Roundup Use in Autumn

Perennial Weed Control

Roundup can be used in the stubbles of all crops to control annual and perennial weeds.

Common Couch

• For long-term control of Couch it is essential not to cultivate or disturb rhizomes after harvest. Broken rhizomes can be buried and lie dormant, missing the spray altogether

• Take a fork and dig up rhizomes to decide when spraying should commence. Too often couch is sprayed in September when growth is from the old mother shoot attached to 1-2m of new rhizome leading to poor results.

• Wait until new rhizomes have come to the surface and produced shoots with 2-3 leaves.

• Optimum timing is usually late September through October, but spraying can continue until December if Couch is growing, green and healthy.

Onion Couch

Spray Onion Couch at the end of September/ early October when all the bulbils have broken dormancy and produced leaf growth. This means not just shoots on the top 2 bulbils, but shoots from lower down the chain too, as glyphosate will not translocate between bulbils. Where the split dose is being applied, half may be applied in the stubbles. The annual rate should be sufficient for seedlings. Ensure the selective weed control programme applied in crop controls any seedlings, otherwise the infestation will re-emerge.

Volunteer Potatoes

Spray onto at least 6 inches of new growth, from mid September through October, but at least 7 days before the first frost. (Frost will damage the leaves and reduce translocation to the tubers). Leave a minimum of 7 days after spraying before cultivation.

Annual Weed Control

Roundup can be used to control annual weed seedlings on ploughed or cultivated land, on stale seedbeds and also after planting but before crop emergence.

The technique of creating stale seed-beds is a vital tool in out-of crop control of difficult annual grasses. Stale seedbeds are an integral part of reduced tillage systems.

To encourage the maximum amount of weed germination before drilling and to create a stale seedbed prior to planting spring crops:

1. Create a medium quality, 5cm clod size, seedbed using a tined cultivator on light soils and heavy disc harrows on medium/heavy soil.

2. Work top down to conserve moisture. Consolidate with a disc ring press, Cambridge Roll or double disc ring press, depending on soil type.

3. Wait for weed germination, 10-20 days.

4. Spray weeds with Roundup.

5. 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

All Roundup formulations have approval to spray after drilling but before crop emergence. They have been developed to allow tank mixing with residual herbicides to control any weeds surviving the cultivation and drilling operations. Be cautious when using this tank mix, if crop germination has begun then do not include Roundup. The safest option is to only use Roundup tank-mixes within 48 hours drilling. If there is a greater delay, check fields carefully for any sign of germination before making an application. In general, germination occurs sooner in early autumn when seedbeds are warmer so be particularly cautious at earlier drilling dates.

Cautions: Always look at our Tank Mix sheets to check before mixing any Roundup formulation

ETA formulations of glyphosate do not mix easily with any other pesticide