2_Exhibits A, C & D - Laserfiche WebLink

Guide to Care of California Native Oaks HortScience,Inc. Page 3 Supplemental irrigation may be needed for trees whose root systems have been impacted. However, oaks are accustomed to dry summer conditions and tend to develop fatal root diseases if irrigated frequently during the summer. For trees that would benefit from extra water, we suggest extending the period of natural rain while preserving the annual summer drought. We do so by irrigating in late spring (May and June) and early fall (September - October). However, no irrigation should take place in July and August. Irrigation should wet the top 2 - 3' of soil. We suggest creating basins to contain irrigation water on flat sites (Fig. 1), or using slow drip emitters or soaker hoses on sloped sites(Fig. 2). Soaker hoses can be allowed to run overnight. Check the depth of water penetration with a shovel. Oak trees should not be irrigated within 10' of the trunk, or more frequently than once a month. Irrigating frequently around the trunks of mature oaks during the summer leads to development of root diseases that can kill the tree. rst 4.4 dikt T r 6ti Keep area ; '� .&z. , ''; around ;•' Fill basin �' Soaker trunk dry -, . �- _ •-� A with water co:1J hoses Fig. 1: Construct earthen Fig. 2: For trees on slopes, soaker berms to create watering hoses placed in concentric rings basins around trees on flat can be used to provide ground. An inner berm keeps supplemental water. Mulch can be water away from the trunk. placed over the hoses. ore than 25% of the foliage of the tree. Previously shaded branches that are exposed to the sun are easily damaged from sunburn. Pruning to reduce the weight on heavy horizontal limbs should remove small diameter branches (less than 3"), and retain foliage along the length of the branch. Trees need to be inspected annually to evaluate structural stability and need for pruning. Most old oaks have considerable amount of decay in the trunk and major branches. They need to be inspected regularly by a professional to determine if weight needs to be removed from weak areas to reduce the risk of branch or trunk failure. Pruning and cabling should be undertaken by qualified arborist. Tree pruning companies must carry the California State Contractors License for Tree Services (#C61/D49). Any pruning should be performed by a Certified Arborist or Tree Worker and adhere to the Tree Pruning Guidelines of the International Society of Arboriculture. Irrigation irrigation per month). No plants should be installed within 10' of the trunk of the tree. A list of species appropriate for use under oaks is listed in Table 1. 4. Irrigation systems must be very carefully designed to avoid trenching through roots. No irrigation lines shall be placed under the driplines of HortScience,Inc E 325 Ray St. I Pleasanton, CA 94566 phone 925.484.0211 I fax 925.484.50961 www.hortscience.Com ll not be placed within the TREE PROTECTION ZONE, either temporarily or permanently. Any modifications must be approved and monitored by the Consulting Arborist. 2. All demolition, excavation and construction within the dripline of trees shall be done using the smallest equipment possible. The Consulting Arborist will identify where hand excavation may be required. Motorized equipment shall not be used within the TREE PROTECTION ZONE. 3. Prior to excavation for the demolition and construction the tree may require root pruning outside the TREE PROTECTION ZONE by cutting all roots cleanly to the depth of construction. Roots will be exposed by either: pulling soil away from the tree by digging , normally 54"above grade. A multi-branched tree, which has