Table 6.  Preplant or preemergence herbicides for weed control in no-tillage soybean in a birdsfoot trefoil and/or crownvetch cover crop.

Blue line See specific product label to determine correct rate for the soil type and weed species found in individual fields.

GENERAL INFORMATION:

Blue line Weeds and unsuppressed cover crops are a chief cause of low soybean yields.
Blue line Many perennial weed problems can be controlled with Roundup or Touchdown before tillage or planting of soybeans. Glyphosate rates should not exceed 0.5 lb/A pre or post to the soybeans to avoid excessive crownvetch suppression. Because of the reduced rate and suggested early treatment, a residual herbicide treatment will always be needed for both no-till and min-till soybeans. Pursuit is one of the better herbicides for dandelion suppression but almost any other residual herbicide could be used for annual weed control.
Blue line Glyphosate or sulfosate will not suppress birdsfoot trefoil enough.
Blue line Post emergence glyphosate is safe only on Roundup Ready soybeans.
Blue line Preplant tillage will suppress both crownvetch and birdsfoot trefoil but also greatly thin the stand.
Blue line Maintaining a cover crop is almost impossible in drilled soybeans because of excessive competion from the beans.
Herbicide No. Product/A lb ai/A Remarks Weeds Controlled
No-Till -- To suppress the cover crop, apply treatment 21 when dandelion are in full bloom or at least a week before the soybeans are planted. Roundup or Touchdown can be tank mixed with treatment 22 and applied preplant or preemergence.
Min-Till -- Use treatment 21 for control of perennial weeds not controlled by tillage. Apply 5 days before planting to allow time for translocation to weed roots and rhizomes. Follow with treatment 22.
Roundup 4S
(glyphosate) plus		 21 1 pt
or		 0.5
or		 Read the label. Best when applied when dandelion are in full bloom. Use flat-fan nozzle. Annual weeds may be any size. Established weeds should have 6 to 8 inches of leafy growth. Apply at least five days before tillage or planting in 5 to 10 gal water. Birdsfoot trefoil and crownvetch must be well established. Top and root kill of most established biennial and perennial weeds; provides good suppression of crownvetch but poor suppression of birdsfoot trefoil. Weak on dandelion.
Sencor 75DF
(metribuzin)
plus		 2.1-4.2 oz
plus		 0.1-0.2 lb
plus
nonionic surfactant
if needed.
Can be Tank mixed with treatment 22 and applied before planting or emergence of soybeans.		 2 qt/100 gal label rate
Pursuit ECO-PAK
plus		 22   1.44 oz
plus		 0.063 lb
plus		 Read the label. May be used on regular or Roundup Ready soybeans. Apply preemergence in min-till. Tank-mix with treatment 21 and apply preplant or preemergence in no-till.   Annual grasses and broadleaves, TR pigweed and lambsquarters; suppression of dandelion.  
Prowl 3.3E1 for dandelion suppression and residual annual weed control. 1.8 - 2.4 pt 0.75 - 1.0
Postemergence Roundup -- Can be used for cleanup of any weeds missed by tillage and/or the preplant or preemergence treatment and for further suppression of the cover crop on Roundup Ready beans only.
1 Pursuit Plus is a prepackage mix of Pursuit and Prowl (0.2 + 2.7#ai/gal -- enough for 3.2 acres.

This page was last modified on 2/20/2004