Biological Control of Exotic Weeds in California
Exotic and Invasive Weeds Research
2013 Annual Report
1a.Objectives (from AD-416):
Will collect natural enemies of invasive weeds and evaluate host specificity under quarantine conditions. Will conduct field monitoring of released weed biological control agents. Will conduct research on revegetation of native species in riparian habitats such as Fall River, California.
1b.Approach (from AD-416):
New Natural enemies of weeds such as Eurasian watermilfoil, Arundo & Yellow starthistle will be identified and collected through foreign exploration in countries of origin. For most of the target weeds of interest this will be done working with cooperators at USDA-ARS overseas laboratories, in Europe and China. Following location and proper taxonomic assessment, colonies of these beneficial natural enemies will be established and held under quarantine conditions. Environmental assessments will be written to support requests for field release of these natural enemies by ARS scientists. Once approved by USDA-APHIS & other regulatory groups, these agents will be field released and monitored to determine their establishment and impact on both target and non-target plants. A combination of field & laboratory experiments will be used to identify methods of establishing native species in areas where invasive weeds have been eliminated. The initial focus will be on seed physiology production & dispersal, & artificial seeding of beneficial species.
Research conducted under this Reimbursable Agreement directly supports objective 3 of project 5325-22000-026-00D and Objectives 2, 3 and 4 of project 5325-22000-024-00D. Efforts currently are focusing on the use of biological control to aid in the management of Eurasian watermilfoil in western waterways and on the impact of natural enemies on terrestrial plants such as yellow starthistle and French broom. Additionally, this project has provided resources to help assess overall Eurasian watermilfoil growth and development in infested waterways and to assess growth potential of native plants that can compete with weeds and slow the invasion process. Specific experimental studies on Zannichellia palustris (horned pond weed) have focused on natural plant phenology, growth and reproduction in critical waterways and on the seed germination and establishment processes in spring fed rivers. These efforts have led to restoration studies with the aim of augmenting Z. palustris within critical habitats in an effort to block further invasion of invasive milfoil.