Proceedings of the Sixty-first Annual Meeting of the Northeastern ...

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THE RESPONSE OF FIELD AND CONTAINER GROWN ORNAMENTALS TO
SULFENTRAZONE AND FLUMIOXAZIN. M.W. Marshall and B.H. Zandstra, Michigan
State University, East Lansing.
ABSTRACT
Field studies were conducted in 2006 to evaluate tolerance of container and field
grown ornamentals to various rates of sulfentrazone and flumioxazin. Treatments
included sulfentrazone at 0.14, 0.28, and 0.56 kg/ha and flumioxazin at 0.28, 0.56, and
1.02 kg/ha. An untreated control was included for comparison. Container grown
ornamental species included periwinkle (Vinca minor L.), butterfly bush (Buddleia davidii
'Adonis Blue'), inkberry holly (Ilex glabra ‘Ivory Queen’), orange coneflower (Rudbeckia
fulgida var. fulgida ‘Meadowbrite’), and boxwood (Buxus microphylla ‘Green Mountain’).
Field grown ornamental species included burning bush (Euonymus alatus compactus),
azalea (Azalea ‘Cannon’s Double’), boxwood, daylily (Hemerocallis ‘Evelyn Claar’),
coral bells (Heuchera micrantha ‘Palace Purple’), hosta (Hosta fortunei 'Gold Standard'),
and shasta daisy (Leucanthemum x superbum 'Snowcap'). In the container study,
sulfentrazone was applied on July 15, 2006 and August 22, 2006. In the field study,
sulfentrazone was applied on June 22, 2006 and July 24, 2006 and flumioxazin was
applied on June 22, 2006. Experimental design was a randomized complete block
design with 3 replications. Individual plot sizes were 0.6 by 0.9 m and 5.4 by 10.6 m in
the container study and field study, respectively. Plant injury ratings were evaluated 7,
14, and 28 days after treatment (DAT) on a 0 to 9 scale with 0 indicating no injury and 9
equal to crop death. Herbicides were applied in water over-the-top of newly transplanted
ornamentals at a carrier volume of 187 L/ha with a pressure of 207 KPa. Boxwood
grown in container and the field showed very little injury to sulfentrazone and
flumioxazin, regardless of the rate. Plants most sensitive to sulfentrazone included
butterfly bush, orange coneflower, coral bell and daylily. In addition, daylily, Hosta, and
Shasta daisy were sensitive to over-the-top applications of flumioxazin, especially at
1.02 kg/ha. Sulfentrazone injury, regardless of species, included browning of the leaves
where the spray intercepted the leaf. New growth at the base of the plant did not exhibit
these symptoms. Butterfly bush showed moderate injury at the 0.28 and 0.56 kg/ha
sulfentrazone rate 7 DAT. By 28 DAT, injury was only apparent at the 0.56 kg/ha rate.
In the field study, boxwood, Azalea, and burning bush exhibited very little response to
flumioxazin and sulfentrazone, regardless of rate. At 14 and 28 DAT, daylily, Hosta,
and Shasta daisy injury at 0.56 kg/ha ranged from 5.7 to 8.7, with the Hosta being the
most sensitive. By the end of the trial; however, these plants had regrown and
recovered to sizes not significantly different from the untreated control. In general,
sulfentrazone and flumioxazin were generally safe on the container and field grown
woody ornamental plants. Sulfentrazone at 0.28 and 0.56 kg/ha should be used with
caution on container and field grown orange coneflower, butterfly bush, Hosta, and
daylily. Since both formulations were liquids, a granular formulation maybe safer on
these sensitive species.
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