estimating economic impact is widely used by economists in measuring the consequences of
existing and potential activities (Lacewell 1995).
To estimate the employment and economic impact to the region of control, market prices
for crops are used (Lacewell 2008). The added irrigated composite acres generate a total revenue
value (gross sales) associated with the biological control program. Similarly, a composite
dryland (non-irrigated) acre for agriculture represents reduced total revenue as it shifts to
irrigated production. The change (increase) in gross revenue associated with the additional
irrigated acreage above the replaced dryland acres provides an estimate of the direct economic
effect and a basis for further analysis. The change in gross revenue is estimated for each year of
the 50-year projection period, where there are greater Arundo control and greater annual benefits
to be realized over time.
Results
Results were generated based on data provided by the USDA-ARS, USDA-NASS, and the
literature for water use, compound rate (i.e., inflation), and discount rate. To date, the results
indicate positive returns and a positive impact to the economy from controlling giant reed.
Plant Growth
The results reveal Arundo donax reaches a maximum of approximately 58,000 acres by
the year 2058, growing at a rate of 2.36% per year with no control from natural insect infestation.
Projecting the effect of natural occurrence of the wasp (natural insect infestation) over the 170
miles prevalent area of infestation results in an estimated effective 1,000 acres of reduced
Arundo, and suggests a minimal impact of the natural wasp without the use of additional (i.e.,