For maximum control of bindweed in summer fallow we recommend the use of a tank mix of eight ounces Picloram (Tordon 22k or Outpost 22K) with 32 ounces of 4Number 2,4-D Amine per acre. This herbicide combination must be applied at least 60 days before planting or wheat stunting may result.
We recommend that the Tordon / 2,4-D tank mix be applied to the bindweed in the summer fallow in late May or June when the first flower buds begin to appear on the bindweed. Best results seem to be achieved by tilling the summer fallow first in the early spring and spraying the bindweed after the re-growth of at least 12-inch runners to make sure that all of the bindweed plant is being treated.
Bindweed should be sprayed by ground application equipment with 20 gallons of water per acre or maximum amounts of surfactants when less than 20 gallons is used.
Persistence over the course of many years is the only thing that can kill an established bindweed plant.
When to Treat
The later in the summer you treat bindweed with Picloram, the more likely you will have wheat stunting. Bindweed is best treated in the spring or fall when bindweed is growing actively and weather conditions are not hot and dry. Bindweed treatments in July and August do not work as well as treatments done earlier in the summer and are more likely to result in damage to wheat.
Picloram may be applied tank-mixed with Landmaster instead of 2,4-D to control other broadleaf weeds and grasses in the stubble. Landmaster is not available for cost share through the County.