The genetic basis of weedy and invasive traits and their evolution remain poorly understood, but genomic approaches offer tremendous promise for elucidating these important features of weed biology. However, the genomic tools and resources available for weed research are currently meager compared with those available for many crops. Because genomic methodologies are becoming increasingly accessible and less expensive, the time is ripe for weed scientists to incorporate these methods into their research programs. One example is next-generation sequencing technology, which has the advantage of enhancing the sequencing output from the transcriptome of a weedy plant at a reduced cost. Successful implementation of these approaches will require collaborative efforts that focus resources on common goals and bring together expertise in weed science, molecular biology, plant physiology, and bioinformatics. We outline how these large-scale genomic programs can aid both our understanding of the biology of weedy and invasive plants and our success at managing these species in agriculture. The judicious selection of species for developing weed genomics programs is needed, and we offer up choices, but noArabidopsis-like model species exists in the world of weeds. We outline the roadmap for creating a powerful synergy of weed science and genomics, given well-placed effort and resources.

Summary 1.Gene flow from transgenic crops to feral populations and naturalized compatible relatives has been raised as one of the main issues for the deregulation of transgenic events. Creeping bentgrass, Agrostis stolonifera L., is a perennial, outcrossing grass that propagates by seeds and stolons. Transgenic Roundup Ready® glyphosate-resistant creeping bentgrass (GRCB), which is currently under USDA-APHIS regulated status, was planted in 2002 on 162 ha within a production control area in Oregon, USA. 2. We conducted a study to assess transgene flow from the GRCB fields. A survey within and around the production control area was performed during the year when the GRCB fields produced seed and for 3 years after the fields were taken out of production. Transgene flow was determined by testing creeping bentgrass and its relatives for expression of the glyphosate resistance transgene. 3. While GRCB seed-production practices were strictly regulated, evidence of transgene flow was found in all years. In 2006, 3 years after the transgene source fields were taken out of production and a mitigation programme was initiated, 62% of the 585 creeping bentgrass plants tested in situ were glyphosate-resistant (GR). Our results document not only the movement of the glyphosate resistance transgene from the fields, but also the establishment and persistence of high frequencies of GR plants in the area, confirming that it was unrealistic to think that containment or eradication of GRCB could be accomplished. 4. Synthesis and applications : These findings highlight the potential for transgene escape and gene flow at a landscape level. The survey provides empirical frequencies that can be used to design monitoring and management methods for genetically engineered (GE) varieties of outcrossing, wind-pollinated, perennial grasses and to evaluate the potential for coexistence of GE and non-GE grass seed crops. Such information should also be used in the decision-making process for authorization of field trials and deregulation of genetic engineering events.

Gene flow from transgenic glyphosate-resistant crops can result in the adventitious presence of the transgene, which may negatively impact markets. Gene flow can also produce glyphosate-resistant plants that may interfere with weed management systems. The objective of this article is to review the gene flow literature as it pertains to glyphosate-resistant crops. Gene flow is a natural phenomenon not unique to transgenic crops and can occur via pollen, seed and, in some cases, vegetative propagules. Gene flow via pollen can occur in all crops, even those that are considered to be self-pollinated, because all have low levels of outcrossing. Gene flow via seed or vegetative propagules occurs when they are moved naturally or by humans during crop production and commercialization. There are many factors that influence gene flow; therefore, it is difficult to prevent or predict. Gene flow via pollen and seed from glyphosate-resistant canola and creeping bentgrass fields has been documented. The adventitious presence of the transgene responsible for glyphosate resistance has been found in commercial seed lots of canola, corn and soybeans. In general, the glyphosate-resistant trait is not considered to provide an ecological advantage. However, regulators should consider the examples of gene flow from glyphosate-resistant crops when formulating rules for the release of crops with traits that could negatively impact the environment or human health.

Open‐field burning, an effective and economical practice for increasing seed yield in creeping red fescue (Festuca rubra L.), has been restricted in Oregon due to air quality and safety issues. The use of the plant growth regulator trinexapac‐ethyl [4‐(cyclopropyl‐α‐hydroxy methylene)‐3,5‐dioxocyclohexane carboxylic acid ethyl ester] (TE) was evaluated as a potential alternative to open‐field burning for maximizing yield in creeping red fescue over 4 yr. Fall and spring applications of TE in combination with residue management practices, open‐field burning and mechanical removal (flailing) of post‐harvest residue, were evaluated to determine potential effects on seed yield and dry matter partitioning. Spring TE applications in burn plots increased cumulative seed yield by 38% over the check. In flail plots, spring TE applications increased yield by 30 and 16% over the burn check for the first 2 yr, but no response was observed later. Open‐field burning was critical for maintaining high yields in the last 2 yr. Although late‐spring TE applications in flail plots resulted in cumulative yields comparable to those of burn check plots, yields were 34% lower than those of burn, TE spring‐treated plots. Fall TE applications had no consistent effect on seed yield. Therefore, neither spring nor fall TE applications are an effective alternative to replace open‐field burning in creeping red fescue seed production over the life of the stand if seed yield is to be maximized. Spring TE applications plus open‐field burning maximized seed yield and had the greatest harvest index, resulting in a more efficient crop.