weed science

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Highlights from the Western Society of Weed Science Annual Meeting 2023

As soon as I learned that the Western Society of Weed Science‘s annual meeting was going to be held in Boise in 2023, I began making plans to attend. I had attended the annual meeting in 2018 when it was held in Garden Grove, California and had been thinking about it ever since. It’s not every year that a meeting like this comes to your hometown, so it was an opportunity I knew I couldn’t miss. The meeting was combined with the Western Aquatic Plant Managment Society‘s annual meeting, so consider that a bonus.

The first meeting of the week was the general session where introductions are made and various updates are given. There were two keynote addresses as well. One highlight for me was learning about Women of Aquatics, which is a support group for women that work in aquatic sciences. Because this and so many other scientific fields tend to be male dominated, it’s good to see organizations offering support and creating community to help address some of the challenges women face when working in fields where they are underrepresented. Another highlight was Matt Germino‘s talk about fire ecology in the sagebrush steppe. Due to decades of overgrazing and the introduction of a suite of invasive annual grasses (among other factors), fire has become far more common in our region than it once was. The sagebrush steppe is not adapted to frequent fire, which is part of what makes restoration work so difficult. In 2015, a megafire (referred to as the Soda Megafire) occurred in the Owyhee Mountains, burning around 279,000 acres of sagebrush steppe. Restoration efforts after the fire have been well researched, and such efforts continue to this day. Research opportunities like this are helping us improve the way we address this issue in the West, and I hope to spend future posts elaborating further on this topic.

After the general ssession, I attended a few of the talks that were happening in the various breakout sessions. One was about climate change trends in the western U.S. No surprise, temperatures are on the rise, and along with that will come changes in the way we receive our preciptation (which has already been documented). Our region is expected to see more rain and less snow, and rain events are expected to be of shorter duration but with heavier rainfall. Snowpack is expected to continue to decrease, and drought is expected to become more extreme, which ultimately leads to more fire weather days. None of this is great news, but it’s important to understand what we are in for. I also attended a talk about non-target impacts that can arise from certain herbicde treatments used to control bird cherry (Prunus padus) in Alaska, which brought me back to my time attending the Alaska Invasive Species Workshop in Anchorage.

Posters!

The following day, the breakout sessions continued, and dozens of talks were given throughout the day. It’s impossible to attend them all, and unfortunately a few of the talks that I really wanted to hear were cancelled. One interesting talk that I’m glad I got to see was about liquid-applied cellulosic mulches used to replace polyethylene sheet mulches (black plastic) in strawberries and other crops. The results seen so far seem promising, and I’m eager to follow this topic to see where it goes and hopefully even try it out myself one day.

During the meeting, there were also a series of posters on display that summarized research being doing by some of the attendees. I didn’t get a chance to read them all, but a few standouts included posters about using prescriptive grazing to help control tall oatgrass (Arrhenatherum elatius) populations in Colorado, using an electrical current to help manage weeds in blueberry farms, and weed seed predation by ground beetles in diversified wheat production cropping systems. If a poster is about some form of novel or underused method of weed management, I’m definitely going to read it.

bur chervil (Anthriscus caucalis) in downtown Boise

It might seem a little odd for me to be attending meetings like this, especially since I don’t work as a weed scientist or in weed management, and much of what is discussed, namely presentations about all the various herbicide treatments used in rangelands, turfgrass, and large-scale agriculture, don’t concern me (nor do they really interest me). Talks like this are what you would expect to hear at a weed science conference, so despite not being my thing, I appreciate that such talks often include discussions about herbicide resistance and the responsible use of herbicides, climate change, drought and responsible water use, and adaptive management approaches to weed control. I’m not sure when I’ll get a chance to attend this meeting again – it may be another 5 years or more – but whenever the opportunity presents itself, I’ll be there.

Next Up: Botany 2023 is coming to Boise in July. I’ll see you there!

