Canada goldenrod (Solidago canadensis L.) is a serious invasive alien plant species that exerts negative effects on natural and agricultural ecosystems in China. Few studies have addressed the dispersal of S. canadensis to explain how it rapidly spreads to large areas over long distances. Here, we quantify the dispersal of S. canadensis via wind by capturing in situ−stained diaspores. The diaspores were trapped and counted along 11 radiating transects from the center of a dispersal source. Solidago canadensis diaspores could be dispersed in all directions from the source, traveling longer distances and in greater amounts in the downwind direction than the upwind one. With a source including about 58 million diaspores and a wind speed at Beaufort scale 4, the dispersal distance in the prevailing wind direction (PWD) was at least 2000 m. Diaspores shattered at a rate of approximately 3% daily with the common wind speed of scale 4, indicating that dispersal could last for more than a month. A mechanistic model was used to fit the dispersal curve along the PWD. Although the model slightly underestimated long−distance dispersal, it still demonstrated the potential of long−distance dispersal with great source strength. Wind−dispersed diaspores to new areas persisted over winter and were able to form new plants at a density of about 2 plants per m² at 500 m away from the source. Further experiments showed that the dispersed amount of S. canadensis diaspores was significantly positively correlated with the temperature and wind speed, but significantly negatively correlated with relative humidity, which indicated that, during a day, the maximum dispersal usually occurred in the afternoon when the temperature was the highest and the relative humidity the lowest. In addition, for an already existent population patch, the patch range can expand 2−4 m per year, mainly depending on the seedlings recruited from the rhizomes. These results provide insights into the long−distance dispersal of S. canadensis by wind and its effects on the range expansion process.

Shepherd’s-purse (Capsella bursa-pastoris), a globally distributed noxious weed species often found in wheat, has evolved resistance to ALS-inhibiting herbicides mainly due to single mutations in the ALS gene. In the present study, dose–response bioassays showed that a shepherd’s-purse population (R), collected from Xinghua, Jiangsu Province, China, had high level of resistance to the ALS-inhibiting herbicide, mesosulfuron-methyl (800-fold), and even much higher resistance levels to other reported ALS-inhibiting herbicides, tribenuron-methyl (1313-fold), bensulfuron-methyl (969-fold) and penoxsulam (613-fold). Sequencing of the open reading frame of the ALS gene revealed a double ALS gene mutation (Pro197-Ser plus Trp574-Leu) conferring the high resistance in the R plants. Docking analysis of the ALS protein and mesosulfuron-methyl predicts that the two amino acid substitutions in the R samples reduces the binding energy to the herbicide by decreasing the hydrogen bonds (H-bonds) and other interactions, thus endowing resistance to ALS-inhibiting herbicides. These results demonstrate that the double ALS mutation confers high resistance levels to ALS-inhibiting herbicides. To our knowledge, this is the first evidence of the double ALS mutation in shepherd’s-purse endowing ALS-inhibiting herbicide resistance.

Autopolyploidization has driven the successful invasion of Solidago canadensis in East Asia. However, it was believed that only diploid S. canadensis invaded Europe, whereas polyploids never did. Here, molecular identification, ploidy level, and morphological traits of ten S. canadensis populations collected in Europe were compared with previously identified S. canadensis populations from other continents and S. altissima populations. Furthermore, the ploidy-driven geographical differentiation pattern of S. canadensis in different continents was investigated. All ten European populations were identified as S. canadensis with five diploid and five hexaploid populations. Significant differences in morphological traits existed among diploids and polyploids (tetraploids and hexaploids), rather than between polyploids from different introduced ranges and between S. altissima and polyploidy S. canadensis. The invasive hexaploids and diploids had few differences in latitudinal distributions in Europe, which was similar to the native range but different from a distinct climate-niche differentiation in Asia. This may be attributed to the bigger difference in climate between Asia and Europe and North America. The morphological and molecular evidences proved the invasion of polyploid S. canadensis in Europe and suggest that S. altissima may be merged into a complex of S. canadensis species. Our study may be concluded that geographical and ecological niche differentiation of an invasive plant driven by ploidy depends on the degree of difference in the environmental factors between the introduced and native range, which provides new insight into the invasive mechanism.

