HomeMy WebLinkAbout18 OLEANDER REPLACE 09-15-97DATE:
SEPTEMBER 15, 1997
Inter-Com
NO. 18
9-15-97
TO:
FROM:
SUBJECT:
WILLIAM A. HUSTON, CITY MANAGER
PUBLIC WORKS DEPARTMENT/FIELD SERVICES DIVISION
OLEANDER PLANTS REPLACEMENT - EAST TUSTIN
RECOMMENDATION:
Council information only, receive and file the report.
FISCAL IMPACT:
No cost at this time. However, the cost associated with the replacement of the remaining plants will require a
future appropriation from the City Council.
DISCUSSION:
With the development of the Tustin Ranch area, an extensive system of landscaping was installed to provide an
aesthetically pleasing environment to the residents of this area. This landscaping was also utilized to provide a
visual and auditory screen for the residents and individuals utilizing the sidewalks, bikeways and roadways. One
of the plants utilized extensively throughout this area is the Nerium oleander, a large evergreen shrub reaching a
height of 12 feet. Staff estimates there were approximately 8,500 Nerium oleander plants throughout the Tustin
Ranch landscaping. In the last two to three years the Oleander plants have been infected with a disease (Oleander
Leaf Scorch) which attacks the plants and kills them within two years, by slowly choking the plant~ ability to
transmit water through the stems. This disease is transmitted from plant to plant by an insect called a Glassy-
Winged Sharpshooter..This insect, which had not previously existed in California, was found in abundant amounts
in Orange and Riverside Counties. It is believed that this insect came into California in the egg stage on plants.
The glassy-winged sharpshooter appears to be well established and thrives on a variety of host plants including
citrus, eucalyptus, crape myrtle, oleander and many other agricultural, ornamental and weed plants. Because of the
large range and variety of plant hosts and the wide distribution of the sharpshooters, eradication of this insect is not
feasible..
Staff estimates there are approximately 8,500 Oleander plants in the Tustin Ranch landscaping. The largest
concentration of plants is along Tustin Ranch Road, Jamboree Road, Bryan Avenue, and Irvine Boulevard, which
have a total of 5,500 plants. In Spring 1997, the City began the first stage of the Oleander replacement by planting
approximately 2,160 plants at intersections throughout the Tustin Ranch area at a cost of $43,200.00. Prior to'
Spring 1997, other replacement projects had been undertaken at other intersections, which resulted in the removal
and replacement of another 300 plants. This leaves a balance of approximately 6,100 plants that remain to be
removed and replaced.
Staff is working with Robert Goto, Landscape Architect, on the appropriate variety and sizes of plants that can be
utilized to replace the remaining Oleanders. Mr. Goto is very familiar with the landscape design in the Tustin
Ranch area, having prepared the landscaping plans for numerous developments in Tustin Ranch. The plant
material to be utilized will need to complement the existing landscaping, be tolerant of the soil and weather
conditions, and have a tolerance to disease and pest problems.
This last issue is extremely important because once the Oleanders are removed, the principal source of food for
these pests is eliminated.
Because these insects exist on a large' variety of plants, the replacement plants might become infected as well. The
University of Califomia, Riverside and Caltrans are attempting to fund a project to study this issue, as well as the
effectiveness of certain insecticides on the sharpshooter. Any information that is developed from this study can be
utilized in the selection of the appropriate plant material.
Staff and the Architect are m the process of reviewing the options. Upon completion of this process, we will
develop a list of viable alternatives, a recommended schedule for implementation, and estimated costs. This
reformation will be brought before Council for further review.
Director of Pubhc Works/City Engineer
TDS:MP:CR:OLEANDERREPLACE98.DOC
Martin Pastucha
Manager, Field Services