Mixed Stocking by Cattle and Goats for Blackberry Control in Rhizoma Peanut–Grass Pastures

Abstract

Blackberry (Rubus fruticosas L.) can be a weed in rhizoma peanut (Arachis glabrata Benth.)–grass pastures. Goats (Capra hircus) have provided effective control of Rubus spp. in other environments, but their efficacy has not been tested in legume‐grass swards in this context. The objective was to evaluate rotational stocking by goats alone or with cattle (Bos spp.) for blackberry control. Treatments stocked at 2.6 animal units (AU) ha−1 included a cattle‐alone control, goats alone, concurrent stocking of cattle and goats, sequential stocking of cattle followed by goats, and sequential stocking of goats followed by cattle. The final treatment was concurrent stocking at a stocking rate of 3.5 AU ha−1. Goats grazed blackberry readily, but cattle avoided it. Blackberry selection was greatest when goats followed cattle sequentially. The blackberry proportion of total biomass increased 10% when cattle grazed alone but was reduced 11% with goats alone and 13% with mixed concurrent grazing at a high stocking rate. Treatments including goats resulted in reductions or smaller increases in blackberry mass than for cattle alone. Goats alone or with cattle resulted in greater removal of blackberry leaf and in reduced height and stem density than cattle alone. Goats reduced the blackberry contribution more than cattle, but it was not eliminated from initially heavily infested pastures across 2 yr of grazing. A greater goat stocking rate or a combination of grazing and mowing may be needed for complete eradication.

Blackberry Regrowth and Persistence Responses to Defoliation in Mixed Rhizoma Peanut‐Grass Swards

“…These data provide rationale to explain the conclusion of Krueger et al (2014) that grazing alone is not sufficient to eradicate blackberry. Goats browsing blackberry selected leaf primarily and did not reduce blackberry height greatly (Krueger et al, 2014).…”

“…These data demonstrate the potential of blackberry to spread in rhizoma peanut‐grass pastures if not aggressively defoliated. Relating these results to a pasture situation, because animals browsing blackberry may reduce its height only slightly (Krueger et al, 2014), achieving near complete removal of leaf through browsing is likely required to negatively impact blackberry stands by browsing alone. Combining browsing for leaf removal with periodic mechanical mowing to a short stubble height (∼8 cm) appears to be a more successful strategy to reduce blackberry DM accumulation, cover, and stem density in mixed rhizoma peanut‐grass pastures.…”

“…Browsing or grazing of blackberry has been viewed as a potential control option (Amor, 1974a; Ainsworth and Mahr, 2005; Ingham, 2014; Krueger et al, 2014). In a pilot study, Dellow et al (1987) noted partial control of blackberry browsed by goats ( Capra hircus ).…”

“…In a companion grazing study conducted in a blackberry-infested, mixed rhizoma peanut-grass pasture, cattle avoided grazing blackberry almost totally, while approximately 50 to 60% of bites taken by goats were of blackberry (Krueger et al, 2014). Because there was opportunity in that study for goats to consume legume, grass, and blackberry plant components, there was relatively little direct control over the height to which blackberry was browsed or the extent to which blackberry leaf was removed.…”

Challenges, Opportunities, and Applications of Grazing Research

“…Specific recommendations for future research were derived from a synthesis of the US pastureland literature (Sollenberger et al, 2012). Examples of these knowledge gaps include (i) thresholds for grazing intensity above which substantial environmental impacts (e.g., sediment and nutrient runoff ) occur; (ii) effects of winter feeding on pastureland on surface and subsurface waters (Owens et al, 1997); (iii) management practices that benefit the broad array of wildlife present in an ecosystem (Frisini and Mariani, 1995); (iv) timing of grazing and of livestock exclusion in riparian areas; (v) the effect of pasture or paddock size and shade and water distribution in the landscape on livestock distribution, nutrient redistribution, and efficiency of nutrient recovery from livestock excreta (Mathews et al, 2011;Dubeux et al, 2014); (vi) the role of cograzing or sequential grazing by different animal species as a prescribed grazing tool for maintaining legumes in pastures or ridding swards of invasive, unwanted, or potentially toxic plants (Krueger et al, 2014); and (vii) use of legumes to reduce the C footprint of N-fertilized grass systems and ameliorate the impact of climate change ( Jensen et al, 2012).…”