Weed Seeds Research Articles

Replacing methyl bromide with a combination of 1,3-dichloropropene and metam sodium for cucumber production in China.

The combination of 1,3-dichloropropene (1,3-D) and metam sodium (MNa) is a potential resource to replace methyl bromide (MB) as a soil fumigant. The efficacy of 1,3-D+MNa as a crucial factor to limit soil-borne pests was evaluated in one laboratory experiment and two cucumber greenhouse studies conducted in commercial operations. Laboratory results revealed that 1,3-D and MNa (10+20 mg a.i. kg−1 soil) provided the best complementary control of the root-knot nematode, Fusarium oxysporum and two species of weed seeds. Greenhouse trials revealed that the blend of 1,3-D and MNa (10+20 g a.i. m−2) greatly inhibited the ability of Meloidogyne incognita to form root galls. In addition, the number of colony-forming units of F. oxysporum declined substantially after growth on media, resulting in higher fruit yields and greater economic benefits. The combined use of 1,3-D and MNa exhibited a higher control efficacy than when 1,3-D or MNa was utilized alone. The ability of this chemical combination to control soil-borne organisms did not differ significantly from the MB treatment and maintained high cucumber yields, enhancing the income of the farmers. Compared to the untreated control group, all the chemical treatments prominently improved the control of the pests. These results show that applying a combination of 1,3-D and MNa provides a promising alternative to MB that enables the sustained growth of cucumber production in China.

Seed Dormancy and Seed Morphology Related to Weed Susceptibility to Biofumigation

Biofumigation is practiced to control soilborne pests and weeds in agronomic fields. The objectives of this research were to assess the dose response of weed seeds to Indian mustard biofumigation and associate responses to seed dormancy state, initial dormancy, and seed parameters. A petri dish biofumigation methodology was developed to expose seeds of common lambsquarters, bird vetch, wild carrot, common ragweed, green foxtail, velvetleaf, hairy galinsoga, and red clover to allelochemicals produced after rehydrating 0 (control), 1.94, 2.90, 5.81, 11.61, and 17.41 mg cm−2of dried mustard powder. Weed species expressed specific dose responses, estimated ED50, LD50, and maximal mortality. Hairy galinsoga and wild carrot were consistently the most affected by biofumigation, with maximal mortality reaching 97% and 95%, ED50values for germination were 1.91 and 2.68 mg cm−2, and LD50values were 3.31 and 3.69 mg cm−2of dried mustard tissue, respectively. Initial dormancy was assessed by germination and tetrazolium tests. Seed parameters such as testa thickness, relative weight of the testa, and seed size were measured directly by manual dissection, weighing seed structures, and stereomicroscopic imaging software measurements. Linear regression analyses revealed initial dormancy to be positively related to ED50and LD50values with a significant interaction with seed surface and seed width, respectively. Exposure to 5.81 mg cm−2of dried mustard powder increased common ragweed seed mortality for after-ripened seeds by 293% and by 58% for primary dormant seeds compared with untreated seeds. Mortality of common lambsquarters secondary and primary dormant seeds increased by 730% and 106%, respectively, and for wild carrot by 1,193 and 156%, respectively. Results underline the potential to incorporate biofumigation into weed management programs for repression of susceptible weed species.

Weed Seed Inhibition under Solarization Treatment with Different Mulch Color in Tropical Highland Organic Farming System

Weeds are the major problem in organic crop production. Soil solarization is a method using clear plastic films to increase soil temperature to control pest organisms such as fungi, bacteria, and weed seeds. The study aimed to evaluate the effect of different plastic mulch color on weed seed inhibition. The experiment was carried out in CAPS Research Station located in Air Duku Village, Bengkulu, Indonesia at 1054 m above sea level, arranged in Randomized Completely Block Design with 3 replications. Treatments comprised 4 different colors of plastic films, i.e silver-black, black, clear, and red as well as control (without mulch). Plastic mulch was laid on 1 m wide x 2 m long raised soil bed for four weeks from April 20–May 23, 2016. Soil temperature underneath plastic mulch at depth of 5, 10, 15, 20 cm from the surface were measured daily at noon. After incubation, soil sample was collected from 0-5; 5-10; 10-15; 15-20 cm depths. Weed seed germination of each soil sample was tested in the greenhouse. A number of weeds were observed after four weeks. The experiment indicated that a month of soil solarization using clear plastic mulch resulted in greatest soil temperature, increasing by 0.54-1.84% as compared to control. Treatment of plastic mulches was effective to suppress seed inhibition at the soil depth of 0-15 cm, as indicated by numbers of germinated weed and its dry matter. Longer soil solarization is necessary to obtain the highest reduction of weed growth in tropical highland organic farming system.

