Organic sweetpotato growers have limited effective weed management options, and most rely on in-season between-row cultivation and hand weeding, which are time consuming, are costly, and deteriorate soil quality. Studies were conducted at the Samuel G. Meigs Horticulture Research Farm, Lafayette, IN, and at the Southwest Purdue Agricultural Center, Vincennes, IN, in 2022 and 2023 to determine the effects of in-row plant spacing and cultivar selection on weed suppression and organic sweetpotato yield. The experiment was a split-split plot design, with in-row spacings of 20, 30, and 40 cm as the main plot factor, weeding frequency (critical weed-free period and weed-free) as the subplot factor, and sweetpotato cultivar (‘Covington’ and ‘Monaco’) as the sub-subplot factor. However, in 2022, we evaluated only in-row spacing and weeding frequency because of the poor establishment of ‘Monaco’. In 2023, sweetpotato canopy at 5 wk after transplanting (WAP) decreased as in-row spacing increased from 20 to 40 cm, and sweetpotato canopy cover of ‘Monaco’ (62%) was greater than that of ‘Covington’ (44%). In-row spacing did not affect weed density at 4, 5, and 6 WAP. As in-row spacing increased from 20 to 40 cm, total sweetpotato yield pooled across both locations in 2023 decreased from 30,223 to 21,209 kg ha−1 for ‘Covington’ and from 24,370 to 20,848 kg ha−1 for ‘Monaco’; however, jumbo yield increased for both cultivars. Findings from this study suggest that an in-row spacing of 20 cm may provide greater yield than the standard spacing of 30 cm for both ‘Monaco’ and ‘Covington’.

Sweetpotato [Ipomoea batatas (L.) Lam.] is a staple crop that provides nutritional benefits to humans globally, but it is subject to yield loss when competing with weeds, especially during the early stage of establishment. Yield loss can vary widely based on the cultivar, production environment, weed species, and management techniques. To address this challenge, we conducted field research at the Samuel G. Meigs Horticulture Research Farm, Lafayette, IN, and at the Southwest Purdue Agricultural Center, Vincennes, IN, in 2022 to determine the effect of sweetpotato cultivar on the critical weed-free period. The experiment was a split-plot design, with weed-free interval treatments as the main plot factor and cultivar as the subplot factor. The three cultivars used were ‘Covington’, ‘Monaco’, and ‘Murasaki’. Weeds were removed by hand and allowed to establish and compete with the crop beginning at 0, 14, 21, 28, 35, or 42 d after transplanting (DAP). As the weed-free interval increased from 0 to 42 DAP, predicted total yield increased from 19 kg ha−1 to 20,540 kg ha−1 for Covington, 3 kg ha−1 to 11,407 kg ha−1 for Monaco, and 125 kg ha−1 to 13,460 kg ha−1 for Murasaki at the Lafayette location. At Vincennes, as the weed-free interval increased from 0 to 42 DAP, predicted total yield increased from 14,664 kg ha−1 to 33,905 kg ha−1 for Covington, 4,817 kg ha−1 to 18,059 kg ha−1 for Monaco, and 12,735 kg ha−1 to 21,105 kg ha−1 for Murasaki. A threshold of ≤10% total yield reduction was achieved by maintaining sweetpotatoes weed-free 24 DAP for Covington, 20 DAP for Murasaki, and 33 DAP for Monaco.

Invasive emergent and floating macrophytes can have detrimental impacts on aquatic ecosystems. Management of these aquatic weeds frequently relies upon foliar application of aquatic herbicides. However, there is inherent variability of overspray (herbicide loss) for foliar applications into waters within and adjacent to the targeted treatment area. The spray retention (tracer dye captured) of four invasive broadleaf emergent species (water hyacinth, alligatorweed, creeping water primrose, and parrotfeather) and two emergent grass-like weeds (cattail and torpedograss) were evaluated. For all species, spray retention was simulated using foliar applications of rhodamine WT (RWT) dye as a herbicide surrogate under controlled mesocosm conditions. Spray retention of the broadleaf species was first evaluated using a CO2-pressurized spray chamber overtop dense vegetation growth or no plants (positive control) at a greenhouse (GH) scale. Broadleaf species and grass-like species were then evaluated in larger outdoor mesocosms (OM). These applications were made using a CO2-pressurized backpack sprayer. Evaluation metrics included species-wise canopy cover and height influence on in-water RWT concentration using image analysis and modeling techniques. Results indicated spray retention was greatest for water hyacinth (GH, 64.7 ± 7.4; OM, 76.1 ± 3.8). Spray retention values were similar among the three sprawling marginal species alligatorweed (GH, 37.5 ± 4.5; OM, 42 ± 5.7), creeping water primrose (GH, 54.9 ± 7.2; OM, 52.7 ± 5.7), and parrotfeather (GH, 48.2 ± 2.3; OM, 47.2 ± 3.5). Canopy cover and height were strongly correlated with spray retention for broadleaf species and less strongly correlated for grass-like species. Although torpedograss and cattail were similar in percent foliar coverage, they differed in percent spray retention (OM, 8.5± 2.3 and 28.9 ±4.1, respectively). The upright leaf architecture of the grass-like species likely influenced the lower spray retention values in comparison to the broadleaf species.

