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

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BROCCOLI AND EDAMAME RESPONSES TO VINEGAR APPLICATION FOR WEED
MANAGEMENT. C.B. Coffman, J. Radhakrishnan, and J.R. Teasdale, USDA-ARS,
Beltsville, MD.
ABSTRACT
Cole crops and brassicas are commonly grown by small conventional and organic
farmers in the U. S. Broccoli (Brassica oleracea L. var. italica) is popular at farmers'
markets and subscribers to CSAs, thus it is an important source of farm income. In the
mid-Atlantic region, broccoli is usually grown as a spring or fall crop, and weeds are
usually abundant and competitive unless successful management systems have been
utilized. Edamame (Glycine max L.) is a summer field crop often grown using organic
methods for weed management. Vinegar application has been investigated as a method
for weed management in edamame for several years on an organic farm in Buckeystown,
MD. Fall broccoli response to vinegar applications was investigated at the Beltsville
Agricultural research Center in 2006. The objective of this project was to evaluate crop
responses to basal applications of 20% acetic acid vinegar for within-row weed control.
Edamame (var. 'Mooncake’) was sown on 27 May 2006 at a rate of 170,000 seeds/A in
36-inch rows. Experimental plots consisted of three 20-foot rows with the center row
being the treated portion of the plot. Treatments were (1) vinegar applications to withinrow
weeds at the base of the crop plants, (2) unweeded control, and (3) hand-weeded
control. Treatments were replicated 4 times and were randomly placed throughout the
field. Vinegar applications were made on 31 July 2006 using a hand sprayer. Vinegar
was applied to weeds to achieve complete coverage until runoff. Crop plants were 21-31
inches high when treatments were applied. Weeds between rows were controlled by
cultivation. Weeds in the hand-weeded control were removed two times during the
growing season. Treatments were visually rated and harvested 25 September 2006.
There were no significant differences in visual ratings among treatments. Total biomass
and grain yields will be determined. Broccoli (var. ‘Packman’) transplants were placed 18
inches apart in 5-foot rows in a clean, cultivated field on 8 August 2006. Experimental
plots consisted of three 20-foot rows with the center row being the treated portion of the
plot. Treatments were the same as those in the edamame investigation. Treatments
were replicated 4 times and randomly arranged in the field. Vinegar applications were
made on 31 August 2006 to the basal portion of the crop plants. Broccoli plants treated
with vinegar showed diminished leaf turgor compared to the non-vinegar treated plants
within 30 min of application. Weeds between rows were removed via cultivation. Visual
rating and crop harvest occurred on 3 October 2006. Heads were cut to a length of 7
inches and fresh weights recorded. Plants treated with vinegar did not differ in size from
plants in the controls, although the lower leaves were chlorotic. Broccoli head counts
were 8% higher than the unweeded controls and equivalent to the hand weeded
treatment. However, total head weights and mean individual head weights were 25 and
30% lower for the vinegar treatments than for the hand weeded and unweeded controls,
respectively.
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