A new approach to soil solarization: Addition of biochar to the effect of soil temperature and quality and yield parameters of lettuce (Lactuca Sativa L. Duna)

Abstract Soil solarization is a non-chemical method used to destroy soil borne pathogenic, harmful, and weed seeds in agricultural field and greenhouses. Solarization is generally applied in regions with high summer air temperatures and high solar radiation. Organic materials obtained as a result of the pyrolysis process in an anaerobic environment is called biochar. It can be produced from a wide range of plant and animal origin biomass sources. Lettuce plants are an important vegetable species grown after the application of solarization because of their high value and compatibility with autumn growing. Researchers reported that lettuce yields increased following soil solarization. The aims of this work were to examine different mulch materials and addition of biochar (a new approach in soil solarization) of soil temperature change, and determine which month is more effective according to temperature difference, and also effect of solarization application on yield, quality, and leaf nutrient content characteristics of lettuce plant. The experimental site was located at the University of Suleyman Demirel University in Isparta and the study was conducted during summer and autumn of 2016. Two different polyethylene (PE) mulch materials have been tested. Four different treatments and non-solarization were performed in this research. There were PE mulch, bubble PE mulch, PE + biochar, bubble PE+ biochar and non-solarization treatments. In the parcels where biochar application is used, it was applied 150 g m −2 of the soil surface as a thin mulch. Biochar added bubble solarization mulching film was determined to be more effective with regard to temperature increase and heat conservation in comparison with the traditional mulch material. Solar radiation played an important role in rising soil temperature with mulch material. With the fall of solar radiation in August, temperatures under mulching films decreased. But, temperature inside the greenhouse and the temperature of the bare soil did not change or it was affected less. Yield increase of 100% was attained for lettuce yield increase with biochar added bubble solarization mulch in comparison with the control. Thus, the study reached the determined objective and it has been determined that biochar use plays an important role in the effectiveness of solarization applications.

Ecosystem services and disservices provided by small rodents in arable fields: Effects of local and landscape management

Abstract In agriculture, both valuable ecosystem services and unwanted ecosystem disservices can be produced by the same organism group. For example, small rodents can provide biological control through weed seed consumption but may also act as pests, causing crop damage. We studied the hypothesized causal relationships between ecosystem services (removal of weed seeds) and disservices (removal of wheat grains and crop damage) derived by small rodents (voles and mice) at multiple spatial scales. At the landscape scale, we studied the effects of landscape compositional and configurational heterogeneity on the abundance of voles and mice and their related ecosystem services and disservices along the former inner German border in east and west Germany. At the local scale, we studied how abundance and ecosystem functions are affected by management intensity (organic vs. conventional winter wheat), associated differences in crop characteristics and edge effects. Linear mixed‐effects models and path analysis show that voles drove ecosystem disservices, but not ecosystem services, in agricultural fields. Daily wheat seed removal by voles was influenced by increasing wheat height and was almost three times higher than weed seed removal, which was not related to local‐ or landscape‐scale effects. Abundance of voles and associated crop damage decreased with lower crop density and higher wheat height, which were associated with organic farming. Abundance of voles and crop damage were highest in conventional fields in west Germany. Synthesis and applications. As the ecosystem disservice of wheat seed consumption by small rodents must be considered mainly during crop sowing, management before crop harvest should focus on decreasing the pest potential of voles but not mice. Our results suggest that densities of voles and their ecosystem disservices could be reduced by having fields with low crop density and high wheat height, practices associated with organic farming. Surrounding landscapes with low compositional and configurational heterogeneity could further reduce voles’ pest potential, but with probable negative effects on farmland biodiversity.

Bagged Commercial Soils are an Avenue for Regional Dispersal of Weedy Plant Species

Abstract The spread of weedy plant species is a constant and increasing problem in the United States. A number of weed seed dispersal mechanisms are recognized, but one that may not have received attention is the potential for movement via the production and distribution of bagged soils for commercial sale. Our objective was to test the most common and inexpensive soils available at gardening supply stores in South Carolina for the presence of weeds. We identified 80 species or genera from 20 families in 19 different soil products. Most of the species were ubiquitous and many are restricted to the southern states, but some species are locally uncommon. We suggest the movement of different genotypes, even of common weeds, may create new evolutionary potential that could have long-term consequences for local adaptation of these species. The constant influx of weed seeds also creates propagule pressure and could contribute to further spread. We recommend commercial soil producers and distributors take steps ...

