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Multiparous, lactating, crossbred (Simmental × Angus) beef cows with spring-born calves at side (n = 16 per year; 4 per pasture) were used each of 3 yr to evaluate supplementing modified distillers grains plus solubles mixed with low-quality forage on cow and calf performance while grazing. Cow-calf pairs were assigned randomly to treatment with 2 replications (pasture) per year for 3 yr. Treatments were (1) recommended stocking rate of 9.46 animal-unit month/ha with no supplementation (CON) or (2) double the recommended stocking rate (18.9 animal-unit month/ha) and supplemented with a 30:70 modified distillers grains plus solubles:cornstalks (DM) mixture (SUPP). To replace 50% of grazed forage DMI, SUPP pairs were fed an average of 1.13% of BW (DM) over the grazing season. Pairs grazed adjacent smooth bromegrass pastures for 130 d during the summer. Gain was not different (P= 0.19) between SUPP and CON cows (0.28 vs. 0.19 kg/d, respectively). Ending cow BW was not affected (P= 0.46) by treatment. Similarly, calf gain was not affected (P= 0.31) by supplementation. In studies where confined cow-calf pairs were fed average-quality (IVDMD = 52.9%) forage, DMI was 2.58% of pair BW. Based on these data, CON and SUPP pairs consumed 18.6 and 19.1 kg of DM, respectively, of total feed per pair daily. The SUPP pairs consumed 7.1 kg of DM/pair daily of the supplement, replacing approximately 35% of grazed forage intake. These data suggest mixtures of ethanol co-products and low-quality forages can be supplemented to replace grazed forage intake of cattle, allowing for increased stocking rate without affecting animal performance.

A 2-yr beef systems study evaluated winter and summer modified distillers grains plus solubles (MDGS) supplementation in a forage system. Treatments were arranged in a completely randomized design as a 2 × 2 factorial. Each year, 229 spayed heifers (215 ± 26 kg of BW) grazed corn residue 144 d, bromegrass 32 d (winter), and native range 120 d (summer) and were followed through the feedlot. Treatments included 0.91 kg of DM MDGS (LO) or 2.3 kg of DM MDGS (HI) supplement while grazing corn residue, and MDGS fed at 0.6% of BW daily (SUP) or no MDGS (NO SUP) during the summer. Winter ADG was 0.24 kg greater (P< 0.01) for HI than LO across both years. Summer ADG was 0.21 kg greater for SUP compared with NO SUP across both years (P< 0.01). Gains throughout the entire growing system were greatest for HI SUP, intermediate for HI NO SUP and LO SUP, and least for LO NO SUP. There were no interactions between winter and summer supplementation on ADG throughout the entire growing system (P≥ 0.12). At the end of the feedlot phase, HCW was greater (P≤ 0.03) by 23 and 15 kg (yr 1 and 2, respectively) for HI than LO. Summer SUP decreased finishing ADG by 0.21 kg (P= 0.02) in yr 1 and decreased G:F (P≤ 0.07) both years. Across both years, profit was greater for HI than LO cattle (P≤ 0.02), but summer supplementation did not affect profit (P= 0.15).

The effects of phylloplane bacteria on the conidial germination, germ tube growth, appressoria formation, and disease severity of the mycoherbicide agent Colletotrichum coccodeswere investigated. Seven isolates of fluorescent Pseudomonasspp. and two other bacterial isolates were recovered from the mature leaves of velvetleaf (Abutilon theophrasti). Co-inoculation of C. coccodeswith each of three isolates of Pseudomonasspp. significantly increased the number of lesions and disease severity caused by C. coccodeson velvetleaf seedlings in two growth chamber experiments, and also accelerated the appearance of symptoms. All bacterial isolates reduced conidial germination and germ tube branching of C. coccodesand three isolates increased the frequency of germ tubes with appressoria on cellophane membranes overlaid on leaf disks of velvetleaf. All isolates reduced conidial germination 30 h after co-inoculation with C. coccodeson detached leaves, but increased the relative frequency of dark-colored appressoria without germ tubes and decreased the total germ tube length. These results suggest that certain phylloplane bacteria may enhance the efficacy of mycoherbicides by stimulating the formation of appressoria and reducing the saprophytic preinfection mycelial growth of the pathogen on the phylloplane. This acceleration of infection may decrease the critical period of moisture required for infection in the field.

The host range of single isolates of Puccinia coronata, P. graminis, and P. reconditafrom quack grass (Agropyron repens) was determined within controlled environment conditions. The P. coronataquack grass isolate had a relatively broad host range and this rust may overwinter as mycelium in quack grass rhizomes in eastern Canada. The quack grass isolates of P. graminisand P. reconditawere specific to quack grass.

AbstractPredispersal seed predation of Cirsium arvense(L.) Scop. (Asteraceae) by Orellia ruficauda(Fabr.) (Diptera: Tephritidae) occurs in about 20–85% of the seed heads and the proportion of damaged seeds per attacked head averages 20–80% depending on geographical location and sampling date. Microscopic studies of damaged seeds were performed. Although the impact of this seed predator is not severe, it may be an important factor in the population regulation of the weed.