Introduction
Many tools now exist to manage the undervine strip mechanically, and without resorting to herbicides, and these all have their advantages and disadvantages.
An intervine plough that turns the soil may be the most effective in removing weed roots, but will cause the most damage to soil biology.
Tools that cut weed roots without inverting the soil will do less damage to the soil biology, but care needs to be taken to balance the frequency of use to minimize disturbance.
Tractor-mounted strimmers and rotating discs of rubber ‘fingers’ may achieve what you need without disturbing the soil at all.
In detail
The undervine area is more challenging to manage without tillage than the interrow.
In some vineyard contexts, carefully selected cover crops are very successfully used under vine to control weed growth. However, in some contexts there are common concerns and research evidence that plants growing undervine can detrimentally compete with the vine for soil water and nutrients. Yield may be compromised, especially in the early years when vines are young and haven’t established deeper root systems.
Vineyard context is key to deciding the best solution for managing the undervine area, whether that is strimming/mowing/grazing animals, cultivation of some sort, plant suppressants (mulch, fleece etc) or careful species selection.
When using cover crops undervine, careful selection and management is required to avoid them growing up into the vine canopy causing reduced air circulation, increased humidity and support of disease development. This can also reduce access to fruit at harvest. Drip irrigation can increase growth of undervine plants, due to the location of the dripper line. Growth can be controlled by strimming, mowing and/oror the use of grazing animals
To establish cover crops undervine, one option is to sow them in the interrow, allow them to set seed and then mow and side discharge them undervine so that the seeds germinate in the following season. This has been proposed by Dr Tom Line of University of Adelaide.
Although certain location and species-specific undervine plants do not result in the above challenges, where issues commonly arise there is a need to manage the undervine area to reduce the above risk factors.