Under-vine management - Herbicides

The main reason for managing the under-vine area is to reduce weeds, which take important water and nutrients from the vines. This is especially important in times of drought. Most growers spray herbicides, but there are other options.

Herbicides
Herbicides are a relatively inexpensive option and have the advantage of keeping the soil structure intact. Generally, a strip of broad-spectrum herbicide is periodically sprayed under the vines to about 0.5-0.75 m on either side of the vine row. Weeds should be sprayed before they seed to reduce the seed bank.

Take special care if systemic herbicides such as glyphosate (Roundup) are used during the growing season, as they may damage the vines. Remove all suckers and spray only in very calm conditions using a spray guard to prevent drift. Glyphosate is safe to spray in the vine dormant season, but only effective when weeds are actively growing.

Non-systemic herbicides such as Spray.Seed (paraquat + diquat) or Basta (glufosinate-ammonium) are safer for grape vines during the growing season. Be aware though that Spray.Seed is poisonous and special care is needed in handling and spraying operations.
If particular weeds are a problem, other options include Amitrole (amitrole + ammonium thioscyanate) and Illico (amitrole + glyphosate + ammonium thioscyanate). Additives such as Hammer (cafentrazone-ethyl) can also improve the effectiveness of knockdown herbicides against weed species that are harder to kill, like marshmallow and woody weeds. Pre-emergent or residual herbicides such as simazine and diuron are another option to provide longer-term weed control. However, these are not recommended for sandy soils, like those in the Granite Belt, where they may damage vines.

To reduce the possibility of herbicide resistance, it is a good idea to alternate between herbicides with different activity groups or to rotate herbicides with alternative methods of weed control. A list of herbicides registered for use in vineyards, can be downloaded from the Australian Wine Research Institute. Always read labels carefully before using any herbicide or other chemical product.