Injurious feather pecking in non-cage systems is a serious economic and welfare concern for the egg-producing industry. Here, we describe the first results from an ongoing collaborative project to improve range environment and welfare of laying hens (Gallus gallus domesticus) within the McDonald's Restaurants Ltd, UK supply base. The objective of this study was to investigate, in a commercial situation, the correlation between: i) proportion of range cover and ii) proportion of canopy cover, with plumage damage of end-of-lay hens. The assessment of plumage damage due to injurious feather pecking is a key animal-based welfare indicator for laying hens in non-cage systems. In 2007 and 2008, all laying-hen producers within the McDonald's Restaurants Ltd egg-supply base, were required to plant (if not present already), 5% of the total range area with blocks of trees ether side, and between 20-25 m from the laying hen house. Plumage damage at end of lay was positively correlated with mortality and flocks depleted in summer had less plumage damage at end of lay than flocks depleted in autumn or winter, possibly because of weather conditions at the time of placement. There was no correlation between the proportion (5-90%) of range cover and plumage damage at the end of lay, however, plumage damage was negatively correlated with percent of canopy cover within tree-planted areas. Providing a minimum of 5% tree cover, planted close to the house but with good canopy coverage, may be a feasible and practical method enabling producers to reduce plumage damage due to injurious feather pecking in their laying-hen flocks. Tree cover provision may also provide environmental benefits, such as soil stabilisation, reduced nutrient leaching and carbon sequestration.

Invasive alien species are a major threat to global biodiversity due to the tremendous ecological and economic damage they cause in forestry, agriculture, wetlands, and pastoral resources. Understanding the spatial pattern of invasive alien species and disentangling the biophysical drivers of invasion at the forest stand level is essential for managing forest ecosystems and the wider landscape. However, forest-level and species-specific information on Invasive Alien Plant Species (IAPS) abundance and their spatial extent are largely lacking. In this context, we analysed the cover of one of the world’s worst invasive plants, Chromolaena odorata, in Sal (Shorea robusta) forest in central Nepal. Vegetation was sampled in four community forests using 0.01 ha square quadrats, covering the forest edge to the interior. C. odorata cover, floral richness, tree density, forest canopy cover, shrub cover, tree basal area, and disturbances were measured in each plot. We also explored forest and IAPS management practices in community forests. C. odorata cover was negatively correlated with forest canopy cover, distance to the road, angle of slope, and shrub cover. Tree canopy cover had the largest effect on C. odorata cover. No pattern of C. odorata cover was seen along native species richness gradients. In conclusion, forest canopy cover is the overriding biotic covariate suppressing C. odorata cover in Sal forests.

We analysed thirty-five 400-m2 plots encompassing forest, savanna and intermediate vegetation types in an ecotonal area in Ghana, West Africa. Across all plots, fire frequency was over a period of 15 years relatively uniform (once in 2–4 years). Although woodlands were dominated by species typically associated with savanna-type formations, and with forest formations dominated by species usually associated with closed canopies, these associations were non-obligatory and with a discrete non-specialized species grouping also identified. Across all plots, crown area index, stem basal area and above-ground biomass were positively associated with higher soil exchangeable potassium and silt contents: this supporting recent suggestions of interplays between potassium and soil water storage potential as a significant influence on tropical vegetation structure. We also found an average NDVI cover increase of ~0.15% year−1 (1984–2011) with plots dominated by non-specialized species increasing more than those dominated by either forest- or savanna-affiliated species. Our results challenge the traditional view of a simple forest vs. savanna dichotomy controlled by fire, and with our newly identified third non-specialized species grouping also potentially important in understanding ecotonal responses to climate change.

Differential tree seedling recruitment across forest-savanna ecotones is poorly understood, but hypothesized to be influenced by vegetation cover and associated factors. In a 3-y-long field transplant experiment in the forest-savanna ecotone of Ghana, we assessed performance and root allocation of 864 seedlings for two forest (Khaya ivorensis and Terminalia superba) and two savanna (Khaya senegalensis and Terminalia macroptera) species in savanna woodland, closed-woodland and forest. Herbaceous vegetation biomass was significantly higher in savanna woodland (1.0 ± 0.4 kg m−2 vs 0.2 ± 0.1 kg m−2 in forest) and hence expected fire intensities, while some soil properties were improved in forest. Regardless, seedling survival declined significantly in the first-year dry-season for all species with huge declines for the forest species (50% vs 6% for Khaya and 16% vs 2% for Terminalia) by year 2. After 3 y, only savanna species survived in savanna woodland. However, best performance for savanna Khaya was in forest, but in savanna woodland for savanna Terminalia which also had the highest biomass fraction (0.8 ± 0.1 g g−1 vs 0.6 ± 0.1 g g−1 and 0.4 ± 0.1 g g−1) and starch concentration (27% ± 10% vs 15% ± 7% and 10% ± 4%) in roots relative to savanna and forest Khaya respectively. Our results demonstrate that tree cover variation has species-specific effects on tree seedling recruitment which is related to root storage functions.

