Alfalfa (Medicago sativa L.) hosts several species of aphid, Acyrthosiphon pisum (Harris), Aphis craccivora Koch and Therioaphis trifolii (Monell). The preference of the aphids of alfalfa plants for dense assemblies or individual plants, as well as for healthy or infested plants, was investigated in the field as in the laboratory. Years of field research have revealed the specific preferences of all three species of aphid. A. pisum and T. trifolii are most commonly found in alfalfa crops, while A. craccivora is mostly found on alfalfa weeds. Also, a single species of aphid alone is usually present on a plant. In order to determine the reason for this clear preference and to establish whether at the very beginning, i.e. at the stage of choosing a host, aphid species distance themselves from each other, we tested the effect of the volatiles of healthy and infested plants on their attractiveness to aphids. A. craccivora is repelled by the volatiles of dense crops and plants previously infested with one of the other two species. A. pisum and T. trifolii choose a dense assembly of plants, repelled by the volatiles of plants previously infested with A. craccivora. A. pisum displays the weakest competitive traits, and A. craccivora the strongest. This research showed that competition between aphid species does not occur only when they find themselves on the same plant at the same time, fighting for resources, but also in the choice of plant, in order to avoid later competition.

This research communication presents a study evaluating the effects of dried sainfoin (Onobrychis viciifolia) supplemented to dairy goats on their milking performance and feed protein efficiency under commercial conditions. During July and August 2015, a herd of 20 Alpine goats was divided into two treatments (n = 10), balanced by milk yield and days in milk. They were supplied with either 700 g/d sainfoin pellets (condensed tannins: 4.0 g/kg DM) or 700 g/d lucerne (Medicago sativa) pellets (condensed tannins: 0.3 g/kg DM). The goats remained in one herd and were separated by treatments only during milking. In the milking parlour each goat received 350 g of the respective pellets, twice daily. During the day, the herd had 5 h access to a high-quality pasture (crude protein >200 g/kg DM), whilst during the rest of the day and the night animals were housed and offered grass hay ad libitum. The experiment lasted for seven weeks. Individual milk yields and composition were controlled in weeks 1, 3, 5, and 7 after the start of the experiment. No differences between the treatments were found, either for milk, protein or urea yields, nor for protein, urea and fat concentrations. Urea to protein ratio in milk was lower with the sainfoin treatment. In conclusion, sainfoin compared to lucerne, supplied for 7 weeks to dairy goats at approximately 25% of the diet, had only weak beneficial and no adverse effects on milking performance, milk composition and feed protein efficiency under commercial conditions of pasture-based dairy production.

Establishment of alfalfa by interseeding it with corn planted for silage can enhance crop productivity but weed management is a challenge to adoption of the practice. Although a simple and effective approach to weed management would be to apply a glyphosate-based herbicide, concerns about herbicide resistance and limitations in available alfalfa varieties exist. Field experiments were conducted to compare the efficacy and selectivity of PRE, POST, and PRE followed by POST herbicide programs to a glyphosate-only strategy when interseeding alfalfa with corn. Experiment 1 compared PRE applications of acetochlor, mesotrione, S-metalochlor, metribuzin, and flumetsulam. Results indicate that acetochlor and metribuzin, and S-metalochlor used at a rate of 1.1 kg ai ha−1 were the most effective and selective PRE herbicides 4 wk after treatment (WAT), but each resulted in greater overall weed cover than glyphosate by 8 WAT. Experiment 2 evaluated applications of bentazon, bromoxynil, 2,4-DB, and mesotrione at early and late POST times. Several herbicides used POST exhibited similar effectiveness and selectivity as glyphosate, including early applications of bromoxynil (0.14 kg ai ha−1) and 2,4-DB (0.84 or 1.68 kg ai ha−1), as well as late applications of bromoxynil (0.42 kg ai ha−1), 2,4-DB (0.84 kg ai ha−1), and mesotrione (0.05 or 0.11 kg ai ha−1). A third experiment compared applications of acetochlor PRE, bromoxynil POST, and a combination of acetochlor PRE with bromoxynil POST. All treatments were effective and safe for use in this interseeded system, although interseeded alfalfa provided 65% to 70% weed suppression in corn planted for silage without any herbicide. Herbicide treatments had no observable impacts on corn and alfalfa yields, so weed management was likely of limited economic importance. However, weed competitiveness can vary based on several different factors including weed species, density, and site-specific factors, and so further investigations under different environments and conditions are needed.

