Section 4.6: Post-grafting Management of Vines – Weed Management

“Field grafting is a great way to change variety or clone and quickly return a vineyard to full productive potential. Field grafters are only partly responsible for the success or failure of field grafting. Understanding what preparation and follow-up is required as a grower to influence the final strike rate is critical. VitiSense provides all the information, techniques, demonstrations and explanations and to ensure your field grafting experience is a positive one”.

 As mentioned earlier, a “clean” undervine will reduce the potential for chewing insects to damage grafted shoots. Keeping undervine weeds under control is important so they do not negatively impact on the growth of grafted shoots. This can occur when trunks can be obscured by tall weeds, especially grasses which can make taping more difficult. Grafted shoots can grab hold of tall weeds with tendrils which makes training shoots more difficult and risks damaging the grafted shoots. Creeping grasses such as couch and kikuyu can reduce the overall vigour of vines which can also reduce the success of grafting. It is advisable to establish and then maintain control these weeds prior to grafting. 

Organic weed control for grafted blocks. 

Mowing undervine is fine for grafted vineyards as long as the irrigation system can provide adequate water for vines. A green undervine can be a help in wet seasons when excess soil moisture needs to be “soaked up” which can assist in reducing excess sap flow in grafts. Undervine cultivation for weed control is also fine for grafts. Grazing livestock for weed control can be done also as long as they have vacated the vineyard as shoots emerge. A warning for sheep which can rub on grafts and dislodge buds and tape as they scratch themselves on trunks. If using “organic” herbicides, be vigilant an avoid spray drift onto grafted shoots as many are strong leaf blade desiccants which will damage and potentially kill grafted shoots. 

Chemical weed management for grafted blocks. 

Pre grafting 

If vines are dormant with no watershoot or other green shoot growth then a systemic herbicide can be safely applied according to label recommendations. A pre emergent herbicide can also be applied if there is bare soil undervine with a low amount of organic matter (trash) and seasonal rainfall is adequate to assist in effective herbicide activity. 

Post grafting 

In the first growing season of grafted shoots, it is recommended to only use non-systemic herbicides to avoid any potential off target drift onto grafted shoots. After the grafted shoots have lignified then systemic herbicides can be used from then onwards.