Projected gains in rotation-age volume and value from fusiform rust resistant slash and loblolly pines

Midrotation data from large block plots of resistant and susceptible slash (Pinus elliottii Engelm.) and loblolly pine (Pinus taeda L.) were used in c ombination with the Georgia pine plantation simulator growth model to provi de projected gains per hectare in volume and Value generated by resistance to fusiform rust (Cronartium quercum (Berk.) Miyabe ex Shirai f.sp. fusifor me). The difference in the projected volume production between the resistan t and susceptible planting stock of slash pine was larger than the differen ce between resistance levels in loblolly pine. The increases in projected v olume and the reductions in percent infection of the resistant stock led to large differences in the value of the resistant and susceptible planting s tock. At a 6% real discount rate, plantations of resistant slash pine were on average worth between 40.2 and 89.8% more than plantations of susceptibl e slash pine. Plantations of resistant loblolly were on average worth betwe en 6.1 and 40.3% more than plantations of susceptible loblolly pine. Howeve r, the marginal value of rust resistance in loblolly was not significantly different from zero under the assumption that economic differences are only due to volume losses and not losses due to product degrade.