COVER CROPS in South African Vineyards

COVER CROPS IN SOUTH AFRICAN VINEYARDS

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600 -400 2009/2010 2010/2011 2011/2012 2012/2013 4-year average Change in nematode count per 250 centimetre 3 of soil 400 200 0 -200

Pallinup oats Chemical Braco white mustard Chemical Braco white mustard Mechanical Nemat Chemical No cover crop Chemical Nematicide Chemical Average change in nematode count for all treatments

FIGURE 9 .7. Change in nematode counts in the vine row during the period from 60 days after bud-break to the following April in selected treatments. Chemical: full-surface chemical control at bud-break and dry matter left standing. Mechanical: cover crops and weeds slashed and mechanically incorporated into soil of work row. Adapted from Fourie et al (2016). In summer, nematode numbers increased more in all cover-crop treatments where mechanical cultivation was practiced than in treatments where full- surface chemical control was applied.This was also true for the nematicide treatments, but not for the treatments where no cover crop was planted and no nematicide applied. Therefore, when mechanical cultivation was applied, nematode numbers initially dropped more than when chemical control was applied, but subsequently also increased more. In conclusion, cover crops were not able to achieve effective suppression of ring nematodes in this trial.The significant increase in ring nematodes during the summer and late autumn indicate that chemical control with a nematicide

later in the season is necessary. Lower Orange River region

A study by Addison and Fourie (2008) looked at plant-parasitic nematodes in Sultanina grown on own roots in Keimoes. They compared nematode prevalence in one perennial and eight annual cover crops to a control with no cover crop.

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