Invasive Pest Spotlight: Pampasgrass & Jubatagrass
The invasive pest spotlight focuses on emerging or potential invasive pests in California. In this issue, we cover the invasive plants pampasgrass and jubatagrass.
Pampasgrass (Figure 1, top) is a common ornamental flandscape plant that readily naturalizes throughout California's coastal areas and some interior regions. Historically, pampasgrass was planted for erosion control, but it has since escaped cultivation and spread along sandy, moist ditch banks throughout coastal regions of southern California. Pampagrass can also grow in the hot, dry climate of inland areas of California.
A similar-looking invasive grass, jubatagrass (Figure 1, bottom) is more widespread and aggressive and is a major pest in coastal redwood forest areas. Jubatagrass thrives in cool, foggy environments and does not tolerate temperature extremes or drought.
Both pampasgrass and jubatagrass outcompete native plants; a single floral plume can make 100,000 seeds in a year. They create fire hazards with excessive build-up of dry leaves, leaf bases, and flowering stalks. The tough leaves have serrated edges that can easily cut skin.
What can you do?
Plant other ornamental grasses in your garden or landscape. Many species including native grasses can be planted that resemble pampasgrass but aren't problematic. This includes several species of Muhlenbergia: deer grass, white awn muhly, and Lindheimer's muhly. California native Pacific reedgrass grows well on the coast and is deer resistant. For a large, tough bunchgrass, try giant sacaton, a native of the Southwest. Giant wildrye, another California native, will grow into dense stands that attract birds.
For more information, see the University of California Weed Research and Information Center fact sheet at http://wric.ucdavis.edu/PDFs/pampasgrass%20and%20jubatagrass%20WRIC%20leaflet%2099-1.pdf.
Original source: UC IPM Home & Garden Pest Newsletter (Spring 2022) issue.
Belinda Messenger-Sikes is the Urban IPM Writer and Editor for the UC Statewide IPM Program. You can contact her at firstname.lastname@example.org.
- Author: John Madsen
A new invader was found in the Sacramento-San Joaquin River Delta (hereafter “Delta”) by California State Parks, Division of Boating and Waterways (“CDBW”). The new weed is Australian ribbonweed, Vallisneria australis S.W.L. Jacobs and Les. First described as V. gigantea, the taxonomic name has been revised to V. australis (see photos). It has multiple common names, including ribbonweed, eel grass, and others. Native to Australia, it has been spread to New Zealand, Europe, and North America. Ribbonweed is widely sold in both aquatic gardening and aquarium trades.
Ribbonweed forms fertile seed pods, but the predominant form of spread is vegetative by stolon fragments. It forms nuisance growths in irrigation canals in Australia, and invades lakes and rivers in Europe and New Zealand. In New Zealand, it is ranked as a major weed.
Ribbonweed is an herbaceous perennial submerged weed with long strap-like leaves, up to 10 feet long and 2 inches wide. It has leaves that are substantially larger than the North American V. americana, and possesses a rounded leaf tip. It is dioecious, forming separate plants that produce either pollen-bearing or ovule-bearing flowers.
In the Delta, it was found in 2018 at the northern end of the Delta in the Sacramento River. It has since been found in a number of other locations in that region. California Department of Food and Agriculture has rated Australian ribbonweed as a weed of medium concern. They have proposed a B pest weed rating in a report in October 2021, with further action pending.
Currently, no US or California herbicide efficacy information is available. Studies in Australia irrigation canals and studies in New Zealand found diquat (Reward), the dipotassium salt of endothall (Aquathol-K), and the dimethylalkylamine salt of endothall (Hydrothol 191) to be effective for control of ribbonweed. Initial trials in California by CDBW did not find diquat to be effective, but further research is needed.
- Posted by: Gale Perez
The Department of Plant Sciences at the University of California, Davis, seeks an Assistant Professor of Cooperative Extension in Invasive Weed and Restoration Ecology. Faculty in the Department are engaged in developing and disseminating comprehensive basic and applied knowledge regarding all aspects of plant sciences related to managed and natural ecosystems. This position fills a key gap in research and Extension leadership in weed management and ecological restoration in rangelands, wildlands and natural areas.
Rangelands, wildlands and natural areas span about 75% of California's land area and provide critical economic benefits and ecological services. The spread of weedy and invasive plants has altered these systems, severely impacting ecosystem health and agricultural productivity. In the United States, the annual financial impact of invasive plants in rangelands alone has been estimated to be $2 billion. In recent years, funding for ecological restoration has steadily increased for natural and working landscapes. However, an incomplete understanding of the interactions among invasive plants, available restoration practices, and spatial and temporal environmental constraints that affect success/failure has been a fundamental challenge to restoring degraded and highly-invaded landscapes.
- Conduct original, applied research at the intersection of restoration ecology and weed science on working and natural landscapes, ranging from managed to wildland ecosystems (e.g., rangelands, grasslands, woodlands, riparian areas).