Soil weed seedbank dynamic and allelopathic potential of <i>Tithonia diversifolia</i> (Hemsl)

The phenomenon of allelopathy is receiving increased attention as a possible alternative weed control method that is environment-friendly when compared with the use of herbicides with a wide range of toxic side effects which pose potential hazards to the environment. This study was designed to estimate the distribution of weed seeds in Tithonia diversifolia dominated fields and to evaluate the effect of leaf, stem and root extracts of T. diversifolia on the emergence of weed seeds in a southern Guinea savanna agro-ecology of Nigeria. To achieve the stated objectives, soil samples were taken from T. diversifolia dominated field and enumerated using direct seedling germination method. The phytosociological survey and growth parameters of T. diversifolia were assessed with the aid of permanently fixed quadrats measuring 0.5 m x 0.5 m placed at 1 m interval between quadrats during the rainy seasons (May– November, 2014 and 2015). The aqueous extracts of the leaf, stem, root and whole plant of T. diversifolia were prepared and applied to soil samples taken from different arable fields. The results of the study shows that 23 weed species belonging to 19 genera and 12 families were enumerated in the seedbank and 65 % of emerged weed seedlings were found between 0-10 cm soil depth. Digitaria gayana contributed (21.90 - 24.45 %), Brachiaria lata (17.07 – 19.24 %) while T. diversifolia (8.53 – 11.58 %). The similarity between the composition of the seedbank and that of the established vegetation was 24.42. The aqueous extract of the whole plant of T. diversifolia was found to have suppressed the emergence of 80.29 % weed seedlings, stems extract 79.57 %, leaves extract 74.35 % while the root extract suppresses 55.95 %. This study indicates that T. diversifolia has the potential to interrupt emergence of most weed species. It can further be used as a tool to formulate new eco-friendly bio-herbicides to control weeds in agro-ecosystems. Keywords: Allelopathy, Aqueous extracts, Seedbank, Tithonia diversifolia , Weed emergence

Suitability of Wild Oat (Avena fatua), False Cleavers (Galium spurium), and Volunteer Canola (Brassica napus) for Harvest Weed Seed Control in Western Canada

As chemical management options for weeds become increasingly limited due to selection for herbicide resistance, investigation of additional nonchemical tools becomes necessary. Harvest weed seed control (HWSC) is a methodology of weed management that targets and destroys weed seeds that are otherwise dispersed by harvesters following threshing. It is not known whether problem weeds in western Canada retain their seeds in sufficient quantities until harvest at a height suitable for collection. A study was conducted at three sites over 2 yr to determine whether retention and height criteria were met by wild oat, false cleavers, and volunteer canola. Wild oat consistently shed seeds early, but seed retention was variable, averaging 56% at the time of wheat swathing, with continued losses until direct harvest of wheat and fababean. The majority of retained seeds were >45 cm above ground level, suitable for collection. Cleavers seed retention was highly variable by site-year, but generally greater than wild oat. The majority of seed was retained >15 cm above ground level and would be considered collectable. Canola seed typically had >95% retention, with the majority of seed retained >15 cm above ground level. The suitability ranking of the species for management with HWSC was canola>cleavers>wild oat. Efficacy of HWSC systems in western Canada will depend on the target species and site- and year-specific environmental conditions.

A Soil Probe System to Evaluate Weed Seed Survival in Soil Disinfestation Trials

Weed seed viability is an important parameter to assess the efficacy of soil disinfestation methods like fumigation and steam. In field experiments, seed samples are commonly placed in permeable bags and buried at several depths in soil before the application of soil disinfestation treatments. The seed samples are recovered several days to weeks after treatment and then seed viability is determined in the laboratory. The process of sample installation and recovery is time consuming and may expose personnel to hazardous conditions such as heat or fumigants. Described is a custom soil probe system, developed to simplify installation and recovery of weed seeds from soil. Each soil probe is capable of holding weed seed samples at three different depths up to 30 cm. The following hypothesis was tested: viability of weed seeds is similarly affected by soil disinfestation treatments whether the seeds were contained in the soil probe system or seed bag assays. Two different soil disinfestation trials were conducted: (1) a repeated micro-plot study (USDA Salinas, 1 m-2), using steam as a soil disinfestation treatment and (2) a field study in a commercial strawberry field with 1,3-dicloropropene plus chloropicrin (Pic-Clor 60) as soil disinfestation method. In both studies, seed viability of burning nettle, common knotweed, and common purslane (tetrazolium assay) and germination rates of yellow nutsedge tubers were assessed. Results indicate that the soil probe system can be used as an alternative to the seed bag assay to assess weed control efficacy of described soil disinfestation methods.

