In 1996, the city of Sacramento Department
of Neighborhood Services, the Sacramento Tree Foundation, and the
University of California received a grant from the California Dept.
of Pesticide Regulation to implement an IPM program. Each of the
agencies was therefore able to hire extra help to implement our
monitoring methods in Sacramento. In addition, the group began to
look at the development of new methods for large urban areas as
well as to evaluate new and existing control methods (Dahlsten
et al., 1998). Previous management for ELB consisted of systemic
insecticides applied to all susceptible elms throughout the city
on a calendar basis [E].
The first goal of the program was to base
treatment decisions on monitoring. ·
- The monitoring program began with a small
pilot study in 1995 with 4 small sites being monitored at egg
peak to determine if treatment was needed. ·
- The number of trees managed using the
monitoring program grew each year until all susceptible trees
were monitored in 1999. ·
- City and STEP personnel were trained
in the use of the degree-day model and ELB monitoring techniques.
- All susceptible elms were mapped and
apprx. 20% of these were chosen as sub-sample trees. ·
- Monitoring has been very successful at
reducing the number of trees treated. Between 1995 and 1999 only
11.3% of the trees in the monitoring areas required treatment.
By treating only the areas with significant numbers of beetles
present, monitoring has drastically reduced chemical use when
compared to the previous strategy of treating all susceptible
trees (Fig. 4). ·
- The damage prediction model successfully
predicted damage from ELB in the first and second beetle generations
and data from Sacramento fit well in the model (Fig. 5).
[E] Before the monitoring program, all trees were
injected with a systemic insecticide on a calendar basis.
Fig. 4 The number of elms treated has declined
as more elms were managed under the monitoring program in Sacramento,
CA from 1994 through 1999.
Fig. 5 Proportion of samples with egg clusters
present vs damage for individual trees, generation 1, 9 years combined.
Sacramento data fits well in the previous model.