Imagine a weed that can produce 600,000 seeds per plant and grow as much as 2.5 inches per day. Such a weed exists, and it’s not being grown somewhere in a secure lab — it’s widespread in the fields of Alabama farmers and throughout the United States.
This “super” weed — Palmer amaranth — is considered the most difficult weed to control, with weeds being the No. 1 overall threat to crop production. So, it’s the worst of the worst.
Weeds like Palmer amaranth and Italian ryegrass can quickly evolve resistance to many important herbicides and have the potential to transfer that resistance to new plants through pollen movement.
“Among the major biotic constraints, weeds are considered as the most harmful to agricultural production in addition to affecting agrobiodiversity and natural water bodies,” said Aniruddha Maity, assistant professor in the College of Agriculture’s Department of Crop, Soil and Environmental Sciences.
Maity is the leader of the Weed Bionomics Laboratory, which focuses on, among other things, managing herbicide-resistant weeds like Palmer amaranth and Italian ryegrass.
“The Weed Bionomics Lab focuses on the biology, ecology and integrated management of weeds and invasive plant species in managed and natural ecosystems, which advances current understanding of plant species that are designated as weed species,” Maity said.
Relying on inter-disciplinary and collaborative approaches, the lab’s research includes a basic component that increases the fundamental knowledge on the evolution and ecological importance of weed species. It also has an applied component that addresses the practical issues of weed infestation across cropping systems.
“In the current scenario of rapid evolution and spread of herbicide resistance in major weeds, potential areas of research include, but are not limited to understanding influences of various biotic and abiotic factors on weed adaptation, weed dispersal mechanisms, soil seedbank dynamics and statewide herbicide resistance surveys,” Maity said.
“We are also developing novel and creative herbicidal and non-herbicide-based weed management concepts and practices that take advantage of an improved understanding of management impacts on the biology of dominant weed species,” he added.
Additionally, researchers in the lab are working to understand soil-herbicide-weed interactions in the presence of cover crops, poultry litter and biochar across soil types. They also are looking at the extraction of bioherbicides from native weed and invasive species and weed detection and management using drone and machine-learning approaches.
But herbicide-resistant weeds are a focal point of the lab, and for good reason, Maity said.
“Since the commercialization of synthetic herbicides and thereafter the introduction of no or reduced tillage for crop management, herbicides have been used as the primary tool weed management across the globe, even more so in the Western countries,” he said.
The repeated use of selected herbicide chemistries has led to the selection of herbicide-resistant individuals in the weed populations across species and regions.
Besides other factors, phenotypic plasticity — defined as the ability of plants to change their phenotype to accommodate environmental changes — has led to the development of 534 unique reported cases of herbicide resistant weeds covering 273 species in 101 crops across 75 countries.
There is no silver bullet to contain the evolution and spread of herbicide resistance in weeds, Maity said.
“Rotating crop and alternating herbicide chemistries, in addition to using non-herbicidal tools such as weed-free crop seed, weed-suppressant crop cultivars, ecological approaches, effective water and nutrient management, and the use of cover crops all should be incorporated into weed management programs,” he said.
Selected research projects being undertaken by the lab and the sponsoring agency or organization include the following:
- Understanding the influences of endophytes and abiotic factors on herbicide resistance development in Italian ryegrass: AFRI, USDA-NIFA.
- Climate-smart cotton: developing precision regenerative practices and market opportunities for addressing climate change in the Cotton Belt: USDA-SAS.
- Use of biochar in agricultural systems: USDA-ARS.
- Integrated weed management, resistance monitoring and weed distribution in Alabama: Cotton Inc.
- Herbicide resistance survey and developing management strategies for tropical spiderwort and goosegrass in Alabama peanut fields: National Peanut Board.
- Statewide survey of water hemp and horseweed populations for herbicide resistance screening: Alabama Cotton Commission.
- Mapping and estimating early and late-season cotton weeds using drone imagery for their precision management. Alabama Cotton Commission.
“The work done by Dr. Maity not only provides information on how weeds evolve under different agricultural practices and climates but also helps growers to minimize the cost of weed management,” said Sushil Biosystems, professor, Biosystems Engineering; interim associate dean for research, College of Agriculture; and interim associate director of the Alabama Agricultural Experiment Station.
The Weed Bionomics Laboratory also is reaching into Auburn’s past, that is registered on the National Register of Historic Places, to help develop strategies for future weed control. Established in 1911, the Cullars Rotation is the oldest continuous soil fertility experiment study in the South and is located near the main campus.
“The Cullars Rotation holds immense importance when we talk about long-term nutrient management impacts on weed seedbanks and overall weed recurrence,” Maity said. “In a current trial, one of our researchers is studying the status of weed seedbank reservoirs and seasonal weed emergence.”
Researchers in the Weed Bionomics Laboratory, in addition to Maity, include Akashdeep Singh, Andrew Ahlersmeyer, Mahboobeh Mollaee, Nisith Nishank Purohit, Rakesh Kumar Ghosh, Ravneet Kaur and Wilfried Kayaba Ouedraogo.
