Fly Densities on Cattle Grazing ‘WW-B.Dahl’ Old World Bluestem Pasture Systems

Krishna B. Bhandari, Charles P. West, Scott D. Longing


The decline in water supply for irrigation in the Texas High Plains is encouraging transition to drought-tolerant forages such as ‘WW-B.Dahl’ old world bluestem [OWB, Bothriochloa bladhii (Retz) S.T. Blake]. Cattle (Bos taurus L.) grazing this grass have been casually observed to host fewer horn flies (Haematobia irritans L.) ­but definitive data are lacking. Visual ratings (1-5 scale) were contrasted for fly densities on steers grazing two forage systems: grass-only (predominantly OWB) vs. grass-legume (OWB and alfalfa, Medicago sativa L.) in 2015 and 2016. Mean fly densities were not different between the systems in either year, but a date × system interaction in 2016 (P = 0.052) suggested a lower fly density for grass-only on 23 June. Horn fly densities were not consistently reduced on cattle grazing the OWB-dominant grass-only system, therefore our observations do not support anecdotal reports of significant deterrence of horn flies by WW-B.Dahl OWB.


alfalfa, cattle, horn flies, old world bluestem

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