Better Know a Scientist: Weed Scientist Dr Lynn Sosnoskie

People: we’re in for a special treat today. One of my favorite tweeple, Dr Lynn Sosnoskie, has graciously accepted a Q&A for “Better Know a Scientist”. Dr Sosnoskie is a scientist at UC Davis’ Plant Science Department where she does research on weed control. She has a PhD in weed science from Ohio State and has done research at University of Wisconsin, as well as the University of Georgia.

I did a bit of crowd-sourcing and asked on my private Facebook profile what questions my friends and family would like to ask, and there were some excellent recommendations. My comments throughout reflect the fact that we installed fake grass in a good chunk of our yard after two trucks full of mulch created a weed-free, yet visually unappealing and fire-hazardous yard.  So here we go!

Q: Weed research seems to be a fairly random field to study. I don’t think I’ve ever met a kid or high-school student who dreams of becoming a weed researcher when they grow up. What led you to this field?

Dr Lynn Sosnoskie

A: It’s a long and random story, but I’ll try to sum it up nicely. As a biology major (during my undergraduate degree) we took a Botany class field trip to Longwood Gardens in Kennett Square, Pennsylvania. I fell in love with the place and, more importantly, fell in love with plant science. Following my graduation, I was lucky enough to intern at Longwood and a few other gardens/arboretums in the greater Philadelphia area. While attending a pest control lecture on dandelions, I just knew that I wanted to go further into the plant protection arena. After a brief detour (my MSc. in Plant Pathology), I was fortunate to get a research assistantship in a weed ecology lab at Ohio State, where I earned my PhD. I enjoyed my pathology years, but I was just always more interested in plant-plant interactions as opposed to plant-pathogen interactions.

[Biochica’s note: if only everyone was inspired by dandelions instead of being filled with rage...]

Q: What are you currently researching?

A: I have quite a few projects underway. Firstly, I am finishing up some studies looking at seed production in hairy fleabane (Conyza bonariensis) following failed herbicide applications. Hairy fleabane is a common weed in our orchard and vineyard systems in California  and many plant populations have developed resistance to glyphosate (which has been the most frequently applied herbicide in perennial systems). Hairy fleabane is a real bane to growers because it produces LOTS of wind-dispersed seed, which are responsible for both new and continuing infestations [Biochica’s note to Lynn: I see what you did there… “The Hairy fleabane is a real bane”... Awesomeness!!]. To return to my earlier statement about seed production following herbicide failures, I am interested in understanding how the plants that escape weed control efforts might affect the development of weed populations.

I am also looking at the growth and development of junglerice (Echinochloa colona), which is also a pest of California orchard systems (almonds, walnuts, pistachios etc..., under differing environmental and disturbance conditions to look at its potential to invade other cropping systems. A chunk of my time is also spent researching the biology, ecology and management of field bindweed (Convovulus arvensis), which is a significant problem in processing tomatoes.

Q: Why do some herbicides develop weed-resistant pests more quickly than others?

A: The development of resistance is a function of many different factors...the phenomenon really should be looked as an interaction between the weed, the cropping system, AND the herbicide. The simple answer to your question is ‘overuse of certain products in time and space’ and the simple solution, in turn, is that we should avoid using a single herbicide mechanism of action, exclusively, to control weeds. Yes, we have to ensure that we use our herbicides responsibly (see this post by Dr. Andrew Kniss (University of Wyoming)), but we also need to understand the current constraints on our cropping systems that might limit our abilities to diversify (see this post, also by Andrew Kniss). And let’s not forget the weeds, themselves. Certain biological characteristics appear to be more commonly associated with the development of herbicide resistance. Dr. Jodie Holt (University of California, Riverside) and some colleagues published an interesting paper in PLOS ONE looking at the ‘Taxonomic and Life History Bias in Herbicide Resistant Weeds’. They found that evolved resistance is more common in certain plant families (i.e. the Amaranthaceae, Brassicaceae, and Poaceae) than in others. They also reported that annual weed species were found more often in the list of weeds with evolved herbicide resistance, suggesting that the length of a species’ life cycle is a contributing factor. Although they didn’t have enough data to link other traits (i.e. seed production or outcrossing rate) to the development of herbicide resistance, many other sources have suggested that these characteristics can facilitate the evolutionary process.

[Biochica’s note to Lynn: does this mean that I can ask the spouse to go kill the weeds as soon as possible, because if he doesn’t they’ll evolve to become herbicide tolerant? Don’t answer that! That’s what I’m going to tell him...]

Q: What beneficial weeds do we often overlook when thinking about weeds?

A: I think the biggest beneficial weed on (almost) everyone’s mind is milkweed, which is a host for monarch butterflies. Many people might ask themselves: “Should I be actively planting milkweed on my property?” Only you can answer that question. Talk to your local extension agents or master gardeners if this species is an appropriate addition for your yard. At the very least they can direct you to the appropriate resources.

Q: How often have you had to say “No, I’m not *that* kind of weed scientist”? Do you have a poster of Cheech in your office?

A: A lot. Whenever one of my professional societies (California Weed Science Society, Western Weed Science Society, Weed Science Society of America) has a meeting somewhere, and people see our name badges, there is the inevitable “Wow. You must have some great parties, you know what I mean.” I do know what they mean and, sorry to say, they are likely to be sorely disappointed if they ever found out the truth about our parties (we just talk about weeds, the ‘boring’ ones). I do have a cheeky magnet from the city of Weed, California, on my filing cabinet, though.

