Certain weeds may be present in crop areas which herbicides and other management techniques cannot control well in the crop system. The stale seedbed technique can result in improved weed management in problematic areas or with problematic weed species. After soils are prepared for planting, most of the weed seeds in the upper 1" to 2" of the soil will germinate within two weeks if soil moisture and temperature are adequate. The stale seedbed approach involves preparing the soil as if for planting, without actually planting the crop. Instead, weeds are allowed, even encouraged (with irrigation or row covers), to grow. Weeds are then killed with Gramoxone, Roundup, Scythe or flaming.
Killing emerged weeds with herbicides or flaming does not disturb the soil, and no new weed seeds will be brought close to the soil surface. After using the stale seedbed technique, care should be taken not to disturb the soil any more than is absolutely necessary during the seeding or transplanting process to minimize the amount of weed seeds that are brought up to the surface to germinate. Preemergence herbicides can also be used after to increase the efficacy of stale seedbeds. Any cultivation performed after should be kept extremely shallow (3/4" to 1" maximum) so as not to reposition any additional weed seeds.
On sandy, loamy or high organic matter soils, the soil should not crust and modern seeders should still work satisfactorily. On heavy clay soils, crusting could make this technique unusable.
Stale Seedbed Steps:
- Prepare the soil as if you are about to seed or transplant. If a soil-incorporated herbicide is used, it must be applied and incorporated at this time. The soil should have good moisture (irrigate with 1/4" of water if necessary).
- Wait as long as possible to allow weeds to germinate and emerge. Allow weed seedlings to grow to the third leaf stage, or at least to the first true leaf.
- If you're using transplants: flame the soil or make an application of Gramoxone, Scythe, Aim or Roundup (if registered for the crop) to the soil surface before transplanting. Transplant the crop (without dragging any additional soil off the bed) and then apply any preemergence herbicide, which you would normally use, to the soil surface.
- If the crop will be seeded: Gramoxone, Scythe, Aim or Roundup (if registered for the crop) or flaming may be applied just before or just after seeding (see the label). After seeding, apply any preemergence herbicide which you would normally use to the soil surface. CAUTION: If the crop has already been seeded, be careful that the flaming process does not injure the crop seed or the emerging crop seedling.
Check the current herbicide label and recommendations by crop to determine if Gramoxone, Scythe, Aim or Roundup is registered for use in that crop. Gramoxone, Scythe, Aim and flaming will have minimal long-term effect on established perennial weeds. For cucumbers, melons, squash, pumpkin, peppers and eggplant, Roundup must be applied at least three days prior to seeding or transplanting.
In cases where Roundup is registered, it can also be used for control of perennial weeds, such as quackgrass and dock, prior to soil preparation. After application, delay tillage for three to five days. There is no residual weed control. See the label for directions.