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United States Department of Agriculture

Agricultural Research Service

Research Project: Biological Control of Exotic Weeds in California

Location: Exotic and Invasive Weeds Research

2012 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.


3.Progress Report:

This research addresses objective 4, which focuses on providing weed management methods for land managers in the Western United States. ARS scientists completed research activities on the biological control of both French and Scotch Broom being conducted in cooperation with the Bureau of Land Management and the US Army, in Fort Lewis, Washington. Studies focused on the interaction of biological control with both mechanical (mowing) and cultural (burning) practices in large management areas on Fort Lewis, Washington, overseen by the Nature Conservancy. Two publications were submitted on this work and additional new work was initiated on the biological control of Cape ivy. Cape ivy research focused on the impact assessment of potential biological control agents on limiting weed growth and development and on finalizing additional host-specificity testing requested by the USDA-APHIS Technical Advisory Group that recommends regulatory approval of new biological control agent releases into North America. Based on these data, two regulatory petitions were submitted to APHIS in the spring of 2012. These petitions requested the importation of a biological control fly and moth to help control Cape ivy in California. As the Cape ivy quarantine testing project was completed, ARS scientists in Albany, California, began a new effort on the assessment of Euhrychiopsis lecontei, the milfoil weevil, to help control Eurasian watermilfoil within California and other western states. New aquatic mesocosms and aquatic rearing systems were developed and weevil/ milfoil colonies established. Weevil numbers are currently being multiplied from a small colony established from the Feather River of California with the goal of evaluating the weevil’s effectiveness under cold water conditions as needed to control milfoil in areas such as the Fall River of California, and other western states including Oregon, Idaho, Montana, Washington and Alaska.


Last Modified: 4/23/2014
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