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Along the Rio Grande in Texas, tiny insects are taking a big bite out of an invasive weed that competes for limited water resources vital to agriculture and native vegetation. Several years ago, ARS scientists released two insect species as part of a biocontrol program to kill giant reed (Arundo donax).

Aquatic invasive species threaten U.S. freshwater bodies throughout the country. One of the most prevalent and prevailing of these is hydrilla (Hydrilla verticillate), which spans from Florida all the way up to Maine, and as far west as California. The state of Florida alone spent $125 million from 2008 – 2015 to manage aquatic invasive species, $66 million of which went toward managing hydrilla. The Florida Fish and Wildlife Conservation Commission (FWC) is estimated to spend $15 million annually on managing hydrilla. This submerged weed is primarily managed through cost effective, safe aquatic herbicides and more costly mechanical harvesting. Due to the prevalence of hydrilla, understanding stakeholder perceptions regarding its management is critical to its successful control. 

This infographic displays Florida’s stakeholder perceptions around aquatic herbicide and mechanical harvesting usage, which can be utilized as a model for other states as well. Data analysis of 3,000 survey responses concluded that a majority of stakeholders are concerned about both the use of aquatic herbicides and mechanical harvesting.

Giant reed, Arundo donax, is a large, fast-growing invasive grass that has invaded at least 100,000 acres of "riparian" habitat in the southwestern and southeastern U.S. and is present as far north as Ohio and Washington State. Watch this video to learn how ARS researchers are using biocontrol (insects) to reduce the presence of this invasive plant.

The Michigan departments of Environment, Great Lakes, and Energy and Natural Resources confirmed a report of didymo, a nuisance freshwater alga, in a stretch of the Upper Manistee River in Kalkaska County. Also known as rock snot despite its coarse, woolly texture, didymo can grow into thick mats that cover the river bottom. The Manistee River finding marks the first detection of didymo blooms in the Lower Peninsula. In 2015, extensive mats of didymo were found on the Michigan side of the St. Marys River near Sault Ste. Marie in the Upper Peninsula.

If you observe didymo in the water, either as small, cotton ball-sized patches or thick blankets with rope-like strings that flow in currents, take photos, note the location and report it by using the Midwest Invasive Species Information Network, available online at MISIN.MSU.edu or as a downloadable smartphone app. The MISIN smartphone app will take a GPS location point if a report is made at the site; it also will allow you to upload photos with a report. Find more information on didymo and how to identify it at Michigan.gov/Invasives.

Hydrilla, considered one of the world's most invasive aquatic plants, has been detected for the first time in Michigan. The Department of Environment, Great Lakes and Energy confirmed two small populations of the plant in adjacent private ponds on residential properties in Berrien Springs in Southwest Michigan.

The small patches of hydrilla (Hydrilla verticillata) were discovered during routine monitoring following treatment for another invasive plant, parrot feather, which was found in the pond in 2020. Both species are prohibited in Michigan, meaning it is unlawful to sell, possess or import them into the state, and both are on Michigan’s invasive species watch list due to their potential environmental threat. Any suspicious aquatic plants should be reported as soon as possible to EGLE-WRD-AIP@Michigan.gov. Include close-up photos and provide the location of the detection in your report. More information on identifying and reporting invasive aquatic plants can be found at Michigan.gov/Invasives.

In parts of the South, there are stories about an invasive floating weed, which forms such a dense mass that it enables small animals to walk across water. This weed, called giant salvinia, is an exotic fern from South America that invades ponds, lakes, and other waterways in the United States. It damages aquatic ecosystems by outgrowing and replacing native plants that provide food and habitat for native animals and waterfowl.

Agricultural Research Service (ARS) scientists are testing a naturally occurring fungus (Myrothecium spp.) against giant salvinia to help control it. Initial tests have found that the fungus stops this problematic weed from growing and even can kill it.

Alligator weed works it's way into Northern California. ARS researchers are seeking biocontrol agents to control the invasive weed.

The Minnesota Department of Natural Resources has classified 13 high-risk invasive aquatic plants, fish and invertebrates as prohibited invasive species. The DNR classifies invasive species as prohibited to prevent their introduction and spread in Minnesota and to protect the state’s environment, economy, natural resources and outdoor recreation. It is unlawful to possess, import, purchase, transport or introduce prohibited invasive species, except under a DNR-issued permit for disposal, decontamination, control, research or education.

The prohibition on 12 of the 13 species is effective immediately, with publication of the new listings in today’s State Register. Jumping worms will be prohibited invasive species effective July 1, 2024, to provide additional time for outreach to businesses and others who may be impacted by the rule change. A complete list is available on the DNR invasive species laws website.

The NAISMA Classical Biocontrol Committee is excited to announce new peer-reviewed weed biocontrol publications for use by managers and landowners. Subject matter experts are developing a series of factsheets that cover invasive plants and their associated biological control agents in North America. Funding for these factsheets is provided by the United State Forest Service. NAISMA is partnering with iBiocontrol.org to host these publications.
See also: Resources on Biocontrol and Classical Weed Biocontrol Factsheets Released for Landowners and Weed Managers (Press Release - Aug 31, 2022)

The Port of San Diego, along with the Southern California Caulerpa Action Team (SCCAT), the City of Coronado, and the Coronado Cays Homeowners Association (CCHOA), are responding to the discovery of an invasive seaweed scientifically known as Caulerpa prolifera in the Coronado Cays area of San Diego Bay.

In late September, divers found a small patch of Caulerpa prolifera while conducting an in-water pre-construction eelgrass/Caulerpa dive survey as a permit condition for a dock replacement project. Additional patches were discovered nearby during follow-up surveys. The total find within the Cays is about one-quarter of an acre. The SCCAT has prepared a Rapid Response Eradication Plan to address the immediate need to eradicate this invasive species.

Deceptively delicate and fragile in appearance, the Eurasian watermilfoil forms thick mats in shallow areas of a lake, quickly growing and spreading to block sunlight, killing off native aquatic plants that fish and other underwater species rely on for food and shelter. In North America, the plant threatens the diversity and abundance of native plants as well as the ecological balance of lakes and ponds, which in turn adversely affects recreational opportunities. If left unchecked, invasive watermilfoil will spread through a lake, or even to other lakes by transmission. An expert team of USDA Forest Service divers with invasive species and aquatics expertise is focused on rooting out the plant.

The Mississippi River Delta is home to the world’s largest contiguous swath of Phragmites australis, or more commonly known as the common reed. But the plant that can grow to nearly 20 ft. and has been a critical component in stabilizing the state’s coastal erosion is not actually native to Louisiana—well, not entirely. There are multiple P. australis genotypes. P. australis subspecies (ssp.) americanus is the native subspecies in the U.S. and Canada. However, Phragmites australis ssp. australis originated in central Europe and was subsequently introduced to the U.S. where it is now considered to be one of the most problematic invasive species in North America. "Novel genome characteristics contribute to the invasiveness of Phragmites australis (common reed)" in Molecular Ecology and recently featured in an edition of The Scientist, LSU researchers collaborated with Tulane University and the U.S. Geological Survey to study the genomic bases of P. australis and to investigate what exactly makes the invasive reed grass subspecies thrive in wetlands, in comparison to its native counterpart.