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The Weeds in Your Bird Seed

With February comes the return of the Great Backyard Bird Count, a weekend-long, worldwide, bird counting event that Sierra and I have enjoyed participating in for the past few years. While you can choose to count birds anywhere birds are found, part of the appeal of the event is that it can be done from the comfort of one’s own home simply by watching for birds to appear right outside the window. If there are bird feeders in your yard, your chances of seeing birds are obviously improved. Watch for at least fifteen minutes, record the number and species of birds you see, then report your sightings online. It’s for science!

Feeding and watching birds are popular activities. In the United States alone, as many as 57 million households put out food for birds, spending more than $4 billion annually to do so. While there are a variety of things one can purchase to feed birds – suet, berries, mealworms, etc. – the bulk of that money is likely spent on bags of bird seed (also referred to as bird feed). Bird seed is a relatively cheap and easy way to feed a wide variety of birds. Unfortunately, it’s also a great way to introduce new weeds to your yard.

Bird seed contaminated with noxious weed seeds is not a new problem. It has been a concern for decades, and some countries have taken regulatory steps to address the issue. In the United States, however, there are no governmental regulations that address weed seed contamination in bird seed.  With this thought in mind, researchers at the University of Missouri screened a large sampling of bird seed mixes to determine the number and species of weed seeds they harbored, as well as their viability and herbicide resistance. Their results were published last year in Invasive Plant Science and Management.

The researchers examined 98 different bird seed mixes purchased from retail locations in states across the eastern half of the U.S. The seeds of 29 weed species were recovered from the bags, including at least eight species of grasses and several annual and perennial broadleaf weeds. 96% of the mixes contained one or more species of Amaranthus, including Palmer’s amaranth (Amaranthus palmeri), which was found in 27 mixes and which the researchers refer to as “the most troublesome weed species in agroecosystems today.” About 19% of amaranth seeds recovered germinated readily, and five of the seed mixes contained A. tuberculatus and A. palmeri seeds that, once grown out, were found to be resistant to glyphosate, the active ingredient in a commonly used herbicide.

Redroot pigweed (Amaranthus retroflexus) is one of several weedy amaranth species commonly found in bird seed mixes (illustration credit: wikimedia commons)

The seeds of grass weeds were found in 76% of the bird seed mixes and included three species of foxtail (Setaria spp.), as well as other common grasses like large crabgrass (Digitaria sanguinalis) and barnyardgrass (Echinochloa crus-galli). Bird seed ingredients that seemed to favor grass seed contamination included wheat, grain sorghum, and proso millet, three crops that are also in the grass family. No surprise, as grass weeds are difficult to control in crop fields when the crop being grown is also a grass.

After amaranths and grasses, ragweed (Ambrosia artemisiifolia) was the third most common weed found in the mixes. This was a troubling discovery since populations of this species have shown resistance to a number of different herbicides. Moving ragweed to new locations via bird seed could mean that the genes that give ragweed its herbicide resistance can also be moved to new locations. Kochia (Bassia scoparia), another weed on the Weed Science Society of America’s list of top ten most troublesome weeds, was also found in certain bird seed mixes, particularly when safflower was an ingredient in the feed.

A similar study carried out several years earlier at Oregon State University found the seeds of more than fifty different weed species in ten brands of bird feed commonly sold at retail stores. Ten of the weeds recovered from the mixes are on Oregon’s noxious weed list. Both studies demonstrate how bird seed can be a vector for spreading weed seeds – and even new weed species and herbicide-resistant genes – to new locations. Weeds found sprouting below bird feeders can then potentially be moved beyond the feeders by wind and other dispersal agents. Weed seeds might also be moved to new locations inside the stomachs of birds.

Addressing this issue can be tackled from several different angles. Growers and processors can improve their management of weed species in the fields where bird seed is grown and do a better job at removing weed seeds from the mixes after they are harvested. Government regulations can be put in place that restrict the type and quantity of weed seeds allowed in bird feed. Further processing of ingredients such as chopping or shelling seeds or baking seed mixes can help reduce the presence and viability of weed seeds.

