Impact of Mowing Height and Nitrogen Fertility on Crabgrass Cover in ‘RTF' Tall Fescue1

Tall fescue (Festuca arundinacea Shreb.) has exceptional utility as a low maintenance lawn in the transition zone. However, during the summer smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.] infestations can reduce the aesthetic value and function of the turf and lead to a thinning of the tall fescue stand, noticeable after the crabgrass plants have senesced. Research was conducted to evaluate the impact of mowing height and nitrogen fertility on smooth crabgrass plant counts and tall fescue cover in Virginia Beach, VA. Plots were mowed at either 6 cm (2.5 in) or 10 cm (4 in) and received 49, 171, or 220 kg of nitrogen annually per hectare (44, 152, and 196 lb.A−1). Mowing at 10 cm with the highest level of fertility resulted in the most turfgrass cover among all the treatment combinations. Mowing at 10 cm as opposed to 6 cm resulted in less smooth crabgrass plants, regardless of nitrogen fertilization rate. Index words: fertilization, turfgrass, weed control. Species used in this study: Smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.]; tall fescue [Festuca arundinacea Shreb. synonym Schedonorus phoenix (Scop.) Holub].

Yield and nutritive value of irrigated tall fescue compared with orchardgrass: In monocultures or mixed with alfalfa

Thompson, D. J. 2013. Yield and nutritive value of irrigated tall fescue compared with orchardgrass: in monocultures or mixed with alfalfa. Can. J. Plant Sci. 93: 799–807. Orchardgrass (Dactylis glomerata L.) is commonly grown for irrigated forage production in interior British Columbia. Tall fescue [Schedonorus phoenix (Schop.) Holub.] is also adapted to the area but no comparative trials have been reported. Three varieties of each grass species were grown in monocultures or in mixtures with alfalfa at three irrigated sites throughout southern interior British Columbia. Study objectives included comparing the forage yield and nutritive value of the following groups: (1) tall fescue and orchardgrass monocultures, (2) tall fescue and orchardgrass mixtures with alfalfa and (3) grass-alfalfa mixtures with monocultures. In monoculture, tall fescue yield was 9% greater than orchardgrass (significantly greater yield at 3 of 6 site-years), though forage nutritive values were similar. Mixtures of the two grasses with alfalfa had similar yields, but those containing tall fescue had superior nutritive value. Alfalfa contributed a greater percentage to total yield and had higher survival when mixed with tall fescue. Tall fescue is a viable alternative to orchardgrass for irrigated forage production in monoculture and may be more suitable for mixtures with alfalfa. Our findings demonstrate a functional diversity effect; grass-alfalfa mixtures over-yielded the mean of the alfalfa, orchardgrass, and tall fescue monocultures by 12%.

Evaluation of Cattle Grazing Distribution in Response to Weed and Legume Removal in Mixed Tall Fescue (Schedonorus phoenix) and Legume Pastures

Grazing experiments were conducted during 2009 and 2010 to investigate the effect of herbicide application and subsequent weed removal on cattle grazing distribution in mixed tall fescue and legume pastures. At each location, herbicide applications were made to one-half of the grazed hectares to remove existing weeds and brush. Weeds and legumes were left nontreated across the remaining half of the grazed hectares at each location. Global positioning system tracking collars were fitted to three beef cows at each site and coordinates from each collar were recorded at 1-h intervals for 3 to 4 mo after herbicide application. At each location, broadleaf weeds were reduced from 1 to 51 kg ha−1, and legumes were completely eliminated in herbicide-treated compared to nontreated portions of the pastures. By the end of the season, the forage grass and legume component of pastures was greater and weed component lower in treated compared to nontreated portions of the pastures. By 3 mo after treatment, the cattle distribution was 1.3 to 5 times greater in herbicide-treated compared to nontreated portions of pastures. Overall, results from these experiments indicate herbicide treatment can increase desirable forage mass and thus modify cattle grazing distribution in pastures.

Native and Exotic Grass Competition with Invasive Hoary Cress (Cardaria draba)

The Eurasian perennial mustard, hoary cress, Cardaria draba (Brassicaceae), is an invasive weed in western North America that can displace native plants and other desirable forage species in pastures and rangelands. This study investigated the competitive ability of 11 grasses representing nine species in the genera Festuca and Poa from either North America (NA) or Europe (EU) against hoary cress. Hoary cress was grown alone and with four different grass densities under controlled conditions with ample water and nutrient supply, typical for riparian and disturbed habitats, in which hoary cress infestations are commonly found. Of the five Festuca grasses tested, only Schedonorus phoenix (= F. arundinacea) decreased hoary cress biomass. Four of the six Poa grasses tested decreased hoary cress biomass and were ranked by decreasing competitive effects as follows: P. annua > P. compressa (EU) > P. pratensis (EU) > P. compressa (NA). The most competitive grass species also experienced higher intraspecific competition. Within both grass genera, Eurasian species were more competitive against hoary cress than their North American congeners, which suggests that hoary cress establishment may be facilitated by lower biotic resistance in the invaded range. Regardless of origin, sod-forming Poa species were competitive at low densities, while Festuca species only had significant effects at high densities if at all. Based on our results we recommend the use of Poa species for restoration of riparian and disturbed sites following the control of hoary cress infestations to restrict recolonization.

Tolerance of Turf-type Tall Fescue Established from Seed to Postemergence Applications of Mesotrione and Quinclorac

Research was conducted to evaluate the tolerance of tall fescue to mesotrione applied during establishment from seed. Nine field studies were conducted over a 3-year period (2004–2006) near Knoxville, Tenn., to evaluate the tolerance of seedling tall fescue [Schedonorus phoenix (Scop.) Holub] to mesotrione and quinclorac. The first evaluated tall fescue tolerance to single and sequential applications of mesotrione compared with quinclorac (multiple application study). The second evaluated the timing of mesotrione application on tall fescue injury and establishment (timing study). In the multiple application study, all treatments injured tall fescue 23% or less. Quinclorac reduced tall fescue groundcover up to 17% 63 days after emergence (DAE). Mesotrione at 0.28 kg·ha−1 applied 28 and 42 DAE or 14, 28, and 42 DAE decreased groundcover only 4% and 6% 63 DAE. In the timing study, mesotrione at 0.28 kg·ha−1 applied at 7 and 28 DAE injured tall fescue 17% to 21% 7 and 14 days after application; however, injury subsided to less than 10% by 28 days after application. Only mesotrione at 0.28 kg·ha−1 applied 7 DAE resulted in delayed tall fescue groundcover at 70 DAE. Variation was observed in Fall 2005 evaluations compared with other evaluations, which may be attributable to delayed seeding date and cool, wet conditions.