Solidago canadensis L. is a regulated invasive alien species in China and was first recorded in the wild in Jiangsu Province. Despite widespread concern regarding its distribution and ecological associations, province-wide information on its current invasion status and associated plant community patterns in Jiangsu remains limited. To fill this gap, we conducted field surveys at 165 sites across Jiangsu Province and combined hierarchical clustering, plant-community diversity analysis, species-level analysis of accompanying-plant composition, redundancy analysis, and MaxEnt modeling to evaluate invasion-intensity patterns, associated environmental and anthropogenic factors, and plant-community responses in invaded communities. Solidago canadensis was recorded throughout the province, but invasion intensity was highest in southern Jiangsu. Hierarchical clustering classified the 165 sampling sites into three invasion-intensity groups. Group A (74 sites), concentrated in southern Jiangsu, was classified as the severe invasion group and showed generally lower plant diversity within the invaded-site dataset. Group B (60 sites) represented moderate invasion. Group C (31 sites), mainly distributed in northern and coastal Jiangsu, represented light invasion and retained relatively higher accompanying-plant diversity. Within S. canadensis-invaded communities, we documented 183 accompanying plant species from 43 families. Asteraceae and Poaceae were the most species-rich families, and annual or biennial herbs were the dominant life-form category. Species-level analysis further showed that accompanying-plant composition varied significantly along the invasion-intensity gradient (PERMANOVA, R² = 0.035), suggesting that differences in S. canadensis dominance were associated with detectable shifts in local plant assemblages. Redundancy analysis indicated latitude, transportation route density, and floating population density were closely associated with variation in S. canadensis invasion indicators and associated community variables, with soil pH, precipitation of the driest month, GDP, and motor vehicle ownership also contributing to the observed pattern. MaxEnt modeling identified southern and central Jiangsu as the main climatically suitable areas. This pattern was broadly consistent with the concentration of higher invasion intensity in southern Jiangsu. Nevertheless, field records in northern Jiangsu suggest that areas with lower predicted climatic suitability should also remain under continued monitoring. These findings suggest the need for coordinated management, particularly along major transportation corridors and in highly disturbed urban habitats. Control efforts should combine zoning management, source control, repeated removal, and habitat restoration tailored to local conditions.

Solidago canadensis is one of the most destructive invasive plants in China, and current physical and chemical control methods are often costly, inefficient, and ecologically risky, highlighting the urgent demand for green and efficient ecological alternatives. The native vine Humulus scandens exhibits strong allelopathic potential. In this study, allelochemicals from its leaves and stems were extracted using petroleum ether, ethyl acetate, n-butanol, and n-hexane. Their allelopathic effects on S. canadensis were systematically evaluated through seed germination, seedling growth, and rhizome propagation assays, combined with widely targeted metabolomics. Leaf extracts showed markedly stronger allelopathic inhibition than stem extracts. Among all fractions, the ethyl acetate extract exerted the most potent suppression on seed germination, significantly reducing germination rate and root elongation in a concentration-dependent manner. At 100 g·L⁻¹, leaf extracts—especially the ethyl acetate phase—significantly decreased belowground fresh weight, rhizome number, and new seedling emergence. The ethyl acetate extract also significantly elevated root antioxidant enzyme activities at 25–100 g·L⁻¹, indicating induced oxidative stress. UPLC-MS/MS-based metabolomics identified 186 differential metabolites among extracts. Ten flavonoids were significantly upregulated in the ethyl acetate extract and were predominantly enriched in the kaempferol aglycone biosynthesis I pathway (MetMap 113) and the flavonoid biosynthesis pathway (ko00941), suggesting that these compounds may play a key role in the observed allelopathic inhibition. Collectively, the ethyl acetate extract of H. scandens leaves effectively suppresses S. canadensis growth by inhibiting seed germination and rhizome tillering and by inducing oxidative stress, probably with the 10 candidate flavonoid metabolites, highlighting its strong potential as a biological control agent against this invasive weed.

Mechanized agriculture has created important pathways for weed seed dispersal; yet, the influence of seed morphological and phenological traits on harvester-mediated dispersal remains poorly understood. Field surveys and simulated dispersal experiments were conducted to investigate the factors affecting weed seed dispersal in rice–wheat cropping systems. Field investigations across 60 fields identified 54 weed species retained on combine harvesters after rice and wheat harvesting, with Poaceae species dominating the retained seed assemblage. Seed retention was strongly associated with plant height, seed size, appendage type, and phenological synchrony with crops. Species with a tall stature, large seeds, and synchronized maturity were disproportionately retained by harvesters. Cluster analysis classified weed species into four mechanical dispersal types according to their dispersal potential. Simulated dispersal experiments demonstrated that seed deposition followed an exponential decay pattern with increasing harvesting distance. Seeds possessing rough surfaces or appendages showed lower attenuation coefficients and longer dispersal distances than smooth seeds. Harvester-mediated dispersal distances exceeded 2 km during continuous field operation. These findings demonstrate that combine harvesters act not only as dispersal vectors but also as selective filters favoring weed species with specific trait combinations. Integrating harvest weed seed control technologies with machinery hygiene practices will therefore be essential for sustainable weed management.