Processed bird feed like suet is less likely to harbor viable weed seeds (photo credit: wikimedia commons)

Consumers can help by choosing bird feed that is processed or seedless like sunflower hearts, dried fruit, peanuts, suet cakes, and mealworms, and can avoid seed mixes with a large percentage of filler ingredients like milo, red millet, and flax. Attaching trays below feeders can help collect fallen seeds before they reach the ground. Bird seed can also be avoided all together, and feeding birds can instead be done by intentionally growing plants in your yard that produce food for birds. By including bird-friendly plants in your yard, you will also have a better chance of seeing a wide variety of birds during the Great Backyard Bird Count.

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Introducing Weeds of Boise

Weeds are the wild flora of our cities. Their occurrence and continued existence is not directly reliant on humans in the same way that the plants in our yards, parks, gardens, and other green spaces are. They may take advantage of the disturbance that we cause when we stir up the soil or cease maintenance in a particular spot, and they certainly appreciate the runoff from our sprinklers and the free rides their seeds get on our pets and ourselves, but they don’t need us looking after them to survive. They get by on their own whether we approve of them or not. Most may not be native to the area, but their presence is natural – undirected and involuntary – and for this reason I consider them to be a valid component of our urban flora.

If you visit a natural area outside of our cities, you are likely to find a field guide associated with that region that will help you identify many of the plants found there. However, such a field guide is not likely to exist for the plants found in a vacant lot or an urban roadside near you. Sure, there are plenty of general weed identification guides, some of which may be specific to where you live, but they are often focused on agricultural/horticultural weeds or weeds found in natural areas outside of the built environment. Few show weeds in an unmaintained urban setting the way that Peter Del Tredici’s book or Maggie Herskovits’ zine do. Clearly we need more resources that identify and document our urban floras.

Weeds of Boise is an attempt to begin that process for my corner of the world. After coming across websites like The Weedalouge (cataloging the wild plants of Philadelphia), Weeds of Melbourne (“a visual glossary of the weedy heritage of Melbourne, Australia”), and Spontaneous Urban Plants (an attempt to map weeds in urban areas around globe), I decided to start the process here in Boise, Idaho. My goal is to select locations across the city and inventory the weeds found there at different times of the year. I will keep a running list of what I find and photograph as many plants as I can. I will make a separate blog post for each location and maintain a link for each post in the Weeds of Boise page. The blog posts will be updated as I collect more data for each site. Over time I hope to have a more clear picture of what weeds are found here and how they are distributed.

Because many of these plants are cosmopolitan, the weeds found in my area are likely similar to the ones found in yours, but there may be some unique differences. If more projects like this are undertaken, we will have a better idea of the similarities and differences among our urban floras. Upon closer observation, we are likely to make some interesting discoveries. Who knows what we might find once we really start looking at these obnoxiously ubiquitous but otherwise completely ignored plants?

Weeds of Boise is also a reminder that you can botanize anytime anywhere. You don’t have to jet off to some remote location to see plants. It’s likely that there are wild plants growing right outside your front door – each one with a unique name and story and just as worth getting to know as any other.

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Highlights from the Western Society of Weed Science Annual Meeting

Earlier this month, I went to Garden Grove, California to attend the 71st annual meeting of the Western Society of Weed Science. My trip was funded by an Education and Enrichment Award presented by the Pahove Chapter of the Idaho Native Plant Society. It was a great opportunity for a weeds-obsessed plant geek like myself to hang out with a bunch of weed scientists and learn about their latest research. What follows are a few highlights and takeaways from the meeting.

General Session

Apart from opening remarks and news/business-y stuff, the general session featured two invited speakers: soil ecologist Lydia Jennings and historian David Marley. Lydia’s talk was titled “Land Acknowledgement and Indigenous Knowledge in Science.” She started by sharing a website called Native Land, which features an image of the Earth overlayed with known “borders” of indigenous territories. By entering your address, you can see a list of the tribes that historically used the land you now inhabit. It is important for us to consider the history of the land we currently live and work on. Lydia then compared aspects of western science and indigenous science, pointing out ways they differ as well as ways they can be used in tandem. By collaborating with tribal nations, weed scientists can benefit from traditional ecological knowledge. Such knowledge, which has historically gone largely unrecognized in the scientific community, should receive more attention and acknowledgement.

