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Cover crops in vines

A cover crop can be defined as any plant species, used singly or in a mixture, which is deliberately sown between vine rows to improve the management of the vineyard.

 

The main benefits of cover crops

  • Improved soil structure through increased stability, biopores and organic matter.
  • Improved trafficability.
  • Improved pest management and vine nutrition.
  • Reduced tillage.
  • Protection of soil from water and wind erosion.
  • Attraction of beneficial insects, spiders and soil borne organisms.
  • Potential reduction/suppression of some pests.
  • Reduced weed population.

 

Legumes or cereals?

Cereals and legumes are the two main categories of plants used for cover crops. When choosing which cover crop to use, consider the ease of growing the crop, the costs, and the expected benefits. Cereals and grasses have an extensive, fibrous root system that adds more organic matter and biopores (soil pores created by roots) than legumes. Cereal crops are easier to establish and are less prone to insect attack than medics. Oats are the most common cereal used although barley gives greater early growth though less winter production. Spotted alfalfa aphid and the blue-green aphid have resulted in serious damage to Harbinger and Cyprus medics. At present, snail medic is the only variety resistant of both of these aphids. It produces adequate growth, recovers well after slashing and flowers and sets seed earlier than other legumes.

 

Establishment

  • Failures in the establishment of cover crops are rarely the fault of the crops, but are normally due to not enough care taken at sowing.
  • A well-prepared seedbed is required to optimise seedling establishment. The soil surface should be smooth and firm so that seed can be placed accurately at the desired depth. Keep tillage to a minimum by using a direct-drill seeder. Control weeds prior to seeding permanent annual regenerating swards. Broadcast seed should be spread on a loose soil surface and lightly incorporated with harrows.
  • Apply fertilisers at the recommended rates at optimum times to ensure good sward vigour.
  • Seeding depth. Desired depth of sowing is related to seed size. Small seeds (clovers, medics and grasses) must not be sown deeper than 15mm while larger seeds (cereals, beans and peas) should be sown at 20-30mm. Poor emergence will result if seed sown too deep or if the seedbed dries out when seed is sown too shallow or left on the soil surface.
  • Control of insect pests. Legumes are very susceptible to damage by insect pests such as red-legged earthmite and lucerne flea. Monitor for damage and control using appropriate insecticides at optimum times.
  • Seeding time. Establish green manure crop as early as practical in autumn. Do not sow into dry soil until wet weather is predicted at the end of April. Where irrigation of the mid row is possible, cover crops benefit from earlier establishment in March.
  • Always use seed of high quality.

 

Insect pests

Snail medic has good tolerance to the spotted alfalfa and the blue-green aphid but establishment of seedlings may depend on spraying with insecticide if aphid numbers are high. Control of the red-legged earthmite is important right from the stage when the medic emerges. Insecticides are available for treating the seed before sowing, or the crop itself. Later sprays may be needed during winter.

 

Cover crop management

Cover crops should be managed like a pasture. Slashing the cover crop and delivering the clippings on the vine line provides a cheap and effective mulch to reduce water loss, add organic matter and keep the soil cool in summer. Slash the cover crop close to the ground in late winter or early spring to minimise the frost risk.

 

Caution

Cover crops provide many benefits but some cover crops are hosts to pests and diseases such as Light Brown Apple Moth or phytoplasmas which are associated with Grapevine Yellows diseases (e.g. AGY).

 

Further information

Refer to the “Organic Farming: Vineyard Weed Management” Agnote for more environmentally friendly options. For information relating to the safe and appropriate use of chemicals, including management of chemical residues and licensing requirements, call Agriculture Victoria Customer Service Centre of 138 186 and ask to speak to your local chemical standards officer.

 

The advice provided is intended as a source of information only. Always read the label before using any of the products mentioned. The VVBC does not guarantee that the information is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.