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| Cover Crops in Vines | AG1195 |
Rosie Hannah, Mildura
November 2004 |  |
A cover crop can be defined as any plant species, used singly or in a mixture, which is deliberately sown between vine rows.
The main benefits of cover crops
- Improved soil structure. The soil is more open and friable due to the addition of organic matter. The soil is easier to work - it is not as boggy when wet, nor as hard when dry. Vine roots are able to penetrate more deeply, so the plant is able to explore more of the soil for water and nutrients.
- 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. Consider the ease of growing the crop, the costs, and the benefits of the particular cover crop when choosing which cover crop to use.
Properly managed legumes set seed for future years. The introduction of the spotted alfalfa aphid and the blue-green aphid has 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.
Cereal crops are easier to establish and are less prone to insect attack than medics. Oats are the most common cereal used. However, barley gives greater early growth though less winter production, and is suitable if planted early.
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.
- Seed bed preparation. A well-prepared seedbed is required to optimise seedling establishment. It is recommended that a flat, uniform and firm soil surface exist so that seed can be placed accurately and consistently at the desired depth. Keep tillage to a minimum. Control weeds prior to seeding permanent annual regenerating swards. Broadcast seed should be spread on a loose soil surface and lightly incorporated.
- Fertiliser. Apply fertilisers at the recommended rates at optimum times to ensure good sward vigour.
- Seeding depth. Desired depth of seed burial 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. A loss of seedlings may result if seed is sown too shallow or left on the soil surface, and soil moisture is limited.
- Control of insect pests. Some cover crops, particularly 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 dry sow until the end of April. Where irrigation of the mid row is possible, green manure crops benefit from earlier establishment in March.
- Seed quality. 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. Regular slashing in winter makes conditions more comfortable during pruning, makes the cover crop more productive, and avoids the problems of working-in bulky plant material in spring. The early irrigation and frost control can be difficult unless this bulky material has time to break down.
Slash cereals and medics when they are 150mm to 200mm high. If cereals are left any later, there is greater chance that regrowth after slashing will not be as good.
Caution
Cover crops provide many potential benefits. However, this is potential for some cover crops to host pests and diseases such as Light Brown Apple Moth or phytoplasmas which are associated with Grapevine Yellows diseases (eg. AGY).
Refer to the “Organic Farming: Vineyard Weed Management” agnote for more environmentally friendly options.
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication 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.
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