herbicides, chemicals applied to vineyards to control the growth of weeds. They may be either pre-emergent (or residual) or post-emergent (knockdown). The latter group comprises two types, contact and systemic herbicides. Residual herbicides act against germinating seedlings of the weeds, while post-emergent herbicides damage growing weeds. Typically, herbicides are applied only to the strip of ground directly under the vine, and weeds growing between the rows are controlled by cultivation or mowing. Herbicides are used even between rows in some vineyard regions, though there can be risks of soil erosion or loss of water infiltration without the organic matter produced by cover crops in this zone.