[Biochica’s note: yeah… I’m going to need video footage of the next “Weed Science Society of America” conference. But I’ve got a nagging suspicion that it’s a “what happens at the conference, stays at the conference” kind of event *Wink, wink* ]

Q: Currently, there’s a lot of buzz surrounding “chemicals” in and on our food. Do you think that a world without herbicides is possible?

A: Is it possible? Sure. Don’t forget we farmed without synthetic, exogenous herbicides for millennia. And, despite what many might think, numerous weed scientists are looking at non-chemical strategies for weed control. For instance, in Georgia, we had a serious problem with glyphosate-resistant Palmer amaranth (Amaranthus palmeri). I worked with Dr. Stanley Culpepper (University of Georgia) to investigate the use of a fall tillage (soil inversion to a depth of 12 inches) coupled with a rye cover crop that we killed in the spring and used as a mulch to suppress Palmer seed germination/seedling emergence. Using  this strategy, we were able to reduce our in-crop Palmer amaranth densities by 90% or more. Now, we weren’t completely free of herbicides, but we did reduce the selective pressure that we put on them. As another example, Drs. Steve Fennimore and David Slaughter (University of California, Davis) are doing some really great work to develop automated weeding machines to use in high-value specialty crops (which have a limited number of herbicides available to them). However, with respect to your original question (Do you think that a world without herbicides is possible?), I’m going to have to say no… at least not at this time. We (weed scientists) are working with growers to diversify their weed production practices, but many do not have the money, the labor pool, the infrastructure, etc that will allow them to abandon herbicide use completely. Herbicides are a tool and our goal is to help growers use as many tools as are appropriate in their systems both safely and effectively.

[Biochica’s note: The Food Babe disagrees with you: no amount of chemicals is acceptable. Ever. Your nuanced explanation with references carries little weight when the Food Babe has spoken on the topic.]

Q: What are some of the more effective ways to get rid of weeds?

Lynn's picture of Bindweed

A: The answer to that question will depend on more than a few criteria, such as: what is the weed you are trying to get rid of, where is the weed located, and how hard do you want to work at getting rid of it, to name just a few. The most effective weed management strategies that might be employed in one’s backyard may be very different from those used by a commercial grower. For example, in a small patio space, hand-weeding is a viable strategy...the same is not true for thousands of acres of soybean. But all weed control strategies can be grouped into a few general categories: 1) exclusion or preventative measures (i.e. preventing weeds from entering your system), 2) physical disturbance (i.e. hand-weeding and cultivation), 3) obstruction (i.e. the use of a mulch or other time of barrier), 4) cultural practices (i.e. using crop rotation to manage weed populations), 5) biological control (i.e. allowing sheep to graze on edible weeds), and 6) chemical control (i.e. using a synthetic or organic herbicide to disturb plant growth and development). Ideally, we would encourage anyone/everyone to make use of as many strategies as are appropriate for their system. And, remember, you don’t have to figure this all out by yourself; your state extension personnel are there to help you with these kinds of decisions.

[Biochica’s note to the spouse: there are weed control strategies other than mulching!!]

Q:  Are there any new, more selective (and perhaps safer) herbicides in the pipeline?

A: I always tell my growers that they shouldn’t rely on the introduction of a new herbicide for weed control. We saw an abundance of products being released in the 1970’s and 1980’s, however the number of new discoveries has certainly plateaued. I don’t work for a chemical company, so I don’t know what the research pipelines look like, currently. If I had to speculate, I would suggest that the corporations are putting more money into crop trait development and big data. Assuming that we aren’t going to be getting a new herbicide product anytime soon, I think that we need to become smarter about how we use the ones that are available to us. For example, improved knowledge about weed biology and ecology will helps target weeds at the more vulnerable parts of their life cycles; in doing so, we will maximize the use of our herbicide tools and, hopefully, use them less frequently.

[Biochica’s note to Lynn: chemical companies should get into the astroturf business. Best weed-control system in California!!]

Q: Dr Andrew Kniss wrote an awesome post looking into that meme that I keep seeing on Facebook, about how vinegar+soap is “better” than Round-Up. He concludes that Vinegar+soap has a more toxic profile and is also more expensive. What often heard myth about weed science would you like to dispel if you could?

A: That we are only interested in applying herbicides. Yes, herbicides are useful tools, but weed scientists study/evaluate a wide range of management strategies. For example, I have worked, and still work with herbicides, but I have also been involved in other research projects looking at the effects of tillage, crop rotation, and cover crops on weed suppression and changes in weed community composition and structure. My colleagues at UC Davis and other institutions are engaged in many fascinating projects designed to further our understanding of weed biology and ecology, resistance evolution, and precision agriculture with respect to weed control.

[Biochica’s note to Lynn: my backyard is open to UC Davis plant community to study the impact of concrete and astroturf on weed development. I've actually had a few weeds make their way through!! I have created superweeds!!]

Q: You are stuck on an island and about to go insane from boredom. A genie suddenly appears and gives you the following choices (you have to pick one): a) an iPad with infinite battery life where your only App is Twitter and it's locked so you can only follow Nassim Taleb or b) A copy of "Seeds of Deception" by Jeffrey Smith. Which do you pick?

A: Taleb’s twitter feed. Although I disagree with his stance on GMOs, and often find him to be rude, there is interesting dialogue to be had.