cent trees, infecting them as well. R:\Council\2010 Agenda Reports\07 19 10\Oak wilt report. doc Trees in the red oak group are highly susceptible to oak wilt and do not re- cover if infected. Once symptoms appear, the tree will wilt completely with- in two weeks. If other red oaks are nearby, steps should be taken imme- diately to prevent spread into healthy trees. When oak wilt symptoms are first noticed in red oaks, the fungus has already spread throughout the tree and into the roots. In fact, the fungus often has already infected the root sys- tem of adjacent trees, although they may still look healthy because visible symptoms are not yet apparent. Current Circumstances Oak wilt has been present in Prior Lake for approximately ten years. The affected area (ground zero) is located along Fish Point Road between Highway 13 and 160th Street and has been spreading in this area yearly through root graft. The topography in this area is hilly and has resulted in costly removal fees for the residents that have the diseased trees. The cost of removals has compounded efforts to slow down or eliminate the spread of oak wilt, most noticeably this year. For example, of the seven residents that were cited for oak wilt on June 15, 2010 for a total of 18 trees, only one resident complied within the 20 days allowed to complete the removals. City Ordinance Section 602 establishes a procedure for dealing with Oak Wilt Disease. The City Council has determined that the loss of trees grow- ing upon public property would substantially depreciate the value of property within the City and impair the safety, good order, general welfare and con- venience of the public. It is declared to be the intention of the Council to control and prevent these conditions in the ordinance. Currently the Parks Division of the Public Works Department conducts three oak wilt inspections during the summer months. On July 9, 2010 several additional trees with oak wilt were observed. Conclusion Section 602.501 of the Hazardous and Diseased Tree Ordinance states that diseased trees shall be treated, if feasible, and any diseased trees which are not treated shall be removed within twenty days from the date on which they were certified as diseased. ISSUES: Those untreated diseased trees which have not been removed within the twenty day limit shall be cited and, absent any agreement to the contrary with the City, shall be removed either by contract. The cost of removal shall be assessed against the property in the case of removal at City expense. (To date two of the residents who have not removed their trees have re- quested this method of removal and payment.) Several residents cited for Oak Wilt Disease have indicated they are unable financially to pay for removal of the trees in accordance with the ordinance. In accordance with the ordinance the City should proceed with removal of the trees. In order for staff to proceed with removals to following steps need to be completed: 1) City Council directs staff to prepare a resolution ordering abatement of the Oak Wilt. 2) Notice of intent to consider a resolution ordering the abatement at a public hearing is published and mailed by certified mail to the resi- dents no less than 4 days prior to the meeting. R:\Collncil\2010 Agenda Reports\0719 10\Oak wilt report. doc 2 3) City Staff will solicit quotes for completion of the work. 4) Public Hearing is held on abatement at which time residents can tes- tify with regards to the abatement. 5) City Council passes a resolution ordering the abatement. 6) The trees are removed and the detailed costs for each property are recorded. 7) The costs of the abatement shall be assessed against the properties as detailed in section 602.704. Staff has identified oak wilt in the Fish Point Road area between Highway 13 and 160th Street for years. Over the past several years Staff has worked with residents to complete removal of the infected trees. In an effort to be "customer friendly" the City has allowed for extensions to removal deadlines by residents. Unfortunately the spread of oak wilt in this area continues to increase every year through root graft. Delays in removing trees may be contributing to this spread. In addition to the immediate removal needed to help stop the further spread of oak wilt in this area, staff recommends assisting the residents both through education of oak wilt and setting up a containment plan. The con- tainment plan would include a decisive plow line route to help eliminate the spread of oak wilt through root graft transmission. This proactive approach will not only slow the spread of oak wilt in the Fish Point Road area, but could also be beneficial to keeping this disease from spreading into the many other areas of the Community with large populations of oaks. (See exhibit A.) FINANCIAL IMPACT: Should the City elect not to proceed with abatement, the Oak Wilt will con- tinue to expand killing more oak trees on neighboring properties. Staff estimates that the cost of the removal per property identified in 2010 will range between $1 ,000 and $15,000 depending on difficulty of removal due to steep terrain. There are seven properties that have not complied with the notice and will need to be abated at this time. Should the City proceed with abatement, the costs will need to be paid by the City upfront and recovered through assessments ranging from one to five years depending on the cost per City Policy. The funding source for the abatement costs would be the Contingency Fund. ALTERNATIVES: 1. Direct staff to publish a public notice and prepare a resolution for ab- atement to be considered at the August 2nd City Council Meeting. 2. Direct staff to work with the residents in the affected area to educate the effects of oak wilt and assist in the preparation of a containment plan to stop the spread of oak wilt 3. Table this agenda item for a specific reason and provide staff with direc- tion. 4. Deny this agenda item for a specific reason and provide staff with direc- tion. RECOMMENDED #1 and #2 MOTION: Reviewed by: Frank Boyles, City Manager RICollncil12010 Agenda Reportsl07 19 1O\Oak wilt reportdoc 3 fxh ~ !;c+ A 2010 Oak Wilt 5923 ~ 11:.313 15m !ID1 599J I 19329 WOODSIDE Pp : c: W 1:.353 UI 56i'1 &>91 n: iJ 0 If<3i'9 0 0 ;;,i'n 15393 ~ 0 ..J 15701 -- HU~?,N S' 'SE :;~ 5517 5593 :.311 9329 5il'9 ~71~1 ti39i! 5117-~ 5955 5370 w UI o n: !z 5 0- X UI u: 15655 This drawing is neither a legally recorded map nor a survey and is not intended to be used as one. This drawing is a compilation of records, information, and data located in various city, county, and state offices, and other sources affecting the area shown, and is to be used for reference purposes only. Scott County is not responsible for any inaccuracies herein contained. If discrepancies are found, please contact the Scott County Surveyors Office. Map Scale 1 inch = 354 feet N W+E S IS%ott Map Date 7/12/2010 lill3/" /' 15233 -- .-. 153~ Concentrated Oak Woods 10 y .-J y ~ - r :.~---y;/ ~ ~ . ~"I ... ( ",I ;: ~ '-, - . Lv ). .: t. ~ " u ~ 'l '" J .l.....a - .~ ~i_ j .... ;> ( I, ~- .~ S'-v...~O fit>' n 1 . ~ , U .r~ ~ . '" .1 .. This drawing is neither a legally recorded map nor a survey and is not intended to be used as one. This drawing is a compilation of records, information, and data located in various city, county, and state offices, and other sources affecting the area shown, and is to be used for reference purposes only. Scott County is not responsible for any inaccuracies herein contained. If discrepancies are found, please contact the Scott County Surveyors Office. Map Scale 1 inch = 0.6 mile Map Date 7/12/2010 N W+E S ''").~. ...~. _:...... (,Scott