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HomeMy WebLinkAboutAGENDA REPORT 1995 0920 CC REG ITEM 08Lny ITEM CITY OF MOORPARK AGENDA REPORT TO: The Honorable City Council ''cc FROM: Christine Adams, Director of Community Servic uI�Z,6 DATE: September 13, 1995 (Meeting of September 20, 1995) SUBJECT: Consider Status Report of Elm Trees on McFadden and Cornett Streets BACKGROUND There are a variety of mature English Elm trees in the city right -of -way on McFadden and Cornett Streets, which have been maintained by the City since about 1987. In June 1995, Elm Leaf Beetle larvae was discovered in a tree at 300 Cornett Avenue. The tree was removed to prevent further transmission of the larvae to other trees. Approximately two (2) weeks later, the tree at 306 Cornett Avenue was infected with the beetle and was removed, again to prevent or stop the infestation. Staff checked the trees periodically for any infestation and none was found. However, undetectable infestation had occurred and all twenty eight elm trees located on McFadden and Cornett Streets have contracted Dutch Elm Disease, a fungus carried to the trees by the larvae /beetles. The City has contacted Paul Rogers, who is a certified arborist and has provided the City information in the past regarding the health of the High Street Pepper trees. Mr. Rogers is a sub - contractor for Bob's Tree Service, who is contracted by the City for city -wide tree trimming, and is also a contractor for the City of Ojai, as their city arborist. Mr. Rogers came to the site in question and observed the elm trees. A more detailed written analysis by Mr. Rogers will be made available to the City Council prior to the meeting of September 20, 1995. Disease Applicability to McFadden and Cornett Tree The elm trees located on McFadden and Cornett Streets are over 30 years old. Over the past 30 years, prior to the City's assumption of responsibility for the trees, improper trimming practices were used. The studies of the Arbor Association found that "flush" branch trimming next to the tree trunk allowed disease to enter the tree more readily lowering the trees protection defenses. McFadden and Cornett trees all have signs of this practice in the past. Once the City began trimming the trees, branch trimming was accomplished by cutting 3' 6" from the trunk which allows the tree to form a barrier zone where the cut is walled off and new wood cells will form, free of infection. Another problem exists on McFadden and Cornett Street trees. The age of the trees have weakened the codominant stem junctions (where branches meet the trunk). During periods of high winds and heavy rains the codominant junctions break, tearing the branches from the trunk. This allows for an open wound to the cambium allowing infection to the entire tree. Staff recognizes that these trees are important to the aesthetics and charm of this neighborhood. Mr. Rogers report will indicate that the City could take a variety of preventative measures to control the elm leaf beetle. The beetle will not kill the tree, nor will it weaken the tree, as it mainly lives off the leaves. There is a treatment for the elm leaf beetle which is to "band" the trunk of the tree, that is spray the insecticide 'Seven' around 3 - 4' of the trunk, right below where the limbs separate. This should be done in the spring, and will kill most of the larvae who are migrating from the top of the tree to the bottom to pupate. This should be done at least twice during the season. While it is not expensive, it is time consuming. Mr. Rogers overall assessment of the trees on McFadden and Cornett is that while the beetle will not kill the trees and the life of the trees are not threatened, the trees themselves have been poorly trimmed in the past, which has done some damage to the cabium (center of the trunk) of the trees, which with time will cause the trees to weaken. Also, the previous improper pruning has caused the new limbs to come in erratically, which requires the City to prune more often than normal, which increases. Mr. Rogers is recommending that the City consider a long term phasing plan for tree removal. New trees can be planted (different species), and those that are retain, that are in better health, staff can begin the banding program next spring. RECOrMENDATION Receive and File the Report MOON?