Excessive flavour in lamb meat is undesirable for consumers and can prompt purchase resistance. Volatile indoles responsible for off-flavours accumulate more in the fat of lambs on pasture than on grain and are enhanced when lambs graze alfalfa. Here, we investigated whether barley supplementation of lambs grazing alfalfa influences meat sensory quality. Using three groups of 12 male Romane lambs, we compared three feeding regimes: alfalfa grazing (AG), alfalfa grazing + daily supplementation with barley (29 g/kg live weight0.75, AGS) and stall feeding with concentrate and hay (SF). As some of the compounds involved in meat sensory traits may act as dietary biomarkers, we also investigated potential implications for meat authentication. Although barley represented 38% of the diet in AGS lambs, it did not offer any advantage for animal average daily gain or parasitism level. Animal performance, carcass weight and fatness did not differ between feeding regimes. Dorsal fat firmness tended to be greater in AG than AGS and greater in AGS than SF. Skatole and indole concentrations in perirenal and dorsal fat were lower in SF lambs than in AG and AGS lambs (P<0.01 to P<0.0001), but did not differ between AG and AGS lambs. Yellowness, chroma and hue angle of perirenal fat were lower in SF lambs than in AG and AGS lambs (P<0.001), but did not differ between AG and AGS lambs. Absolute value of the mean integral for both perirenal fat and subcutaneous caudal fat (AVMIPF and AVMISC), quantifying the intensity of light absorption by carotenoids in perirenal and subcutaneous caudal fat, respectively, were lower in SF lambs than in AG and AGS lambs (P<0.0001 for both comparisons), but did not differ between AG and AGS lambs. Meat colour was unaffected by the treatment. We confirm that lambs grazing alfalfa accumulate high levels of volatile indoles in their fat, but we show that barley supplementation to lambs grazing alfalfa is not effective in reducing fat volatile indoles concentration and excessive odour/flavour in the meat. We also confirm that both perirenal fat skatole concentration and AVMIPF are of interest for discriminating lambs that grazed alfalfa from lambs that were stall-fed, and we show that they are not effective for discriminating supplemented from non-supplemented grazing lambs.

Alfalfa is recommended as a rotational crop in corn production, due to its ability to contribute to soil nitrogen (N) and carbon (C) stocks through atmospheric N2 fixation and above- and belowground biomass production. However, there is little information on how alfalfa management practices affect contributions to soil and subsequent corn crop yields, and research has not been targeted to organic systems. A study was conducted to determine the effects of alfalfa stand age, cutting frequency and biomass removal on soil C and N status and corn yields at three organically managed Minnesota locations. In one experiment, five cutting treatments were applied in nine environments: two, three and four cuts with biomass removal; three cuts with biomass remaining in place; and a no-cut control. In the other experiment, corn was planted following 1-, 2-, 3- or 4-year-old alfalfa stands and a no-alfalfa control. Yield was measured in the subsequent corn crop. In the cutting experiment, the two- and three-cut treatments with biomass removal reduced soil mineral N by 12.6 and 11.5%, respectively, compared with the control. Potentially mineralizable N (PMN) was not generally affected by cutting treatments. The three-cut no-removal increased potentially mineralizable C by 17% compared with the other treatments, but lowered soil total C in two environments, suggesting a priming effect in which addition of alfalfa biomass stimulated microbial mineralization of native soil C. Although both yields and soil mineral N tended to be higher in treatments where biomass remained in place, this advantage was small and inconsistent, indicating that farmers need not forgo hay harvest to obtain the rotational benefits of an alfalfa stand. The lack of overall correlation between corn grain yields and mineral and potentially mineralizable N suggests that alfalfa N contribution was not the driver of the yield increase in the no-removal treatments. Alfalfa stand age had inconsistent effects on fall-incorporated N and soil N and C parameters. Beyond the first year, increased alfalfa stand age did not increase soil mineral N or PMN. However, corn yield increased following older stands. Yields were 29, 77 and 90% higher following first-, second- and third-year alfalfa stands than the no-alfalfa control, respectively. This indicates that alfalfa may benefit succeeding corn through mechanisms other than N contribution, potentially including P solubilization and weed suppression. These effects have been less studied than N credits, but are of high value in organic cropping systems.

