Undervine management

Introduction

There are two main approaches to managing the area under the vine row: 

• reducing undervine growth 
• maintaining groundcover

Growth can be reduced through a range of options including herbicide, cultivation, mowing or mulch. Groundcovers can include both native and introduced, and annual and perennial species. 

Why undervine management matters

Reducing undervine growth and maintaining groundcover have the following advantages:

“It is less about what the vineyards look like, and more about how they are functioning.” Andrew Butler, Viticulturalist

There is no one right answer

There's no single strategy that works for every vineyard. The right answer depends on many factors, and it won't be the same for everyone.

For example, two recent Wine Australia studies, in different regions and different seasons, gave quite different results:

Options to reduce undervine growth

Where growers choose to reduce undervine growth, there are four main options: 

• Herbicide: These are fast and effective but frequent use can increase the risk of herbicide resistance, affect soil microbial health and leave bare soil that is more prone to crusting, runoff and erosion. Herbicide use is restricted later in the season and regulatory changes are narrowing the herbicide options available, particularly with the phase-out of paraquat and diquat in vineyards by June 2028. At the same time, there's also a growing customer preference for reduced chemical inputs. 
• Cultivation: This removes weeds without chemicals but disturbs soil structure, promotes water evaporation and carbon release, and can increase erosion. Cultivation can also be expensive given initial equipment purchases, trellis modification costs, high diesel use and the time taken, as it typically requires more passes than herbicide.
• Mulching: This has the potential to provide multi-year weed suppression and build soil organic matter, but can be expensive, raises both frost and fire risk, can harbour pests like snails and introduce weed seeds if mulch isn’t clean.
• Mowing: This minimises soil disturbance, keeps growth out of the canopy and temporarily reduces competition with vines for nutrients and water, but requires multiple passes per season.

For more detailed information on each of these options, explore the AWRI's chemical weed control and non-chemical weed management webpages for resources, case studies, webinars and research papers on undervine weed management.

Maintaining groundcover: the right undervine species

Groundcovers are plants deliberately grown in the vineyard, including native species, introduced cover crops, and both annual and perennial species. These present an emerging range of options for growers looking outside of traditional undervine management strategies.

Undervine groundcovers are increasingly being used and studied as a strategy to manage weeds. 

A Charles Sturt University study found the right species can host beneficial insects that predate on light brown apple moth. The project produced a fact sheet presenting three of the most promising groundcovers for different situations. The introduced species alyssum and native species creeping boobialla both reduced botrytis and light-brown apple moth (LBAM) damage while growing to a low height that is likely to improve airflow compared to weeds. Read the Functional biodiversity solutions for Australian vineyards fact sheet (PDF).

Choosing the right option for your site

There is no one-size-fits-all approach to undervine weed management. Growers should tailor the choice of undervine management to their site and conditions, noting that the best approach may differ in a wet and dry year. The most effective strategy may be to use a combination of different approaches.

Agronomists may be a valuable resource in assessing the following factors when making choices:

• Region and climate 
  • How water-limited is the vineyard this season? Mulching or bare earth will reduce competition for water.
  • How likely is frost? A bare or mown surface will reduce frost risk.
  • What is the degree of heat risk? Mulching or groundcovers can reduce soil temperature in heatwaves.
• Soils
  • How much microbial activity is in the soil? Herbicides and cultivation can negatively affect soil microbial health while groundcover and mulch can promote microbial activity.
  • What is the risk of erosion? Bare earth and cultivation in particular can increase the risk of soil erosion.
  • How compact is the soil? Groundcover may help reduce compaction.
• Pest and disease pressure
  • How much risk is there of insect or pest damage? Certain groundcover species can be a host to pest species such as LBAM, snails, weevils and mealybugs, while other species can reduce losses by hosting a range of beneficial insects.
• Economics
  • What is the target output for my vineyard? Does it make economic sense to invest in a labour-intensive undervine cover crop program given the market price of grapes in my region? Do I need to minimise tractor passes to save money?
  • How much does water cost? If water costs are high or supply is limited, the cost of mulch may be offset by the water savings. If water costs are lower the benefits of groundcover may easily offset the risk of competition.
  • What is the cost of each option for your vineyard? Costs vary by region, scale and contractor rates.
• Operational capacity
  • What equipment and labour are available? Some options may require more labour or equipment but may have fewer direct costs.
  • What skills does the team have? A team with more experience in growing crops may be more interested in groundcover options, while a team more experienced in spray programs and equipment-based management may prefer herbicide or mechanical options.
• Weed species
  • Which weed species are present and how do they spread (e.g. by seed, underground stems or creeping runners)?
  • Are annual or perennial weeds the main problem? Perennial weeds often require different management strategies. 
  • When do the target weeds emerge, flower and set seed? Timing control before seed set reduces future weed pressure. 
  • Are there herbicide-resistant weeds present? Alternative or integrated management approaches may be needed.