year. A laboratory test is necessary to determine the presence of the oak 

 wilt fungus. Any oak trees exhibiting wilt symptoms should be brought to 

 the attention of the city arborist. If new trees continue to die, control 

 measures should be undertaken immediately to prevent spread to healthy trees. 



Old white oak trees exhibiting various stages of decline are more 

 frequently observed on the tablelands around homes rather than in the rav- 

 ines. Many of these trees have been weakened by the fall cankerworm, con- 

 struction injury, excessive soil moisture, as well as drought. Selective 

 pruning out of weakened branches and a program of watering and fertilizing 

 would be beneficial. 



The dumping of grass clippings and leaves over the edges of the 

 ravines is common practice in Highland Park. However, instead of being 

 beneficial, this is HARMFUL, as the debris retains surface moisture, which 

 can cause slumping, and prevent the establishment of new vegetation. Dead 

 trees, especially large ones, should be felled, leaving the stump and roots 

 in place. This will reduce or prevent damage to nearby healthy trees that 

 would occur if the dead trees were felled naturally, such as during a wind 

 storm. Whenever possible, dead trees should be felled so that the trunks 

 fall across the slope of the ravine, rather than up and down the slope. 

 When the latter occurs, the trunks tend to channelize water and rapidly 

 lead to the formation of a small gully. Young trees can be planted to re- 

 place the dead one. 



WHAT TO DO BEFORE PLANTING 



It should be emphasized that, while vegetation is useful and even 

 necessary in a total plan to control erosion, vegetation alone cannot be 

 expected to halt major erosion. In the ravines in Highland Park, the most 

 serious erosion problem has been slumping or sloughing of the upper part of 



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