Research was conducted to determine the potential for allelopathy to occur in pastures infested with bitter sneezeweed. Aqueous extracts of bitter sneezeweed leaves reduced alfalfa and Italian ryegrass seedling growth as much as 50% at concentrations of 0.5% (w/v). Leaf extracts were more phytotoxic than either stem or root extracts and seedling growth was reduced more than seed germination. Bitter sneezeweed tissue mixed in potting soil at concentrations as low as 0.3% w/w reduced alfalfa seedling numbers by 43%, plant height by 26%, and foliage dry matter production by 54% compared to plants cultured in soil without bitter sneezeweed leaf tissue. The potential concentration of bitter sneezeweed leaf material in soil in the pasture ecosystem was determined to be 0.5% w/v in the liquid phase and 0.2% w/w in the solid phase. Alfalfa seedling growth was reduced by 70% when germinating seed were placed under a bell jar with a potted mature bitter sneezeweed plant compared to control seedlings. A potential exists for bitter sneezeweed interference with developing alfalfa and Italian ryegrass seedlings following fall interseeding into pastures infested with bitter sneezeweed.

Teliospores of Sphacelotheca holci Jack. [= S. cruenta (Kuhn.) Potter] infected johnsongrass [Sorghum halepense (L.) Pers. # SORHA) systemically after inoculation of cut stems in greenhouse studies. A preliminary host range test in the greenhouse revealed that no infection occurred on four varieties of sorghum (S. vulgare L.) and three cultivars of sudangrass (S. Sudanese L.). Infected johnsongrass plants grown in the greenhouse exhibited reduced vegetative growth and altered morphological characteristics compared to healthy johnsongrass plants. The aboveground biomass and lateral rhizome expansion of smutted johnsongrass field transplants were significantly lower than that of uninfected plants. Significant correlations between fraction of johnsongrass stems infected and plant weight, and basal area of plants were observed in field studies. Corn (Zea mays L.) and alfalfa (Medicago sativa L.) grown in competition with johnsongrass, and johnsongrass infected with S. holci reduced the aboveground biomass and rhizome length of johnsongrass plants significantly, compared to that of uninfected johnsongrass plants grown alone in greenhouse studies. Uninfected johnsongrass plants also exhibited higher plant weight than infected plants when both were grown in competition with alfalfa, regardless of the alfalfa planting density in the greenhouse or when measured after 3 months in field trials.

Seed of yellow foxtail (Setaria lutescens (Weigel) Hubb.) biotypes collected in Connecticut, Iowa, Massachusetts, Pennsylvania, and California were grown under field conditions at Davis and Woodland, California. Three biotypes collected in California alfalfa (Medicago sativa L.) fields all exhibited only a prostrate growth habit; the biotypes from the eastern United States all had an upright growth habit. The California biotypes were always glaucous; those collected in the east were not glaucous. Ratio of culm height to culm length were near unity for the eastern biotypes but averaged 1.5 to 1.7 for the California biotypes. Variations existed between biotypes in days from planting to heading, number of nodes per culm, leaf shape and size, and in final dry weight per plant.

Dicamba and 2,4-D, which are used prior to seeding in conservation tillage systems, were applied in late fall and early spring to determine their residual effect on subsequent spring-seeded crops. The herbicides 2,4-D ester and 2,4-D amine with dicamba or glyphosate, applied 0 or 15 d prior to spring seeding, damaged canola, peas, lentils, and alfalfa. The legumes were damaged by spring-applied dicamba. There was also a slight reduction in the total dry matter yield of wheat and barley by 2,4-D applied in spring prior to seeding. All crops tested, except lentils, were tolerant of recommended fall applications of 2,4-D for the control of winter annual flixweed and field pennycress.

