Modeling white pine blister rust hazard in the Interior Mountain West

This study identifies the coincidence of upper level and surface meteorological conditions conducive to white pine blister rust (WPBR), Cronartium ribicola, infestation at susceptible sites in the Interior Mountain West. The Upper Level Synoptic Index (ULSI) was employed to identify days with upper level flow patterns that were favorable for the transport of rust spores from source WPBR populations in California, Oregon and Washington to targets throughout the region. The results of the upper level investigation were then coupled with a surface evaluation of periods with favorable temperature and humidity for germination of the rust at the targets. The result is a calendar of infestation likelihood for each target point and a map of infestation likelihood for the region. The likelihood of infestation at these target points is compared with the previously examined certainty of infestation at the Sacramento Mountains in south-central New Mexico to yield a relative likelihood of infestation. This technique may now be applied to other white pine populations in western North America, such as those in the Mexican Sierra. This will enable researchers to identify previously undiscovered infestations through surveys focused on the most likely sites for infestation. Additionally, mitigation efforts can be concentrated on pine populations that are most climatologically susceptible to infestation.