A survey of weed seed contamination of rice paddy in Cambodia

SummaryCambodia has experienced a rapid shift from transplanted to hand broadcast seeded rice, with a consequent increase in seeding rates from 25–30 to 100–200 kg ha−1. To reduce costs, farmers keep their own seed for sowing with the risk of greater weed seed contamination of the sowing seed. A survey of weed seed contamination in harvested rice paddy was conducted in two provinces of Cambodia (Battambang and Takeo) at the end of the wet season in 2016. Farmers were interviewed about rice‐seeding practices, and a total of 110 farmers' fresh paddy samples were inspected for weed seed contamination from the two provinces. Sowing seed samples collected from 28 seed producer lots and 71 samples of farmer‐kept seed were also analysed for weed seed contamination. In both provinces, the majority of farmers kept their own seed or bought seed from a neighbour. Farm‐kept seed for sowing accounted for 88% of sown seed in Battambang and 89% in Takeo. Seeds of 41 different weed species from 13 plant families were found in the farmers' freshly harvested paddy samples. Overall, farmers managed to reduce the number of weed propagules by 60% and seed producers by 95%. There was no significant difference between farmer‐kept seed and seed producer/seed company seed for the total number of weed seeds present. When shown photos, farmers' rankings of the 10 most common weed species found in freshly harvested paddy did not closely correspond to the actual weed seed frequency in the paddy. When farmers were asked to rank the frequency of weeds in their fields without the option to choose from a list, they ranked the weeds differently. Farmers ranked Ischaemum rugosum, Echinochloa spp. and Fimbristylis miliacea as the three most frequent weed species in their fields. The most frequent weeds in harvested paddy, apart from weedy rice, were I. rugosum and Melochia corchorifolia. Farmers did not rank M. corchorifolia as a frequently occurring weed, and most farmers could not recognise M. corchorifolia from photographs. The priority for improved seed hygiene is to place the emphasis on assisting farmers to further improve their seed purification techniques and to caution them to inspect seed before purchasing from neighbours, seed producers and seed companies in the absence of the implementation of seed certification regulation.

Seasonal Foraging by Forest Mice Enhances Loss of Weed Seeds from Crop—Field Edges

Abstract Native seed predators, such as mice (Peromyscus spp.) and ground beetles (Carabidae), consume weed seeds and waste grain within agricultural fields and thus provide a potentially important service to farmers. Most previous investigations of agricultural seed predation services have focused on within-field factors that affect rates of seed removal and consumption by field-resident seed predators. However, seasonal migrants from adjacent non-crop habitats may also contribute to removal of weed seed, particularly along field edges. We investigated whether rates of weed seed removal within fields increased during summer crop growth when Peromyscus leucopus noveboracensis (White-Footed Mouse), a ubiquitous forest-dwelling rodent in the eastern US, seasonally migrates into crop fields from adjacent forested woodlots. We used exclosure experiments to quantify the relative number of Setaria faberi (Giant Foxtail) seeds removed from seed trays by vertebrate and invertebrate seed predators within 4 corn fi...

Winter ecology of prairie deer mice (Peromyscus maniculatus bairdii) in cultivated habitats: Implications for agricultural ecosystem services

Abstract Prairie deer mice ( Peromyscus maniculatus bairdii ) are permanent residents of row-crop fields in the Midwestern United Sates, and may provide ecosystem services by regulating weed seed and waste grain populations. Seed predation is especially critical in the months of highest seed availability following crop harvest, and is dictated by population density and individual patterns of diet choice. We used a combination of spatial mark-recapture demographic and stable isotope dietary analyses to investigate the ecology of prairie deer mice during this critical over-winter period within corn and soybean agro-ecosystems of west-central Indiana. Winter prairie deer mouse populations were robust in the row-crop habitats we sampled, with densities typically > 13 individuals/ha but variable among trapping grids and throughout winter. Apparent survival of individuals also varied throughout winter (57–79% monthly survival rate), and mean over-winter (December–April) survival of adults was 21%. Winter diets were dominated by waste grain, with corn and soybean contributing 55% and 77% of diet for mice sampled in corn and soybean fields, respectively. Weed seeds contributed less (2–27%) to winter diets. Based on our results and published field metabolic rates, we estimate that prairie deer mice consume 6.3 kg/ha of waste corn and 7.1 kg/ha of waste soybean seeds during the non-growing season. Collectively, our results suggest that prairie deer mice make meaningful contributions to reducing waste-grain populations during winter in post-harvest row-crop fields, during a time of year when most other seed predators are inactive.

