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HomeMy WebLinkAboutRorke 163 Serrano Hts Canopy Restoration Arborist Report - Canopy restoration September 23, 2021 For: John Rourke 163 Serrano Heights San Luis Obispo, CA Plant ID Quercus agrifolia – Coast Live Oak Task Canopy Restoration Plan Background: Owner pruned four (4) Coast Live Oaks (CLO) for view. Trees are extensively pruned leaving stubs and large pruning wounds. The city of San Luis Obispo has required a canopy restoration plan to grow the canopy back. The average canopy width (diameter) would have likely been 12 feet. The average height likely 12 feet from bottom of canopy to top of canopy. Observations as a group: Extensive canopy reduction was done on all four trees. The tree closest to the neighbor’s house has more structure and canopy remaining than the other three, and will likely recover more rapidly than the other three. Very large cuts were made, and stubs were left as trees were topped. Two trees have very little foliage left. The trees with less foliage are also currently under a very large Bark Beetle attack as holes and ooze are noted all over trunks and scaffold. Vehicles have been driven and parked below these trees and the soil is quite compacted. Conclusion: Much work will need to be done to restore the canopy. The two trees that have Bark Beetle may not survive and the city will likely require mitigation if these die, because the Bark Beetle infestation is a result of improper pruning. Recommendations made will need to be followed carefully in order to restore the canopy. Recommendations for five years: Immediate – 1) There shall be no parking, vehicle or foot traffic, storage or other activity that can compact soil within the tree’s Critical Root Zone (CRZ). Soil may need to be physically aerated with a soil auger if the soil is already too compacted. 2) Trees that have Bark Beetle shall have trunks treated with a bark beetle insecticide and bark penetrant to kill larvae and prevent more damage. 3) Soaker hoses or in line drip emitter drip line shall be used so that the entire CRZ is moistened to a depth of no less than 16 inches every month. This type of watering shall occur until rainfall adequately moistens soil to that depth. If drought continues, this type of watering may need to continue through 2022 per arborist’s guidance. 2022 – 1) Watering may need to continue this year, especially if we are in a drought. Arborist will make the decision of when and how much water. 2) Trees shall be reassessed in March for health and progress. All four trees shall be treated with soil injected nutrient and beneficial microorganism root zone treatment. 3) Bark Beetle insect treatment shall be made in April. This treatment shall be applied to all four trees as a preventative. 4) A late summer inspection shall be made to assess progress and health. 2023 – 1) Watering will likely be done on an as need basis. 2) Trees shall be reassessed in March for health and progress. 3) All four trees shall be treated with soil injected nutrient and beneficial microorganism root zone treatment. 4) A late summer inspection shall be made to assess progress and health. At this time trees can also be assessed for late season pruning. 2024 – 1) Trees shall be reassessed in March for health and progress. 2) At this time if the arborist feels there is enough progress (growth, health, canopy size etc.) a final report will be made, and guidelines given for future care and pruning. If trees have not sufficiently progress, the 2023 schedule schedule will be followed. Guidance and recommendations will be given after each assessment. These guidelines and recommendations shall be followed as directed. Under no circumstance is any pruning to be done without the authorization of the arborist. Canopy growth will come slowly at first and gradually increase. The arborist will set guidelines and timing for any pruning done. Failure to follow these guidelines may reduce the chances of the trees’ survivability or complete restoration of the canopy. Any questions that arise concerning following these guidelines or deviating from them shall be addressed to the arborist. These guidelines/recommendations are meant to restore the canopy that was destroyed. The City of San Luis Obispo can choose to fine or request mitigation measures such as tree replacement or other requirements if these guidelines/recommendations are not followed. It is incumbent on the owner of these trees to follow what the arborist has requested. Sincerely Chris Stier, ISA Certified Arborist, #WE9262-A *Assessment was made with observation, history and sound arboricultural and horticultural knowledge. It is always possible that other, or different problems exist that may contribute to the destabilization, decline and death of trees. Further evaluation may be warranted if the steps above do not work. Pathology tests and other lab analysis are available. ‘ The canopy of this tree was likely 12’x12’. The recommendations and guidelines are meant to restore that size canopy. These spots are damage and resulting ooze caused by Bark Beetle. Over pruning attracts these pests. Heavy populations can kill trees. The city may choose to mitigate in some way if the tree dies.