Growing strawberries as an annual crop on black plastic requires a different weed management strategy than the perennial matted row strawberries. Weeds that have hard seed coats, such as vetch and clover, emerge for long periods of time and can establish in the row. They emerge in late fall or spring, grow under the plastic for a period of time, and emerge from any holes in the plastic.

With the loss of methyl bromide, alternative methods for weed control will be needed. Possible options include application of preemergence herbicides to the preformed bed before laying the plastic, postemergence herbicide(s) applied over the top of the strawberry crop, and hand removal.

When strawberries are planted year after year in the same field, an increase in weeds that are not controlled by the current weed management program should be expected. Rotation into different fields can prevent increases in persistent weeds. Avoid fields that have been previously treated with herbicides that have potential to persist and cause damage to strawberries. Information on crops that can be planted after herbicide use can be found on the herbicide label.

Three areas where weeds can easily establish in strawberries grown on plastic are as follows:

1. The middles between the rows have excellent fertility and moisture and, thus, can support weed growth easily. Once these weeds become established, they can easily shade strawberry plants growing in the row.
   The best practice is to apply a preemergence herbicide in the middles between the rows prior to weed emergence. Another option is to apply a postemergence herbicide to young, actively growing weeds. At this stage of weed growth, postemergence herbicide application is safest and most effective. NOTE: All herbicide applications between rows should be banded and not applied over the plastic. Herbicides can remain active on the plastic and crop injury can occur if herbicides are applied over the plastic. A third option for row middles is to seed ryegrass immediately after laying the plastic. In addition to weed suppression, ryegrass limits soil, wind and water erosion from the middles. Prior to strawberry harvest, the ryegrass can be suppressed then killed with sethoxydim (Poast). Growers sometimes apply wheat straw to middles. If straw is applied to the middles, use straw that contains no weed seeds.
2. Weeds often emerge from the hole around the strawberry plant. Weeds growing in this area compete with strawberries, often reducing growth, yield and quality. Additional stress can result in crop death. Thus, frequent scouting and hand removal are necessary to prevent this from happening. Small-seeded, broadleaf weeds can be more prevalent in the strawberry row. Alternative methods of control include applying a preemergence herbicide to the preformed bed prior to laying the plastic, applying a postemergence over-the-top herbicide, or hand weeding.
3. Weeds such as curly dock, vetch, horseweed, sow thistle and prickly lettuce often establish at the ends of fields. If these weeds are not controlled. they will produce seeds that are capable of moving into the production field. Thus, always scout non crop land such as the ends of fields, fence rows, and ditches, and implement cultural and/or chemical control measures when needed. Control weeds prior to flowering to prevent weed seed production.

The following herbicides are registered for use in strawberries.