David Marley was the comic relief. Well-versed in the history of Disneyland, he humorously presented a series of stories involving its creation. Little of what he had to say related to weed science, which he openly admitted along the way; however, one weeds related story stood out. Due to a lack of funds, the early years of Tomorrowland featured few landscape plants. To make up for that, Walt Disney had signs with fake Latin names created for some of the weeds.

Weeds of Range and Natural Areas

I spent the last half of the first day in the “Weeds of Range and Natural Areas” session where I learned about herbicide ballistic technology (i.e. killing plants from a helicopter with a paintball gun loaded with herbicide). This is one of the ways that Miconia calvescens invasions in Hawaii are being addressed. I also learned about research involving plant debris left over after logging. When heavy amounts of debris are left in place, scotch broom (Cytisus scoparius) infestations are thwarted. There was also a talk about controlling escaped garden loosestrife (Lysimachia punctata) populations in the Seattle area, as well as a few talks about efforts to control annual grasses like cheatgrass (Bromus tectorum) in sagebrush steppes. Clearly there are lots of weed issues in natural areas, as that only covers about half the talks.

Basic Biology and Ecology

On the morning of the second day, the “Basic Biology and Ecology” session held a discussion about weeds and climate change. As climate changes, weeds will adapt and find new locations to invade. Perhaps some weeds won’t be as problematic in certain areas, but other species are sure to take their place. Understanding the changes that are afoot and the ways that weeds will respond to them is paramount to successful weed management. This means documenting the traits of every weed species, including variations between and among populations of each species, so that predictions can be made about their behavior. It also means anticipating new weed species and determining ways in which weeds might exploit new conditions.

No doubt there is much to learn in order to adequately manage weeds in a changing climate. An idea brought up during the discussion that I was particularly intrigued by was using citizen scientists to help gather data about weeds. Similar to other organizations that collect phenological data from the public on a variety of species, a website could be set up for citizen scientists to report information about weeds in their area, perhaps something like this project in New Zealand. Of course, there are already a series of apps available in North America for citizen scientists to report invasive species sightings, so it seems this is already happening to some degree.

Teaching and Technology Transfer

A highlight of the afternoon’s “Teaching and Technology Transfer” session was learning about the Wyoming Restoration Challenge hosted by University of Wyoming Extension. This was a three year long contest in which thirteen teams were given a quarter-acre plot dominated by cheatgrass with the challenge to restore the plant community to a more productive and diverse state. Each team developed and carried out their own strategy and in the end were judged on a series of criteria including cheatgrass and other weed control, plant diversity, forage production, education and outreach, and scalability. Preliminary results can be seen here; read more about the challenge here and here.

And so much more…

Because multiple sessions were held simultaneously, I was unable to attend every talk. I also had to leave early on the third day, so I missed those talks as well. However, I did get a chance to sit in on a discussion about an increasingly troubling topic, herbicide-resistant weeds, which included a summary of regional listening sessions that have been taking place in order to bring more attention to the subject and establish a dialog with those most affected by it.

One final highlight was getting to meet up with Heather Olsen and talk to her briefly about her work in updating the Noxious Weed Field Guide for Utah. This work was aided by the Invasive Plant Inventory and Early Detection Prioritization Tool, which is something I hope to explore further.

If you are at all interested in weeds of the western states, the Western Society of Weed Science is a group you should meet. They are fun and friendly people who really know their weeds.