Tolerance and subsequent yield response of established alfalfa, red clover, alsike clover, sainfoin, birdsfoot trefoil, and cicer milkvetch to sethoxydim and fluazifop spring applied and to hexazinone, metribuzin, and terbacil fall applied were determined in a field study. All legumes tolerated sethoxydim. Fluazifop was safe on all legumes except sainfoin. Alfalfa and cicer milkvetch tolerated hexazinone, metribuzin, and terbacil. Alfalfa dry matter yield was not affected by any of the herbicide treatments, but cumulative cicer milkvetch yield increased 9% over a 3-yr period with hexazinone applications. Sainfoin yield increased 20% with hexazinone and terbacil treatment. Hexazinone injured red clover and reduced yield. Alsike clover was the most susceptible legume to the residual herbicides. Weed dry matter yield associated with the legumes indicated that alfalfa and sainfoin were the most and the least competitive species, respectively. Plots treated with hexazinone contained the least amount of weeds, regardless of the legume species. Field peas seeded in rotation was not affected by herbicide residues; however, residues from terbacil applied at 1.0 kg/ha reduced seed yield of lentils.

Dry bean (Phaseolus vulgaris) can be grown as a local food source and as an alternative to soybean (Glycine max) to diversify organic crop rotations. To understand the benefits of diversification of organic cropping systems, the effects of preceding alfalfa (Medicago sativa) and corn (Zea mays) crops on yields of five dry bean types and one soybean type, and the effect of bean type on following spring wheat (Triticum aestivum) yields, were tested at four Minnesota locations. Dry bean and soybean yields following alfalfa were 25% greater than yields following corn at two of four locations, though bean yields following corn were greater at one location. A preceding alfalfa crop benefited bean yields at locations where hog manure or no manure was applied to corn, whereas bean yields following corn fertilized with cow manure were similar to or greater than bean yields following alfalfa. Among dry bean types, black bean yielded similarly to soybean at three of four locations, but dark red kidney bean consistently yielded 25–65% lower than soybean. Navy, pinto and heirloom dry bean types yielded similarly to soybean at two of four locations. Across locations, weed biomass was 3–15 times greater in dry bean than in soybean and dry bean yield response to weed competition varied among bean types. However, dry bean, regardless of the preceding crop, demonstrated the potential to produce yields comparable with soybean in organic systems and the substitution of dry bean for soybean did not affect subsequent wheat yields. More studies are needed to identify nitrogen fertility dynamics in organic systems as they relate to dry bean yield.

The effect of supplementing high-quality fresh forage, mainly based on alfalfa, to growing lambs fed with decreasing levels of total mixed ration (TMR) was studied on intake, digestion and ruminal environment. In total, 24 catheterized lambs (25.2±3.67 kg) housed in individual metabolism cages were assigned to one of four treatment diets: ‘TMR100’: TMR offered ad libitum; ‘TMR75’ and ‘TMR50’: TMR at a level of 0.75 and 0.50 of potential intake, respectively, complemented with fresh forage without restriction; ‘TMR0’: only fresh forage ad libitum. The feeding behavior, nutrient intake and digestibility, kinetics of passage and rumen environment were evaluated. As the level of TMR in the diet decreased, lambs increased the forage intake and spent more time eating and ruminating, less time resting and demonstrated a higher rate of intake. Those changes resulted in a higher nutrient intake of dry matter, organic matter, nitrogen, NDF and ADF, but a slightly lower organic matter digestibility, while no differences were detected in the output rate of particles. As a consequence, with the decrease of TMR and increase of forage intake, the ingested energy increased. Higher ruminal pH and NH3–N concentrations were observed for lower levels of TMR in the diet. The total volatile fatty acids, acetate and propionate concentrations presented a quadratic response. Total volatile fatty acids and acetate concentrations were higher and propionate concentration was lower in lambs consuming mixed diets (TMR50 and TMR75). We concluded that the inclusion of high-quality fresh forage in a combined diet with TMR in lambs had positive effects on nutrient intake without negative consequences on digestion and rumen environment.

The objective of this experiment was to determine the effectiveness and crop safety of glyphosate vs. alternative herbicides for weed control in glyphosate-resistant alfalfa. Glyphosate-resistant alfalfa was established at two sites in Pennsylvania in 2004 and in 2005, and herbicides were applied either PRE or POST for weed control. Data were collected on herbicide performance, alfalfa and weed yield, and forage quality. Alfalfa forage response to weed control was variable and depended on weed severity. A single or split application of glyphosate provided similar or better weed control than conventionally based herbicide programs. The most differences from weed control occurred during the first harvest and dissipated in subsequent harvests. Cumulative alfalfa yield for the establishment year of the spring seeding was 26% lower in the untreated check relative to the mean of the herbicide-treated plots in 2004; but no differences were detected in 2005. Forage quality was highest where weed content of the forage was lowest. Effective management of weeds with herbicides during alfalfa establishment can improve forage yield and quality, and weed control is particularly important when summer annual weed populations are severe and emerge with the crop.

