Sunflower and Rotational Crop (Corn) Response to DPX-R6447 and Sulfentrazone
P. Hendrickson  

The study was conducted on a Heimdal silt loam soil with a 6.7 pH and 2.9% organic matter.  Sunflower (SF290 NL) was seeded on June 11, 1999, into 30-inch rows at 20,000 seeds/A.  DPX-R6447 and sulfentrazone were applied preemergence (PRE) on June 15, 1999 to 20 by 50 ft plots at 1.07, 2.14, and 4.29 oz ai/A and 3, 4.29, and 6 oz ai/A; respectively.  Ethalfluralin applied PRE at 18 oz/A was included as a treated check.   The trial area was reseeded to corn May 29, 2000, into 30-inch rows at 30,600 seeds/A.  Weeds were controlled with post-emergence herbicides and cultivation to reduce the effect of weed interference on corn yield.

Sunflower injury was rated less than 10% in all plots and did not differ significantly from the untreated check (Table).  Sulfentrazone reduced common lambsquarters densities from 73 to fewer than two plants per three ft2, and redroot pigweed from 41 to fewer than 10 plants per three ft2.  No differences in common purslane and yellow foxtail densities were detected.  Corn injury was rated less than 10% in all plots and did not differ significantly from the untreated check.  Corn yield was not affected by DPX-R6447, sulfentrazone or ethalfluralin carryover.

Table.                      
Sunflower Weed density Corn
6/29/99 CHEAL1 AMARE2 POROL3 SETLU4 Injury Yield
Treatment Rate Injury 6/14/00   6/12/00 7/6/00 7/20/00 11/3/00
oz ai/A %

---------  # of plants / 3 ft2  ----------

---------  %  --------

bu/A
DPX-R6447 1.07 3 50 23 4 2 0 0 0 130
DPX-R6447 2.14 7 35 31 10 4 0 0 0 124
DPX-R6447 4.29 3 33 27 5 3 7 3 0 130
Sulfentrazone 3 2 1 8 5 1 3 3 0 119
Sulfentrazone 4.29 7 0 5 3 1 0 0 0 115
Sulfentrazone 6 7 0 1 3 2 0 0 0 115
Ethalfluralin 18 4 18 10 6 1 0 0 0 114
Untreated check 0 0 73 41 8 9 0 0 0 122
LSD 0.05   N.S. 32 23 N.S. N.S.   N.S. N.S. N.S. N.S.
1CHEAL = common lambsquarters Chenopodium album)
2AMARE = redroot pigweed (Amaranthus retroflexus)
3POROL = common purslane (Portula oleracea)
4SETLU = yellow foxtail (Setaria glauca)
 
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