COVER CROPS in South African Vineyards

CHAPTER 9 PESTS

compared plots with a grazing-vetch, triticale, or dwarf fescue cover crop to a control with no cover crop. Pugnacious ants were more common on the ground in the triticale treatment, but this did not translate into higher numbers of either ants or mealy bugs in the grapevines.The authors concluded that none of the cover- crop treatments in this trial were associated with either higher or lower numbers of pugnacious ants or mealy bugs in the grapevines. Other ant species were not investigated in this trial. Reference list Addison P and Samways MJ. 2006. Surrogate habitats demonstrate the invasion potential of the African pugnacious ant. Biodiversity and Conservation , 15, 411–428. Addison P, Samways MJ and Fourie J. 2007.The effect of cover crops on ants and mealy-bugs in vineyards. Wineland Technical Yearbook 2007 , 46–48. Nematodes Coastal region A trial was conducted in a drip-irrigated vineyard of Shiraz grafted onto 101-14 at Blaauwklippen near Stellenbosch. The study looked at the effect of cover crops with biofumigation properties on ring-nematode populations. Pallinup oats, Braco white mustard, Jade canola, Caliente 199, and Nemat were compared to two treatments without cover crops, one with and one without nematicide application. Two management strategies were applied to the work rows at grapevine bud-break for all treatments. In the first, full-surface chemical control was applied, and dry matter of weeds and cover crops was left standing. In the second, weeds and cover crops were slashed, and the residue mechanically incorporated into the soil. Chemical weed control was applied in the vine row. Numbers of ring nematodes in the vine and work rows were counted four times each year: in April, before cover crops were sown; at grapevine bud- break, before management practices were applied; and 15 and 60 days after management practices were applied.As the ring-nematode populations in the work rows were insignificant, these are not discussed further.

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