Autumn is the time for cover crops and weed control
By Brandy Rawnsley
Cover crops need moisture for germination and establishment, so autumn is the best time to get them in the ground.
Planting cover crops between vine rows can have many benefits. They improve soil structure (especially after a season of compaction from traffic), increase organic matter, improve water infiltration and drainage, reduce erosion and suppress weeds.
Cover crops provide ease of access to the vineyard particularly in wet conditions to assist operations such as harvest, pruning and spraying.
Additionally, cover crops create biodiversity in the vineyard and a favourable environment to support beneficial insects, pest predators and soil biology.
Cover crops can have a high demand for water and compete with your vines for nutrients. But this can be mitigated by correct species selection and appropriate management of cover crops. On the upside, cover crops can be used to control vine vigour and use of legumes can add nitrogen to the system. If frost may be an issue, close mowing in early spring alleviates the cooling effect of cover crops.
The choice of cover crop depends on rainfall in your region, soil type and which seed can be readily obtained. There is a wide selection of cereals, legumes, blends, brassicas, medics, clovers, grasses and natives to suit your soil type and management needs.
There are many publications and resources online, including Wine Australia’s Cover Crop Finder to aid the selection of cover crops suitable for use in Australian vineyards.
You should be aware of the nutrient requirements for the cover crop. It’s recommended to conduct a soil analysis to ensure the nutrient status of the soil is adequate for healthy growth of cover crops and vines. Where necessary, the application of pre-plant fertilisers can improve the soil nutrient status and aid in crop establishment.
Weed control is critical to successful cover crop establishment. Cover crops should be sown into soil that is free of actively growing weeds.
Prior to sowing, you should consider using a knockdown herbicide spray for existing weeds, or a pre-emergent herbicide to stop weed seeds from germinating. The range of herbicides permitted for use in viticulture in Australia is restricted, so refer the AWRI’s Dog Book to select the right product to spray.
With careful planning and preparation of your mid row, you’ll reap the rewards of putting in a cover crop this autumn.
Dr Belinda (Brandy) Rawnsley is a Syngenta Technical Services Lead for Viticulture and Horticulture