Relative seed yields should be an important measure of the effects of the endophytic fungus Acremonium coenophialum Morgan‐Jones & Gams on relative fitness in tall fescue (Festuca arundinacea Schreb.). Two field experiments were conducted on Cecil sandy‐loam soils (clayey, kaolinitic, thermic Typic Kanhapuldults) to investigate the effects of endophyte infection on seed production and associated traits. The studies used endophyte‐infected and uninfected clones of the same plant genotypes. In Exp. I and II, endophyte infection resulted in 79 and 32% more total seed by weight, 60 and 33% more seeds per plant, 20 and 34% more panicles per plant, and 32 and 4% more seeds per panicle, respectively. The 300‐seed wt. was greater for infected plants in Exp. I but not in Exp. II. Plant genotype ✕ fungal status interactions occurred for all traits except for seeds per plant and seeds per panicle in Exp. II. These interactions occurred largely because the effect of the endophyte varied from no or small increases to significant increases in trait expression for different plant genotypes. The results indicate that endophyte‐infected tall fescue plants have much higher relative fitness for seed production than uninfected plants. Populations with low fungal incidence could rapidly shift toward high levels of infestation during seed increase or in pastures when seed production is allowed, leading to establishment of volunteer plants.

The objective of this study was to determine if feeding carbohydrate supplements with faster degradation rates than corn to dairy cows grazing ryegrass would improve nitrogen capture, milk production, and components. Treatments were grain supplements based on: 1) corn (CORN), 2) barley and molasses (BM), or 3) citrus pulp and molasses (CM). For BM and CM, the diet composition was the same as that of CORN except that a portion of the corn was replaced with barley and molasses or citrus pulp and molasses, respectively, on a dry matter basis. Cows grazed ryegrass (Lolium multiflorum Lam.) pasture. Yield of milk, 3.5% fat-corrected milk, energy-corrected milk, and milk fat, as well as milk fat percentage, were not different among treatments. True milk protein percentage was higher for CORN (2.81%) compared with CM (2.70%), but was not different for BM (2.77%). However, true milk protein yield was not different among treatments. Milk urea N was higher for BM (11.43 mg/dL) compared with both CORN and CM (average: 9.95 mg/dL). There were no differences among CORN, BM, and CM treatments for overall BUN (average: 10.60 mg/dL). At 0400 h, however, cows on CORN had higher BUN than cows on CM (11.43 vs. 9.96 mg/dL), but there were no differences between CORN and BM (average: 11.21 mg/dL) or BM and CM (average: 10.48 mg/dL), and there were no differences among treatments at other time points. The CM diet might have shown more advantage if the pasture crude protein content was higher. Partial replacement of corn with citrus pulp for grazing cows should be further studied using pasture with higher crude protein content. Although cows receiving CM and BM did not produce more milk than cows on CORN, if barley or citrus pulp is less expensive than corn, they may be

The objective of this experiment was to determine whether varying times at which a partial mixed ration was fed, either before or after grazing, affected N utilization from rye pasture and thus affected milk yield and components. Sixteen Holstein cows were fed a partial mixed ration (PMR) either at 0700, 0830, or 1100 h. Cows were milked at 0900 h and turned out to graze at 0930 h. Treatments represented feeding times 2.5 h and 1 h before grazing and immediately after grazing. The study was conducted as a 3 x 3 Latin square with three 17-d periods. There were no significant differences among treatments for pasture intake or yield of milk or milk components. Milk yield, fat %, and protein % were 29.4, 29.6, and 29.3 kg, 3.5, 3.5, and 3.4%, and 3.4, 3.5, and 3.4% for treatments, respectively. The milk urea levels were 15.6, 15.1, and 15.5 mg/dl, and were not different among treatments. Blood samples were collected on the last day of each period at 0645, 0845, 1045, 1200, and 1400 h. Blood urea nitrogen (BUN) was measured as an indicator of ruminal N capture. Concentrations were not significantly different among diets before grazing; however, they were significantly different among all treatments approximately 1 h after cows were removed from pasture. Cows fed at 0700 h, 2 h before grazing, maintained lower BUN levels across the 7 h during which the blood samples were collected. Cows that ate the PMR immediately after grazing maintained the highest BUN. Feeding a PMR to cows that graze at different times before and after grazing affected the capture of ruminal N, as indicated by differences in the levels of BUN, but there was no effect on yield of milk or milk components.

We evaluated the effects of annual ryegrass (Lolium multiflorum Lam.) and phosphorus (P) availability on the dissipation of pyrene added at a concentration of approximately 600 mg kg-1 dry soil in the top 7.5 cm of a Cecil loamy sand (fine, kaolinitic, thermic Typic Kanhapludults) in a 10-month experiment under field conditions in Clemson, South Carolina. Plastic canopies were installed to prevent flooding of plots and raindrop dispersion of pyrene. Treatment factors were pyrene, vegetation, and available P levels. Each of the eight treatments had four replicates. The soil was adjusted to low and high P concentrations (an average of 41 and 66 kg extractable P ha-1, respectively). After a 175-d lag period for all treatments, the rate of pyrene removal followed first-order kinetics. The first-order rate constant was significantly higher in nonvegetated (0.098 d-1) than vegetated treatments (0.034 d-1). These data suggest that the presence of easily biodegradable organic matter from plant roots slowed the removal rate of pyrene. The levels of available P did not affect the rate of pyrene dissipation. Pyrene decreased below the detection limit of 6.25 mg kg-1 dry soil in all treatments after 301 d.

Interseeding legumes into grass sods increases herbage quality. Interseeding alfalfa (Medicago sativa L.) into bermudagrass [Cynodon dactylon (L.) Pers.] has given yields comparable to grass fertilized with high rates of N. Our objective was to compare forage quality attributes of N‐fertilized bermudagrass with alfalfa‐bermudagrass mixtures. N rates of 0, 112, 224, and 448 kg ha−1 were applied to bermudagrass monoculture and to alfalfa interseeded into bermudagrass at 20‐, 40‐, and 60‐cm row spacings. Experiments were conducted on a Cecil sandy clay loam (clayey, kaolinitic, thermic Typic Kanhapludult) and a Norfolk sandy loam (fine‐loamy, siliceous, thermic Typic Kandiudult) site. Hand‐harvested herbage samples were separated into botanical components. Crude protein, acid‐detergent fiber and neutral‐detergent fiber were measured using a combination of wet‐lab and near infrared reflectance spectroscopy (NIRS) procedures. Nitrogen increased the crude protein in bermudagrass monoculture by 11 to 61 g kg−1. The crude protein response of bermudagrass in mixtures to N was slight to nonsignificant. Increasing row spacing of alfalfa reduced grass crude protein by 9 to 23 g kg−1 and had no effect on alfalfa crude protein. Fiber fractions decreased slightly in grass with added N, but fiber in alfalfa was not influenced by any treatment. Yield of crude protein increased with N, particularly in bermudagrass monoculture, but interseeding alfalfa without N produced crude protein yields that usually exceeded those of bermudagrass monoculture at the 448 kg ha−1 N rate. Interseeded alfalfa, even at wide row spacings, appears to produce enough biological N to replace 448 kg fertilizer N ha− or more in the production of herbage protein in bermudagrass.