The introduction of glyphosate-resistant (GR) alfalfa offers a new weed management system for alfalfa establishment; however, alfalfa seeding rates are based on conventional cultivars. Determining optimum seeding rates allows forage producers to maximize yield, quality, and profitability with GR alfalfa. Field experiments were established in 2005 and 2006 to determine the effect of seeding rate and weed control on GR alfalfa yield, forage quality, and persistence up to 3 yr after establishment. Seeding rates of 4.5, 9.0, and 18 kg ha−1 were evaluated. Weed control methods during the seeding year included no herbicide, glyphosate applied once before the first harvest, and glyphosate applied once before the first harvest and then 7 to 10 d following subsequent harvests. Alfalfa yield was greater at higher seeding rates and when weeds were removed with glyphosate. Season forage yields were the greatest with the 18 kg ha−1 seeding rate and where no herbicide was applied. Weed biomass often was lower at the higher seeding rates and was 91 to 98% lower in the glyphosate treatments compared to the nontreated. Forage quality was not affected by seeding rate but varied by herbicide treatment depending on establishment year. Plant density increased with seeding rate and treatment effects persisted for three growing seasons. Herbicide treatment did not affect stand density as greatly as seeding rate and did not influence stand longevity.

Alfalfa is an important forage crop in North America, and it can also be found as a roadside weed in alfalfa-growing regions. Weediness and invasiveness are greatly facilitated by establishment ability, yet little is known about the ability of alfalfa to establish in competitive environments such as roadsides. The primary objective of this study was to estimate the degree of alfalfa establishment without managed cultivation under different seed-dispersal times and disturbance regimes. The study had a split-plot design with two main plots (spring and fall seed dispersal) and five subplots (mowing, soil disturbance, herbicide spray, seedbed, and undisturbed control). The study examined establishment, growth attributes, and reproductive output of alfalfa in response to these treatments. Alfalfa establishment in the undisturbed grass swards ranged between 0.5 and 9.7% (out of the total number of seeds dispersed) across the dispersal times. The density of alfalfa in fall-seeded plots was about 82% lower than in spring-seeded plots. Soil disturbance reduced the density of alfalfa to < 50% of the initial density. Generally, low plant densities were compensated over time by increased numbers of shoots and reproductive units (racemes and pods) per plant. Herbicide application (2,4-D + dicamba) effectively controlled all emerged alfalfa plants, but in some cases, seedling recruitment was observed in the years following herbicide application. Although mowing did not kill alfalfa plants, mowed plants did not produce mature seeds, and as such, mowing may be useful in restricting the reproductive success and population growth of alfalfa. Overall, it is evident that alfalfa is capable of establishing in competitive environments (such as roadside habitats) and rapidly recovering from moderate disturbances. The results of this study have implications for managing roadside alfalfa and for designing novel trait-confinement protocols for alfalfa.

Sensitivity of alfalfa to acidity and aluminium (Al) toxicity in soil is the major limiting factor in broadening of its growing area. Due to lack of Al tolerance in primary alfalfa germplasm, there is a need for transfer of genes for Al tolerance from other Medicago germplasm. One of the identified sources of Al tolerance is M. sativa ssp. caerulea accession PI 464724, which was used as a female parent in our study. The objectives of this study were: (i) obtaining the tetraploid offspring from 2x–4x M. sativa ssp. caerulea – M. sativa ssp. sativa spontaneous crosses, and (ii) development of a breeding strategy for Al/acid tolerance in alfalfa, using M. sativa ssp. caerulea as a source of Al tolerance. Out of eleven fully developed plants, five were morphologically similar to M. sativa ssp. caerulae, while six plants were similar to M. sativa ssp. sativa. All tested plants were fertile, with the pollen viability ranging from 21.45 to 97.09% and the average number of ovules per plant from 8.80 to 12.29. Eleven SSR primer pairs confirmed the hybrid nature of M. sativa ssp. caerulae × M. sativa ssp. sativa offspring. Both the Cluster Analysis and the Principal Coordinates Analysis separated plants in the caerulae type from plants in the sativa type, with one exception. Strategies based on conventional and molecular marker breeding efforts could lead towards development of tolerant alfalfa cultivars and successful crop production on acidic, Al-contaminated soils.

