Research Spotlight

DR. MARTY WILLIAMS 

The WSN reached out to Marty to get his thoughts on weather extremes, weed dynamics, and herbicide resistance to name a few and his advice to those thinking about a career in weed science. Marty is a weed ecologist at the ARS Global Change and Photosynthesis Research Unit in Urbana, IL.

WSN: Hi Marty. How are you? Enjoying the weather so far?

Marty: What a crazy start to a field season. Some of the first field experiments we planted this spring were flooded out. And every time field conditions almost became suitable, it rained again. It has been eerily representative of Brad Tomasek's MSc thesis chapter on projected changes in field workability for Illinois that we published in 2017. We have since caught up on planting field experiments.  Interestingly in the same paper cited above, we discovered summer drought metrics were expected to increase under every greenhouse gas emissions scenario.  So, for now, we're hoping the rains return in moderation.  Time will tell. 

WSN: That does sound wild. Not really tracking the 30-year average that we’ve been using for decades. Are you seeing more 100-year events in terms of drought and if so, how are growers coping in the Midwest?

Marty: I believe the latest climate assessment for Illinois was published in 2021.  In that report, Illinois has gotten warmer and wetter.  Warming has been driven more by nighttime temps than daytime temps, which is most noticeable in the summer.  Changes in precipitation vary seasonally, with greater winter and spring precipitation, and less summer precipitation.  Interestingly, intense rainfall events (>2") occur more often.  Based on changes in both temp and precipitation, risk of short-term droughts is expected to increase.  For sure, weather is at the top of growers' minds.  Illinois has some fantastic soils for rainfed crop production, but they're not immune to the challenges of farming in a changing climate.  Many fields are tiled, or being retiled, which can help with intense rainfall events.  We've seen a trend in earlier plantings - when possible - especially for soybean.  We're also seeing changes in specialty crop production.  Warming temperatures are shifting plant hardiness zones northwards.  At the same time, certain crops are becoming more difficult to grow.  For instance, commercial sweet corn production in the state has plummeted in recent years.  Perhaps no surprise, as Daljeet Dhaliwal's PhD work found just how risky it is to grow sweet corn under rainfed conditions in the Midwest.  So perhaps 'coping' for some is as profound as not growing certain - even long-established - crops.

WSN: So, what about weeds? Since you’ve been in the Midwest, what changes have you seen in terms of species and their impacts? Have some faded and others taken their place? Which ones have moved in?

Marty: I share your interest in the trajectories of individual weed species over time.  I find enjoyment in finding older literature on the problem weeds of yesteryear, and whether they remain a problem today or not.  It seems common lambsquarters has been around and problematic for over a century.  Wild buckwheat was among the most problematic weeds in major vegetable crops of the Midwest in the 1960's; however, it didn't show up in our multiple surveys of Midwestern fields since the 2000s.  Most of your readers are familiar with waterhemp.  It appears to have become a problem beginning in the 1990s and is now a poster child of multiple herbicide resistance.  Such trends make me wonder about the adaptations that have occurred in species that now thrive.  And not just herbicide resistance, but other traits as well.  What genetically inherited traits have played an important role in their success?  Moreover, can we use such knowledge to improve how we manage the weeds?  For traits related to stress tolerance (i.e. flooding, drought, heat, etc.), can we use such knowledge to help our crops adapt to climate change?  With recent advances in weed genomics as well as other tools in population genetics, bioinformatics, machine learning, and more, there are some exciting new and important opportunities for those who study weeds.   

WSN: Wow! You’ve really spanned the ages to over 60 years ago and topics to our modern molecular approaches. I know you spent some time earlier in your career in eastern Washington. What have you noticed through your research that is different about weeds there compared to where you are now in Illinois? What about how growers approach them in terms of management – any social differences, as well?

Marty: Haha! Let me be clear, I haven't been studying weeds for 60 years! In comparing the inland Northwest to the Midwest, the first thing that jumps out to me is that it is easier to do field research on irrigated crops in the Northwest. Being able to control water supply is hugely helpful. Timing of field events was very predictable. While the Northwest is still at the mercy of mother nature (e.g. winter snowpack to keep the irrigation flowing in the summer), the Midwest weather throws a direct punch, and often. The diversity of weed problems in the Northwest is more striking, too. The orographic effects create a wide range of environmental conditions over relatively short distances. Crop diversity is large, therefore crop and weed management tactics are all over the board. This diverse landscape results in a host of complex weed issues not just in cropping systems but also in aquatic environments, forests, riparian areas, and rangelands. For many growers, herbicides are the first line of defense against weeds.  My sense, and I have no data to support this, is that growers in the Northwest are more amenable to diversified weed management compared to the Midwest. This is born out of necessity. Many crops grown in the Northwest have fewer registered herbicides compared to corn and soybean of the Midwest. Genetically modified herbicide tolerant crops are the exception, not the norm.  Crop rotations further restrict herbicide use. Weeds are no less of a problem in the Northwest, so it makes sense that if one has limited herbicide options, they would think and act 'outside the box' for solutions to persistent weed problems.

WSN: Hey, not a lot of people have been doing research on weeds for 60 years, so no misunderstanding there! It’s just that we as a collective see so much change, but we seldom take time to reflect on it as you did. Speaking of change, you talked about grower approaches across regions, and it would be interesting to hear your take on the effects of the Endangered Species Act and what it’s going to do to herbicide use and how growers might have to change their approach.

Marty: I know that EPA's action on ESA is on the minds of many.  It certainly sounds like significant changes in herbicide use are possible.  While the details of these changes remain to be seen, it's not hard to envision a potential collision course for specific products.  ESA isn't about a cost-benefit analysis.  Critical habitat of endangered species can't be compromised by the actions of federal agencies, such as EPA's registration of herbicides.  Consider dicamba in recent years.  Following the launch of dicamba-tolerant soybean, off-target injury complaints have marred the technology.  It's one thing to frame dicamba vapor drift as applicator error or a relatively minor problem for non-DT soybean, but it's quite another issue if you consider the landscape as a whole, which sometimes contains endangered species.  While the days of over-the-top dicamba applications in DT soybean are numbered, the issue illustrates the scope that EPA must now act.

WSN: Great points. Another issue is the cost of implementing practices to meet the proposed ESA standards and how are growers and practitioners going to pay for them. The good thing is that EPA is engaging in what appears to be an open and transparent discussion to find an agreeable solution. Time will tell. Do you ever see a period in the future when herbicide resistance will not be an issue?

Marty: I try to be a glass half-full kind of guy, but I don't see HR going away in my lifetime.  That being said, HR also reflects the power of natural selection in plants.  Pretty impressive.

WSN: You’re probably right, although these new robots that keep coming out are pretty impressive, as well, in what they can do and their selectivity. It’s been really great visiting with you. Before we finish, do you have any advice for the those in weed science or are considering it as a possible career?

Marty: I agree, there are exciting developments in physical weed control technology.  I look forward to seeing the tools that gain traction for the long haul.  Advice?  Go for it.  There is a confluence of factors that make for an exciting and challenging time in weed science.  Perhaps the stakes have never been higher.  Wherever your passion lies - research, development, teaching, or other - if you want to help solve important problems, we need you.  

WSN: Well said. Thanks, Marty.