A 4-yr field study was conducted near Grassrange, MT to determine the effects of single and repetitive picloram treatments for leafy spurge control in a native pasture. Single applications of picloram at 0.28, 0.56, 0.84, and 1.12 kg ae ha–1 averaged 0, 5, 22, and 61% leafy spurge shoot control 3 yr after treatment. Only the single applications of picloram at 1.68 and 2.24 kg ha–1 maintained leafy spurge control above 80%. A retreatment with 0.56 kg ha–1 picloram was required to maintain effective control for 3 yr when less than 1.68 kg ha–1 was applied. Leafy spurge canopy cover in the 1.68 and 2.24 kg ha–1 treatments averaged 14 and 6% 3 yr after treatment; however, all other single applications required retreatment.

Field experiments were conducted to select winter wheat (Triticum aestivum L.) cultivar(s) that were competitive to downy brome (Bromus tectorum L. # BROTE). Downy brome significantly reduced winter wheat grain yields of all cultivars by 9 to 21% at Lincoln, while at North Platte yield reduction ranged from 20 to 41% depending upon cultivar. ‘Turkey’ was the most competitive cultivar to downy brome but it had the lowest grain yield. Compared to ‘Centurk 78’, ‘Centura’ at Lincoln and ‘SD 75284’ at North Platte proved to be significantly higher yielding and more competitive to downy brome. Winter wheat tiller number, canopy diameter, and plant height were negatively correlated with downy brome yield, but changes in these growth parameters did not always translate into grain yield advantage in downy brome-infested plots. Based on stepwise regression analysis, wheat height was better correlated with reduction in downy brome yield than were canopy diameter or number of tillers.

Wooded meadows with a history of traditional land use over thousands of years support a great diversity of various taxa. Today, however, high-species-rich communities in wooded meadows are threatened because of the cessation of traditional management in large areas. We studied lichen communities on 136 deciduous trees (Betula spp., Fraxinus excelsior and Quercus robur) in 12 wooded meadows in three regions of Estonia, and assessed the effect of habitat change due to the abandonment of traditional management on epiphytic lichen species composition, considering factors on three spatial scales: regional, habitat and individual tree. The variation partitioning approach in partial Canonical Correspondence Analysis (pCCA) revealed that most of the variation in species composition is described by the species of host tree and tree bark pH. Other tree level variables, foremost tree diameter, described as much of the compositional variation as geographic location (region) or environmental conditions in wooded meadows. Of the environmental factors studied, woodland canopy cover is the strongest predictor of the change in epiphytic lichen species composition from the community type of semi-open wooded meadows to species-poor communities characteristic of secondary forest. General Linear Model (GLM) analysis of the abundance of the 35 most frequently observed lichen species revealed that more than half of them (21) are influenced by site openness (canopy cover and/or undergrowth density), showing that increasing canopy cover has a negative effect on the abundance of epiphytic lichen species characteristic of traditionally managed semi-open wooded meadows. The results emphasize that the preservation of large old deciduous trees of various species and the maintenance of the semi-open structure of stands are vitally important for the protection of epiphytic lichen communities in wooded meadows.

Environmental factors influencing grass establishment and performance in tropical savannas are poorly understood, particularly in relation to disturbance. We describe a seed sowing experiment that examined the effects of fire regime, canopy cover and litter cover on the emergence, establishment, height and fecundity (seed production) of the regionally dominant annual grass Sorghum intrans in northern Australia. Establishment was significantly lower under the woody canopy compared with canopy gaps, and where seeds were sown on a layer of litter compared with bare soil. However, variation in fire regime had no significant effect on establishment or seed production. Additionally, a shade-house experiment was conducted to test the effects of litter on seedling emergence of S. intrans and six other grass species representative of the local flora (Pseudopogonatherum contortum, Sorghum plumosum, Chrysopogon latifolius, Eriachne triseta, Heteropogon triticeus and Alloteropsis semialata). All species showed reduced emergence when sown either above or below litter, compared with bare soil. Our results demonstrate the importance of the overstorey as a determinant of S. intrans abundance and savanna grass composition more generally, through its effect on establishment. The aversion of savanna grasses to litter (and S. intrans to canopy shading) supports the notion of savanna species being highly adapted to disturbance.