- Integrate and apply lessons learned from experimentation and innovation across scales to develop cost-effective restoration and land management practices.
- Provide statewide and national Extension leadership, and share novel, actionable research with land managers, policy makers, conservationists and other key stakeholders via a strong Extension network.
- Serve as a critical network link between Agricultural Experiment Station faculty and Cooperative Extension advisors, as well as with diverse stakeholders (federal and state agencies, regional land managers, non-governmental organizations) throughout California.
For full details and to apply: https://recruit.ucdavis.edu/JPF04766.
To ensure consideration, applications should be received by April 30, 2022.
- Author: Thomas Getts
I have called California Home for the past 6 years since starting this position and the past two summers are unlike any I have experienced in the west. Growing up in Colorado I remember the smokey skys from the Hayman fire and ash raining down from the High Park fire, which blackened my grandparents' property. Moving to Susanville, we had smoke and ash from the 2016 Willard fire, the 2018 Whaleback fire and the 2019 Walker fire, but none of it was unlike what I was used to back home.
Raining ash and thick air was a novel experience to many of my new friends in Susanville, who had grown up in the Midwest. Where friends I had made who were local said 2016-2019 “was nothing” compared to the 65,000 acre Moonlight fire, which filled the Honey Lake Valley with thick smoke for weeks. I thought I had experienced the stress and smoke from wildfires, but was unprepared for the past two summers.
Picture one: Inspiration Point in Susanville California in the middle of the afternoon. Smoke so thick the streetlights came on and it felt like night.
During the summer of 2020 the Hog fire started right up the hill in mid-July. There were planes and lots of resources devoted to control, and while ash rained down from the sky it was just “another fire”. Summer rolled on until one night in mid-August, when I was called to my porch with the CRACK and BOOM of dry lighting. This storm ignited fires throughout the north state all at the same time, suddenly the Sheep fire was raging towards Susanville. With all of the other fires ignited by lighting, there was only a fraction of the resources devoted to suppression. It didn't seem like “just another fire,” the mood was different. People I knew were evacuated, ranchers I worked with were losing infrastructure, trees and feed. The same storm sparked the North Complex, tearing down from Quincy to Oroville chewing 318,000 acres along the way. Smoke from all of the fires was so thick from August through September, hay producers told me their third cutting yields were suppressed from lack of light.
There was little rain or snow over the winter of 2020-2021, typically the wet season. Reservoirs stayed dry, the ground was parched and even the weeds struggled to grow. The lack of moisture affected some of my annual grass research with spotty germination and some seedlings dying before being able to put on a head. Scotch thistle that typically grew 5-6 ft. tall only grew 3ft., where some patches withered never growing at all. It was dry and the start of the 2021 fire season loomed large. It sparked off with the Beckwourth complex that ripped through 105,000 acres in early July, before burning out into the brush and grasslands on the east side of the Sierra.
On July 12th, another fire started way down on Hwy 70 on the border of Butte and Plumas counties in the timber. It was named the “Dixie”. The brush and timber were bone dry and it burned with ferocity through the timber, through towns, and through fire scars from 10 years ago. It burned from mid-July into October, even with an army of brave dedicated firefighters giving it their all for months on end. It had spurts and runs that in the end it had traveled 55 miles north to Old Station, 55 miles northwest to knock on the door of Susanville and 55 miles west to the shores of Honey Lake. It burned nearly 1,000,000 acres stopping just short at 963,000.
Picture Two: Infrared imagery of the Dixie fire from the top of Dyer mountain showing the flames.
I am not a fire scientist, but a weed scientist and this is supposed to be a weed blog. During the countless hours the past two summers I spent eating smoke and praying for high humidity, the thoughts of what plants will repopulate all this burnt acreage have been at the forefront of my thoughts. How many acres had severe fire? Will the perennials resprout? How will the native seedbanks be affected? And what about our suppression efforts?
Weeds are often ruderal species, coming in after disturbance, capturing light moisture and space more efficiently than non-weedy species. When disturbance happens on a roadside, or on a landing pad in a logging operation, the impact of invasive weeds can be great. It creates a prime area for non-desirable plants to gain a foothold and depending on the species, slowly proliferate into undisturbed areas. But what happens when disturbance happens on a grander scale?
There are numerous isolated small populations of invasive weeds throughout the forests which burned. And these pockets of invasives are set up to ramp up their invasion, claiming stake to much larger portions of the landscapes now that it has been disturbed. Winter annual grasses like cheatgrass and medusahead will flourish in the burn, along with other problematic dicot species such as knapweed and thistle.
In 2007 the moonlight fire burned 65,000 acres. It was considered a large fire for the time. Much of the private land was replanted, where lots of the forest service land was left to regenerate back on it's own. When I first started this position of the local Plumas National Forest, botanists were implementing a plan for weed management. Species such as medusahead, Canada thistle, and yellow star thistle had taken hold in large parts of the burn, where on private ground cheatgrass was rampant.
