Pacific Southwest

Title: Aerial and ground surveys for mapping the distribution of Phytophthora ramorum in California

Author: Mai, Jeffrey A.; Mark, Walter; Fischer, Lisa; Jirka, Amy

Date: 2006

Source: In: Frankel, Susan J.; Shea, Patrick J.; and Haverty, Michael I., tech. coords. Proceedings of the sudden oak death second science symposium: the state of our knowledge. Gen. Tech. Rep. PSW-GTR-196. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture: 345-360

Station ID: GTR-PSW-196

Description: Since 2001, the USDA Forest Service and California Polytechnic State University, San Luis Obispo have been collaborating for early detection and monitoring of the occurrence of Phytophthora ramorum, the pathogen known to cause sudden oak death (SOD). The effort consists of annual aerial surveys to map hardwood mortality in overstory tree species including coast live oak (Quercus agrifolia), tanoak (Lithocarpus densiflorus), Shreve oak (Quercus parvula var. shrevei) and California black oak (Quercus kelloggii). These aerial surveys are followed by ground surveys to locate and sample both symptomatic overstory and understory host plants. Over the past few years the surveys have focused on early detection within minimally infested counties or counties with no known occurrence of P. ramorum but share a common border with regulated (infested) counties. The team of cooperators includes assistance from the University of California (UC), the California Department of Food and Agriculture (CDFA), county agricultural commissioners and cooperation from numerous private and public entities. Success in the program can be looked at in at least two ways, 1) by identifying new disease infestations and 2) by not finding new disease infestations. Over the past four years, the combination of aerial survey and ground confirmation efforts have identified new fronts of infection and mapped the distribution of P. ramorum within counties, or portions of counties, not previously known to have the disease (including recent expansion into southern Monterey County and new occurrences in Lake County). Following aerial surveys, ground surveys are targeted within select areas to check for infestations that would expand the current range of P. ramorum. All areas mapped from the air within counties adjacent to currently infested counties are checked on the ground. Within minimally infested counties, ground surveys are targeted toward those areas in the county not known to be infested. Established sampling protocols are followed to determine if P. ramorum symptoms are evident in any of the susceptible plant species present. All samples are shipped to the appropriate laboratory for confirmation of P. ramorum as well as other Phytophthoras. Results from aerial and ground surveys conducted over the last four years were compiled and evaluated for over 1,000 discrete areas mapped from the air and hundreds of sites visited on the ground showing the distribution of P. ramorum-caused hardwood mortality across the landscape.

Keywords: aerial surveys, ground surveys, Phytophthora ramorum, sudden oak death

View and Print this Publication (480 KB)

Publication Notes: 

• We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
• This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
• You may send email to pubrequest@fs.f ed.us to request a hard copy of this publication. (Please specify exactly which publication you are requesting and your mailing address.)

 Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

Citation

Mai, Jeffrey A.; Mark, Walter; Fischer, Lisa; Jirka, Amy  2006.  Aerial and ground surveys for mapping the distribution of Phytophthora ramorum in California.   In: Frankel, Susan J.; Shea, Patrick J.; and Haverty, Michael I., tech. coords. Proceedings of the sudden oak death second science symposium: the state of our knowledge. Gen. Tech. Rep. PSW-GTR-196. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture: 345-360.