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Noxious and Invasive Plants |
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Contacts:
Charla Hollingsworth
Response and Recovery- Plant Pathogens and Weeds
National Science Program Leader
Ron Sequeira
Scientific Information, Trade Issues, and Risk Analysis
National Science Program Leader
Hot Topics |
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Herbicide and Cultural Control of Invasive Plants
The CPHST lab in Fort Collins has an active invasive weed control program. The primary goal of the program is to improve weed control for federal noxious weeds and other target species selected by the State Plant Health Directors. The field and lab studies include the testing the use of selective herbicides, commercial adjuvants, and alternative spraying systems. Herbicide treatments are matched to the local climate and weed species conditions. Replicated field studies have been conducted on benghal dayflower (FL), cogongrass (FL, AL), common tansy (SD), leafy spurge (CO), onionweed (AZ), and yellow toadflax (SD). New field studies will test herbicide treatments for sweet resinbush and fountain grass (AZ) and giant hogweed (ME). In addition, a prototype magnetic sprayer is being tested for spray drift reduction and improved weed control. (Contact Charla Hollingsworth)
Restoration of Invasive Plant Infestations
Restoration of treated invasive weed infestations is an important component of a comprehensive weed control program. Broad spectrum herbicides used for invasive weed control may create barren patches when spraying large weed infestations. The CPHST Fort Collins lab has conducted an onionweed study that included spot spraying to encourage existing native vegetation to re-establish and fill in the barren areas. Other restoration methods used by our lab include the use of selective herbicides, such as the sulfonylureas, which control broadleaf weed species but do not harm grass species. We have had very good success in re-establishing grasses in our herbicide studies with common tansy and yellow toadflax by using selective herbicides. A third restoration method used by this lab is re-seeding treated areas with grasses or cover crops to establish a rapid growing ground cover or beneficial legume. We have had good success in establishing legume and sudangrass cover crops after controlling cogongrass and benghal dayflower in FL and AL, where there is abundant rainfall. (Contact Charla Hollingsworth)
Development of a Predictive Weed Screening Model
As part of the Q-37 regulations overhaul, CPHST is developing a screening tool to identify plants that are likely to be weedy or invasive in the United States. This tool or weed risk assessment considers not only biological traits such as reproduction and dispersal, but also impacts to agricultural, natural, and anthropogenic systems, and history of invasiveness elsewhere in the world. CPHST is testing different models with a set of U.S. species with known invasive behavior to determine which models are most accurate. In the future, staff will incorporate a procedure into the screening process that will help us evaluate the consequences of uncertainty on the outcome of the screening procedure for any given plant. (Contact Ron Sequeira)
Ecology of Invasive Plants. Long term monitoring of individual patch expansion rates of perennial species would provide insight into the spatial and temporal dynamics of invasive weed communities. Many invasive plant species are perennials that spread vegetatively (through rhizomes, stolons, etc.) and form distinct patches. Patch expansion rates are a primary indicator of the invasiveness of a species. Field data on patch expansion has been collected for approximately 10 – 12 invasive weed species in seven states in the past two years. Patch expansion rates vary from 0.4 to 13.3 ft2/day, with most species averaging about 2- 6 ft2/day over a summer growing season. This data may be used for spatial analysis or for justifying weed control programs (Contact Charla Hollingsworth)
Weed risk assessment. Invasive weeds cause serious damage to our natural resources and agriculture. Existing invasive weeds are often introduced as plants intended for propagation or unintentionally introduced as contaminants. To prevent introduction of new invasive weeds CPHST risk analysts evaluate the potential of foreign plant species to become damaging invasive weeds, often resulting in regulations that prohibit entry. (Contact Ron Sequeira)