Picture Three: Close up of dozer line disturbance on forested area of the Dixie Fire.
Picture Four: Dozer line through sagebrush on east side of Dixie fire.
While wildfire is a large disturbance, so are some of our firefighting suppression tactics. There were more than 6,000 brave folks fighting the Dixie fire for months. While air tankers are used for suppression when visibility and wind allows, bulldozers scraped Fireline around the clock to protect structures and direct fire. There were nearly 1700 miles of dozer line just within the Dixie fire perimeter, let alone the handline. It is a ripe opportunity for the noxious weed already there to flourish and be moved around by equipment and people. To put this in perspective the length of dozer line in the Dixie Fire is a round trip drive from Sacramento to LA, not once but twice. That is a lot of disturbance, especially considering the 1,700 miles of dozer line is only for the Dixie, and there have been millions of acres burned in over the past two summers.
Picture Six: Dozer line from Dixie and Beckworth fires as of August 23rd.
Being someone who lives in these mountain communities, I am thankful for every mile of dozer line, that may have saved someone's home or life. But the impact of the fires and corresponding suppression efforts on invasive species spread and distributions is real. There have been numerous forest service studies looking at dozer line and increasing invasive species colonization. Generally, there is an association within increased invasive species presence around hand and dozer lines. One FS study in Montana found 73% of hand lines observed had invasive species present within their surveys, significantly higher than their control plots (Black and Landres 2011). Whether the disturbance comes from the fire or the suppression effort, the increase in invasive species through the burn scars will need to be on the minds of managers.
I know I'll be keeping my eye out for new and expanding populations of Noxious weeds in the fire scars over the coming years and praying much of the native vegetation responds favorably.
- Posted by: Gale Perez
From the Journal of Aquatic Plant Management—Special Issue Vol. 59s 2021
An overview of the Delta Region Areawide Aquatic Weed Project for improved control of invasive aquatic weeds in the Sacramento–San Joaquin Delta
Patrick J. Moran, John D. Madsen, Paul D. Pratt, David L. Bubenheim, Edward Hard, Thomas Jabusch, and Raymond I. Carruthers
The 27,540-ha (68,000-acre) Sacramento–San Joaquin River Delta of northern California is the largest freshwater estuary on the western coast of the United States. The Delta provides irrigation water for over $30 billion in crops in the Delta and Central Valley and drinking water for 27 million people, supports $300 million in recreational boating, and includes the ports of West Sacramento and Stockton. The Delta's sloughs, wetlands and riparian habitats host 56 threatened or endangered species. Invasions by nonnative aquatic weeds constitute a major environmental challenge. The USDA–ARS Areawide Pest Management Program focuses on integrated, adaptive control of invasive pests, by supporting implementation of new, science-based control solutions. The Delta Region Areawide Aquatic Weed Project (DRAAWP) was funded from 2014 to 2018 to improve control of floating water hyacinth [Eichhornia crassipes (Mart.) Solms], submersed Brazilian waterweed (Egeria densa Planch.), and riparian arundo (Arundo donax L.) in the Delta. Outputs from the DRAAWP are now informing control of nine aquatic weeds and arundo using adaptive, integrated chemical, mechanical, and biological approaches. Project outputs include improved knowledge of aquatic weed growth and dispersal, models of watershed nutrients, weed control prioritization protocols based on remote sensing and economic cost modeling, and new tools. Outcomes include the implementation of use of new herbicides and biological control agents, improved control efficacy, lowered stakeholder costs, and the leveraging of expertise and funding focused on aquatic weed control for habitat restoration. Benefits include reduced floating aquatic weed coverage, conservation of water and wildlife natural resources, and protection of boating and other economic activities.
Authors (visit the DRAAWP website for the authors' contact information)
- Patrick J. Moran, Research Entomologist, U.S. Department of Agriculture (USDA)–Agricultural Research Service (ARS), Western Regional Research Center, Invasive Species and Pollinator Health Research Unit (ISPHRU)
- John D. Madsen, Research Biologist, USDA–ARS ISPHRU, Department of Plant Sciences, University of California, Davis
- Paul D. Pratt, Research Leader, U.S. Department of Agriculture (USDA)–Agricultural Research Service (ARS), Western Regional Research Center, Invasive Species and Pollinator Health Research Unit (ISPHRU)
- David L. Bubenheim, Senior Scientist, National Aeronautics and Space Administration (NASA)–Ames Research Center
- Edward Hard, Chief, Aquatic Invasive Species Branch, Division of Boating and Waterways, California Department of Parks and Recreation,
- Thomas Jabusch, Senior Environmental Scientist, Invasive Species Program, Habitat Conservation Planning Branch, California Department of Fish and Wildlife
- Raymond I. Carruthers, Research Entomologist and Research Leader (Retired), USDA–ARS ISPHRU