Area Weed Science Research
NORTHEAST
Tree of Heaven (TOH), Ailanthus altissima, an invasive species introduced into the US in the late 1700s, is now present in many regions. The invasive tree species thrives in disturbed areas with poor soil, grows clonally, and produces large numbers of seed for further spread. Unfortunately, TOH also support survivorship and development of a recently introduced invasive planthopper, spotted lanternfly (SLF), Lycorma delicatula. SLF first arrived in eastern Pennsylvania in 2014 and has since spread to 16 additional states throughout the eastern half of the US. This invasive insect prefers TOH as a feeding host season-long, is more fecund when TOH is part of their diet, and is often present in extremely high densities on trunks that lead to a large pest reservoir in unmanaged habitats. Unfortunately, SLF will disperse from TOH, especially when trees become less acceptable due to intense feeding leading to reduced tree vigor, to feed on other hosts including wine grapes. SLF dispersal into vineyards has resulted in increased insecticide inputs, reduced yields, and increased winter injury. A team of ARS scientists at Kearneysville, WV and university collaborators are developing biological control agents for SLF and TOH to suppress populations of both invasive species to increase ecosystem health, mitigate yield losses, and alleviate impacts on native pollinators and plant species.
MIDWEST
The impact of climate change on vegetable crops, which are more sensitive to environmental stressors than staple cereal crops and are essential to human health, has received little study. ARS researchers in Urbana, Illinois, used a sweet corn dataset collected on 16,040 fields across a 27-year period to unravel the significance of local weather anomalies on sweet corn yield. High temperatures (>86 degrees F) during flowering resulted in significant yield losses in sweet corn which were exacerbated under rainfed conditions. This result is cause for concern given predictions of increased frequency of hotter and drier mid-season growing conditions in much of the U.S. Corn Belt. The research underscores the critical importance of prioritizing crop adaptation strategies to high temperature to sustain production of this very popular crop.
PLAINS
Flowering rush is a highly invasive aquatic weed affecting waterbodies and waterways across North America. ARS researchers at Sidney, Montana, are leading the first North American quarantine rearing program, in collaboration with Agriculture and Agri-Food Canada and the Centre for Agriculture and Bioscience International, for Bagous nodulosus, a new candidate biological control agent recently permitted for field release in Canada. Initial colony establishment has been successful, and a first generation of lab-reared insects has been shared with Canadian colleagues to develop additional rearing and research populations in anticipation of release programs. If permitted for release in the U.S., these agents have the potential to reduce the cover and abundance of flowering rush infestations and enhance water, irrigation, and recreation resources.
PACIFIC WEST
New technology provides the ability to forecast short-term, site-specific weather conditions to predict forage production. Climate and weather directly affect plant production across rangeland ecosystems. Forecasting rangeland plant production could provide valuable management information pertaining to livestock purchasing decisions, restoration planning, wildfire fuel loads, and wildlife management decisions. ARS researchers in Burns, Oregon, and Boise, Idaho, developed plant production models using climate data that reliably identify key plant group production responses to weather inputs across time and space. These climate forecasts and plant production models produce significant plant production forecasts with lead times of up to seven months. The ability to predict production using short-term weather forecasts is in the early stages of adoption by federal and state land management agencies and ultimately will be useful to private livestock producers and conservationists interested in better managing rangeland landscapes.
SOUTHEAST
The triketone class of herbicides plays an important role in controlling weeds, especially in crops such as corn, soybean and wheat. The main herbicides in this class are mesotrione and sulcotrione which are analogs of the allelochemical leptospermone from the bottlebrush plant. However, the degradation products of mesotrione and sulcotrione can negatively affect aquatic plants and microorganisms. The benzoic rings resulting from the degradation of these herbicides are responsible for the toxic effects. To develop more environmentally friendly triketone herbicides, ARS researchers in Oxford, Mississippi, made a series of structurally related triketone analogs originating from malonic acid, a naturally occurring compound found in many fruits and vegetables. Bioassay results indicated that these newly synthesized compounds exhibited strong herbicidal activity. Unlike mesotrione and sulcotrione, these compounds lack benzoic rings. The new chemical entities (keto-diesters) provide a new class of herbicides and their mode of action is likely similar to that of mesotrione and sulcotrione. In addition, several keto diether-based compounds developed were found to reduce potential leaching in plant leaves compared to commercial triketone herbicides. A patent is being filed and should allow for commercial production for use by growers and producers in a wide range of cropping systems.
