With increasing problems of resistance to conventional herbicides in Black-grass, Wild-oats and Rye-grass it is vital to control these weeds outside the crop as part of integrated weed management.
All spring-sown crops benefit from a clean start. Cultivating weeds prior to sowing is unsatisfactory, as trials have shown that weed control is frequently below 50%, and many weeds re-grow in the crop. Furthermore, ploughing and cultivation need to be carried out when soil and weather conditions are correct in order to avoid over-cultivation and to protect the soil structure while minimising soil moisture loss. An alternative is to control emerged weeds with Roundup, to reduce establishment costs and ensure a clean start.
Uncultivated land can harbour plants with a large variation in size which must be treated with the appropriate dose of Roundup according to that size.
NB. Land in some SPS Environmental Schemes cannot be sprayed until 15th February. Some weed species, especially perennials, will not be at their most susceptible stage in spring.
The technique of creating stale seedbeds is a vital tool in out-of-crop control of difficult annual grasses. Stale seedbeds are an integral part of reduced tillage systems. The Soil Management Initiative produces useful literature.
To encourage the maximum amount of weed germination before drilling and to create a stale seedbed prior to planting spring crops:
- Create a medium quality, 5cm clod size, seedbed using a tined cultivator on light soils and heavy disc harrows on medium/heavy soil
- Work top down to conserve moisture. Consolidate with a disc ring press, Cambridge Roll or double disc ring press, depending on soil type
- Wait for weed germination, 10-20 days
- Spray weeds with Roundup
- Drill as early as 6 - 48 hours later depending on the formulation used
The use of stale seedbeds in conjunction with reduced tillage techniques means that savings in time, labour and cost can be achieved compared to conventional ploughing techniques. Yield increases can be common following the reduced tillage, stale seedbed technique.
Caution: Carrying out reduced tillage techniques without the use of stale seedbeds can result in an increase in annual weed seeds and problems for weed control throughout the rotation.
Post plant, pre-emergence
Where spring crops are established under time constraints, there are often situations where the crop is drilled, but some green material is left on the surface. This can grow away again and present a real challenge for post-emergence herbicides.
All Roundup formulations have recommendations to spray before crop emergence. This allows residual herbicides to be tank-mixed with Roundup in order to combine residual weed control programmes with the removal of any weeds surviving the cultivation and drilling operations.
Modern Roundup formulations have been developed with improved physical properties, leading to increasingly good compatibility with other herbicides, easier use and quicker cleaning of packaging and equipment.
Cautions: Always consult the Tank Mix Guide to check before mixing any Roundup formulation or contact the Technical Hotline on 01954 717575
ETA formulations of glyphosate do not mix easily with any other pesticide