Integrated pest management (IPM) initially focused on insect pest control. More recently, IPM encompasses a broader concept of management, one which crosses several disciplinary boundaries. This article reports results of research dealing with four integrated management decisions for alfalfa (cultivar selection, inset control, weed control, and end-of-season harvest options).

The present study was conducted to determine the optimum age of Holstein dairy calves for an effective inclusion of alfalfa hay (AH) in starter feed on performance, apparent digestibility and feeding behavior. A total of 40 Holstein dairy calves (20 female and 20 male) were used in a completely randomized design in which calves were randomly assigned to one of four different dietary treatments including control (CON) calves fed starter feed without any forage and three treatments consisting of the same starter feed plus 15% chopped AH fed when calves were at the 2nd (AH2), 4th (AH4) or 6th (AH6) week of age. Calves were individually housed and bedded with sand that was replaced every other day. Feed and water were available ad libitum throughout the experiment. Calves were fed milk at 10% of birth BW twice daily until d 57. The study concluded when calves were 73 days old. Starter intake was recorded daily and BW was measured weekly. Data were analyzed as a complete randomized design by MIXED procedures of SAS. Results demonstrate that calves receiving AH treatments numerically consumed more starter feed (0.62 v. 0.78, 0.71 and 0.65 kg/day for CON, AH2, AH4 and AH6, respectively) and had greater average daily gain (ADG) compared with CON (0.48 v. 0.57, 0.49 and 0.49 kg/day for CON, AH2, AH4 and AH6), although the significant difference was observed only between AH2 and CON. Among AH treatments, calves in AH2 had better performance than AH6 in several cases including starter intake, ADG. No detectable differences were observed, however, in apparent dry matter, organic matter or CP digestibility among treatments. Ruminal pH and NH3 concentrations, measured on weeks 4, 6, 8 and 10, were lower for calves fed CON compared with other treatments, with ammonia concentrations decreasing over time. Calves in the AH treatments spent more time eating and ruminating compared with CON. Calves fed CON, however, spent more time on laying down compared with other treatments. Overall, results from the present study illustrated that inclusion of alfalfa in starter feed for calves at 2 weeks of age may improve feed intake, ADG and stimulate rumination in young Holstein dairy calves. Results, however, should be viewed with caution as the number of calves per treatment was small and large calf-to-calf variation may have affected the results reported.

Aphids are important agricultural pests worldwide. Their control is largely based on chemical insecticides. One species that shows important invasive abilities and host-plant-related differences is Therioaphis trifolii (Monell) (Hemiptera: Aphididae). T. trifolii maculata, also known as spotted alfalfa aphid (SAA), can be very injurious to alfalfa crops in certain regions, such as in Saudi Arabia for effective control it is essential to diagnose and monitor the resistance mechanisms in the SAA populations. In the present study, we analysed acetylcholinesterase (ace) target site insensitivity mechanisms. A 650 bp length DNA containing the putative acetylcholinesterase (ace1) precursor was obtained and compared with other Hemipteran species. The sequences of many individual aphids collected from alfalfa crops in Saudi Arabia were analysed for the presence of resistance mutations: no resistance mutations were found at the resistance mutation loci 302; however, the presence of a serine–phenylalanine substitution (S431F) was identified in one individual. The S431F substitution, has been shown to confer significant levels of both organophosphate and carbamate resistance in other aphid species, and is now found for the first time in T. trifolii. We subsequently developed a simple polymerase chain reaction–restriction fragment length polymorphism assays for the S431F mutation, using a TaqI restriction site destroyed by the S431F mutation. The novel diagnostic assay may support the implementation of Insecticide Resistance Management strategies, for the control of SAA in alfalfa crops in the Kingdom of Saudi Arabia, and other countries worldwide.