Ethnoarchaeological Study of Noog (Guizotia abyssinica (L. f.) Cass., Compositae) in Ethiopia

ABSTRACTEthnoarchaeological research was conducted on traditional agriculture and use of noog (Guizotia abyssinica (L.) Cass.) as well as its wild progenitor, mech (Guizotia scabra (Vis.) Chiov) in present day Ethiopia. The study revealed technological and social aspects of this oil crop. Various traditional processing methods (field and household), division of labor, and economical and cultural values are outlined and described. The study shows the probability of charred remains occurring as a result of field processing noog and household processing of noog and mech. It is, however, difficult to differentiate, based on residue composition, the various field processing activities because of similarity of components and absence of weed seeds associated with the noog crop. The tools used in the processing do not leave evidence in the archaeological record indicative of the presence of noog and mech.

Gibberellic and kaurenoic hybrid strigolactone mimics for seed germination of parasitic weeds.

Parasitic weeds are widespread and cause significant losses in important crops. Their germination requires the detection of crop-derived molecules such as strigolactones. Strigolactone mimics are germination-inducing molecules with the potential to apply a suicidal germination strategy for seed bank control of parasitic weeds. The D-ring, which is instrumental in the germination process of seeds of parasitic weeds, was attached to gibberellin (GA3 ) and kaurenoic acid as the scaffold. It was shown that indeed strigolactone mimics prepared from GA3 and kaurenoic acid are active as stimulants when a D-ring is present; some of the mimics are as active as GR24. The starting molecules were plant hormones that had previous growth-regulating activity in other organisms and the products showed enhanced activity towards parasitic weeds. The information generated may contribute to a better understanding of the germination biochemistry of the weed species used. Further research is required in this area but it is clear that the results are promising. © 2017 Society of Chemical Industry.

Is heat treatment a viable option for destroying weed seeds in biosecurity risk goods?

The prevention of biosecurity threats is an international priority and the development of improved phytosanitary treatment technologies is part of New Zealand’s biosecurity science strategy. Twelve temperature/time treatments were investigated as potential methods to devitalise weed seeds. Six weed species, Digitaria violascens, Eleusine indica, Lepidium virginicum, Plantago lanceolata, Portulaca oleracea and Sonchus oleraceus were exposed to treatments of 50˚C, 60˚C or 70˚C each for 1.5 h, 4 h, or 15 h. The efficacy of these treatments was compared with those of two industry standards: (i) 85˚C for 15 h at 40% RH; and (ii) methyl bromide (80 g/m3) for 24 h. The standard treatments were significantly more effective at devitalising weed seeds than the experimental treatments. This study showed that temperatures below 85˚C are generally insufficient for devitalising seeds of the weed species examined.

Effects of resource distribution on overwinter foraging by mice in agricultural fields and the implications for maize volunteer control

Abstract Seed predation may be an important ecosystem service for controlling glyphosate–resistant crop volunteers, which are a growing management concern in conventional cropping systems that rely heavily on pesticide based management. In the Midwest USA, prairie deer mice ( Peromyscus maniculatus ) are important seed predators, removing unwanted weed seeds and waste grain from the soil surface all year round. In this study, we examined how the spatial distribution of experimental maize ( Zea mays ) seed patches influenced overwinter foraging, mouse populations and waste grain removal in conventional crop fields. We predicted that (1) individual mice will increase foraging on maize waste grain in fields with many small maize seed patches compared to fields with a few large maize seed patches (functional response) and (2) more mice will forage in fields with many small seed patches than in fields with a few large seed patches (numerical response). We found mouse functional responses were not influenced by the spatial distribution of maize seed patches nor did mice respond numerically to seed addition in general. Mice did, however, remove 59–66% (94–106 kg ha −1 ) of the maize seeds, providing a valuable ecosystem service. Our work shows that prairie deer mice are able to remove large amounts of waste grain from the soil surface over winter, supporting the hypothesis that overwinter seed predation by mice can drastically reduce volunteer maize densities in conventional crop fields. Future research should further examine what management practices (such as practicing no-till) increase mouse abundance and foraging efficacy, so that management strategies that maximize seed predation can be developed.

Efficacy of the Integrated Harrington Seed Destructor on Weeds of Soybean and Rice Production Systems in the Southern United States

Herbicide‐resistant weeds affect every major cropping system today. Worldwide, there are 47 and 51 confirmed cases of herbicide‐resistant weed populations in soybean [Glycine max (L.) Merr.] and rice (Oryza sativa L.) production systems, respectively. Alternatives to herbicides are necessary to help combat herbicide‐resistant weeds. The integrated Harrington Seed Destructor (iHSD) has been developed to destroy weed seeds during crop harvest but has yet to be tested on weeds in soybean or rice. Thus, the objective of this research was to determine the effectiveness of the iHSD in soybean and rice and to evaluate any limitations. Three experiments were conducted using a stationary iHSD mill. First, the efficacy of the iHSD was evaluated on weed seeds incorporated into soybean residue or rice chaff. Second, varying soybean chaff feeding rates were tested to determine the amount that could be processed without interfering with weed seed destruction. Third, varying soybean chaff moisture levels were tested to determine any limitations that high moisture content may have on the iHSD. The iHSD demonstrated high weed seed destruction efficacy (<1% survival) for 11 of the 12 weed species of soybean. Common cocklebur (Xanthium strumarium L.) seed had 3% survival. In rice, <1% survival was observed in all weed species. The soybean feeding rate and moisture experiments yielded <1% survival across all treatments. These results show that the use of the iHSD can be highly effective in soybean and rice production for reducing inputs to the soil seedbank. These studies highlight the promising seed destruction potential of the iHSD but also demonstrate opportunities for further research evaluating the iHSD as a combine‐fitted system operating under commercial scale production fields.

Factors Affecting Weed Seed Devitalization with the Harrington Seed Destructor

The Harrington Seed Destructor (HSD), a novel weed control technology, has been highly effective in Australian cropping systems. To investigate its applicability to conditions in western Canada, stationary threshing was conducted to determine the impact of weed species, seed size, seed number, chaff load, and chaff type on efficacy of seed destruction. Control varied depending on species, with a range of 97.7% to 99.8%. Sieve-sized volunteer canola seed had a linear relationship of increasing control with increasing 1,000-seed weight. However, with greater than 98% control across all tested seed weights, it is unlikely that seed size alone will significantly influence control. Consistently high levels of control were observed at all tested seed densities (10 seeds to 1 million seeds). The response of weed seed control to chaff load was quadratic, but a narrow range of consistently high control (>97%) was again observed. Chaff type had a significant effect on weed seed control (98% to 98.6%); however, seed control values in canola chaff were likely confounded by a background presence of volunteer canola. Overall, the five parameters studied statistically influence control of weed seeds with the HSD. However, small differences between treatments are unlikely to affect the biological impact of the machine, which provides high levels of control for those weed seeds that can be introduced into the harvester.

Seed Retention of Palmer amaranth (Amaranthus palmeri) and Barnyardgrass (Echinochloa crus-galli) in Soybean

Harvest weed seed control is an alternative non-chemical approach to weed management that targets escaped weed seeds at the time of crop harvest. Relatively little is known on how these methods will work on species in the US. Two of the most prominent weeds in soybean production in the midsouthern US are Palmer amaranth and barnyardgrass. Typically, when crop harvesting occurs the weed seed has already either shattered or is taken into the combine and may be redistributed in the soil seedbank. This causes further weed seed spread and may contribute to the addition of resistant seeds in the seedbank. There is little research on how much seed is retained on different weed species at or beyond harvest time. Thus, the objective of this study was to determine the percentage of total Palmer amaranth and barnyardgrass seed production that was retained on the plant during delayed soybean harvest. Retained seed over time was similar between 2015 and 2016, but was significantly different between years for only Palmer amaranth. Seed retention did not differ between years for either weed species. Palmer amaranth and barnyardgrass retained 98 and 41% of their seed at soybean maturity and 95 and 32% of their seed one month after soybean maturity, respectively. Thus, this research indicates that if there are escaped Palmer amaranth plants and soybean is harvested in a timely manner, most seed will enter the combine and offer potential for capture or destruction of these seeds using harvest weed seed control tactics. While there would be some benefit to using HWSC for barnyardgrass, the utility of this practice on mitigating herbicide resistance would be less pronounced than that of Palmer amaranth because of the reduced seed retention or early seed shatter.

Effect of Temperature and Retention Time in Cattle Slurry on Weed Seed Viability

Effect of Temperature and Retention Time in Cattle Slurry on Weed Seed Viability