See Also: Highlights from the Alaska Invasive Species Workshop 

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Introducing Invasive Species

The terms “invasive” or “invasive species” get thrown around a lot. They are frequently used to describe anything that is “misbehaving,” or acting in a way that doesn’t fit our idealized vision for how a landscape should look and function. Oftentimes a species that is introduced (by humans) or is not native to an area automatically gets labeled invasive, even if it isn’t acting aggressively or having any sort of dramatic impact on the ecosystem. It is an alien species in an alien environment; it has invaded, therefore it is invasive.

image credit: cartoon movement

image credit: cartoon movement

Determining what is actually invasive in what location and at what time is much more complex than that. We do our best to understand the natural features and functions of ecosystems, and we single out any species, whether introduced or not, that is acting to upset things. That species is considered invasive and, if the goal is to restore the natural balance, it must be controlled. To what degree a species should be controlled depends on the degree that it is upsetting things. Ultimately, it comes down to human judgement. Hopefully that judgement is based on the best available evidence, but that isn’t always the case.

But we are getting ahead of ourselves. What I mostly want to accomplish with this post is to introduce the concept of invasive species and point you to a selection of resources to learn more about them. I defined invasive species in a post I wrote back in August 2015, so I will repeat myself here:

“Invasive species” is often used inappropriately to refer to any species that is found outside of its historic native range (i.e. the area in which it evolved to its present form). More appropriate terms for such species are “introduced,” “alien,” “exotic,” “non-native,” and “non-indigenous.” The legal definition of an invasive species (according to the US government) is “an alien species that does or is likely to cause economic or environmental harm or harm to human health.” Even though this definition specifically refers to “alien species,” it is possible for native species to behave invasively.

These terms refer not just to plants but to all living organisms. The term “noxious weed,” on the other hand, is specific to plants. A noxious weed is a plant species that has been designated by a Federal, State, or county government as “injurious to public health, agriculture, recreation, wildlife, or property.” A “weed” is simply a plant that, from a human perspective, is growing in the wrong place, and any plant at any point could be determined to be a weed if a human says so.

Invasive species are easily one of the most popular ecological and environmental topics, and resources about them abound – some more credible than others. Here is a list of places to start:

That should get you started. There are, of course, numerous books on the subject, as well as a number of peer-reviewed journals dedicated to biological invasions. You should also be aware that IUCN maintains a list of the Top 100 World’s Worst Invasive Species and that there is a National Invasive Species Awareness Week, which is quickly approaching. This episode of Native Plant Podcast with Jamie Reaser (executive director of National Invasive Species Council) offers an informative discussion about invasive species, and a search for “invasive species” on You Tube brings up dozens of results including this brief, animated video:

 

I want to believe that we are doing the right thing when we make concerted efforts to remove invasive species and restore natural areas, but I’m skeptical. The reason why I have chosen to spend an indefinite amount of time exploring the topic of invasive species is because I truly want us to get it right. Yet I don’t even know that there is a “right.” It seems to me that there are endless trajectories – each one of them addressing different objectives and producing different outcomes. In a way we are playing God, regardless of which approach we take. We are making decisions for nature as if we know what’s best for it or that there even is a “best.”

Humans have had major impacts on virtually every square inch of the planet and have been placing our fingerprints on every ecosystem we touch since long before we became the humans we are today, and so it is difficult for me to envision a planet sans humans. It is also difficult for me to buy into the idea that our planet should look as though humans haven’t touched it (i.e. pristine). Because we have been touching it – for hundreds of thousands of years. Efforts to rewind time to before introductions occurred or to hold an ecosystem in stasis, securing life for only those species that “belong” there, seem noble yet fanciful at best and misguided, arrogant, and fruitless at worst.

To be the best conservationists we can be, we probably need to find a middle ground regarding invasive species – not a deter and eliminate at all costs approach, but also not a complete surrender/all are welcome and all can stay stance. Somewhere in between seems reasonable, acknowledging that the strategy taken will be different every time based on the location, the species in question, and our objectives. Of course, none of my beliefs or opinions on this topic (or any topic for that matter) are fully formed. I am trying to do my best to maintain an open mind, seeking out the best information available and following the evidence where it takes me. A topic as complex as invasion biology, however, is never going to be easy to finalize one’s opinions on, and so this journey will be boundless. I hope you will join me.

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Last but not least, here are two articles that discuss updating our approach to dealing with invasive species: