Field experiments were conducted near Boone, IA, to quantify postdispersal seed predation of common lambsquarters and common waterhemp in corn (2003) and soybean (2004) managed with conventional, reduced, and zero-tillage systems. Seed predation in each tillage regime was quantified using selective exclusion treatments during July through September 2003 and June through October 2004. In addition, the activity density of ground-dwelling invertebrates was estimated with pitfall traps. Choice and no-choice feeding trials were conducted in the laboratory using the most abundant weed seed predators found in the field to determine seed preferences of the potential predator organisms. The greatest seed loss occurred during July and August. In 2003, seed predation was lower in zero tillage than in conventional and reduced tillages, but no differences in seed predation between tillage regimes were observed in 2004. Maximum seed predation for common lambsquarters was 53% in 2003 and 64% in 2004. Common waterhemp seed predation reached 80% in 2003 and 85% in 2004. The majority of seed predation was by invertebrate organisms. The most common invertebrate species captured with pitfall traps were field crickets (Gryllus pennsylvanicusDe Geer [Gryllidae, Orthoptera]) and ground beetles (Harpalus pensylvanicusBurmeister [Coleoptera, Carabidae]). In 2003, field crickets were relatively more abundant in conventional and reduced tillage than in zero-tillage plots. In 2004, field crickets were more abundant in the reduced tillage than in the other two tillage regimes. No differences were detected for ground beetles among tillage regimes (P = 0.57). Choice and no-choice feeding experiments confirmed the preferences of field crickets and ground beetles for common lambsquarters and common waterhemp seeds over the larger seeds of giant foxtail and velvetleaf. Under field conditions, the activity density of field crickets was a significant predictor of common lambsquarters (r2= 0.47) and common waterhemp (r2= 0.53) seed predation. Positive relationships were also detected between the activity density of ground beetles and common lambsquarters (r2= 0.30) and common waterhemp (r2= 0.30) seed predation. This research demonstrated that weed seed predation is an important component affecting weed seedbanks and that crop management practices that favor the activity of predators such as field crickets or ground beetles could influence weed populations. Also, the results suggested that tillage is more important in determining the number of weed seeds available on the soil surface to predators than directly affecting predator activity density.

St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is a warm-season turfgrass primarily used for home lawns and commercial landscapes in the southern United States. New cultivars that possess desirable turfgrass quality (TQ) in combination with improved tolerance to diseases, drought and cold are needed to increase the sustainability of St. Augustinegrass production and maintenance in transitional zones. This study's objectives were to evaluate breeding lines in multienvironment trials across North Carolina to (a) assess relationships among economically important traits, and (b) select genotypes with stable performance across environments. Sixtyone St. Augustinegrass genotypes and five commercial checks were established in replicated field trials at three locations across North Carolina. Entries were evaluated for rate of establishment, TQ, turfgrass stand density, genetic color, leaf texture, uniformity, winter survival, fall color, drought tolerance, and gray leaf spot resistance from 2017 to 2020. Best linear unbiased predictions were used to calculate a selection index to identify elite genotypes across traits. The 10 traits were clustered into three groups: winter survival and fall color; genetic color, leaf texture, and gray leaf spot resistance; and establishment rate, TQ, density, uniformity, and drought tolerance. Selection of the top 10 genotypes using the selection index resulted in positive estimated genetic gains for all 10 traits, indicating it is an effective method for simultaneous selection. Line XSA 14271 outperformed 'Palmetto', 'Raleigh', 'Captiva', and 'Seville', for several traits and was the top-ranked line. It will be advanced to on-farm trials to evaluate sod production traits to assess its potential for commercial release.

Amaranthus palmeri S. Watson (commonly known as Palmer amaranth) is a dioecious species that has become one of the most problematic weeds in the USA, not only because of its high reproduction rate and ability to compete with crops but also because of its rapid expansion of herbicide-resistant biotypes throughout the country in a relatively short period of time. This last aspect is particularly puzzling because A. palmeri is native from the south-western USA, and it was not considered a frequent or problematic weed until the end of the 20th century (Sauer, 1957;Ward et al., 2013). In the last 30 years, there has been an increasing number of reports of this weed species invading agricultural fields throughout the Southern and Midwestern USA (Butts et al., 2016;Webster and Coble, 1997).The increase in the evolution of herbicide-resistant biotypes has been associated with the success of this weed as an invader of agricultural fields (Butts et al., 2016;Ward et al., 2013). But just as importantly, there are multiple factors within a cropping system that should be considered to understand weed species survival and increasing colonisation of agricultural systems. Amaranthus palmeri populations have high levels of genetic di-versity but most is found within populations and very little across populations (Chandi et al., 2013). In other words, due to high rates of gene flow, populations of A. palmeri tend to be similar, at least when considering neutral markers. This information has important practical implications because if most populations are similar, then solutions to manage a particular population should be effective to manage other populations. However, selective forces in agricultural fields can be high enough to overcome gene flow and fix alleles or traits that favour the survival of the weed in a particular cropping system (Karn and Jasieniuk, 2017). The most common and documented case of this situation is herbicide resistance, but other traits with less conspicuous phenotypes

St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] cultivars tend to be susceptible to the southern chinch bug (Blissus insularis; SCB). This insect feeds on the plant by sucking the sap, causing leaf chlorosis and necrosis, and can kill whole lawns. Resistant cultivars can simplify SCB management and reduce insecticide use. However, little research has been conducted to identify resistant germplasm that can be used in breeding. The objectives of this study were to (i) evaluate the level of damage caused by SCB feeding on sixteen St. Augustinegrass genotypes, and (ii) determine the attractiveness and quality of those genotypes to SCB in choice and nochoice scenarios under greenhouse conditions. After a period of 6 wk of exposure in a choice study, SCB feeding damage on St. Augustinegrass [S. secundatum (Walter) Kuntze] cultivars 'FX-10', 'DALSA 0605' (TamStar ® ), 'SS-100' (Palmetto ® ), and pembagrass [Stenotaphrum dimidiatum (L.) Brongn.] accession PI 289729 ranged from 3 to 21%, demonstrating the highest resistance to SCB. Breeding lines XSA 10403, XSA 11168, and XSA 12354 suffered significant damage (>68%), indicating a high susceptibility to SCB. In a no-choice study, '615866' (Seville ® ), 'SS-100' and most breeding lines exhibited intermediate levels of SCB susceptibility, with SCB survival ranging from 35 to 74%. FX-10, 'DALSA 0605', and PI 289729 were not suitable for SCB feeding and oviposition and exhibited two-to five-fold reductions in the number of live SCB and eggs recovered per plant compared to most breeding lines. Several breeding lines proved to have higher levels of tolerance than cultivar 'Raleigh'. The magnitude of the differences between the most resistant and susceptible lines indicates that it is possible to generate biparental populations with enough segregation to conduct QTL mapping for SCB resistance. INTRODUCTIONSt. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] is a warm-season turfgrass mainly grown in the southern coastal states of the United States and in many tropical and sub-tropical regions of the world (Sauer, 1972). Lawn areas planted with this turfgrass species are quickly expanding due to rapid urban development (Liu et al., 2008;