Pigweed and Reducing Seedbanks

This video features Robert C. Scott, Professor and Extension Weed Scientist at Lonoke Extension and Applied Research Center, and was produced by Ross Macartney, videographer with the University of Arkansas Division of Agriculture--Extension. To contact him with questions regarding this or other podcast you may contact him at rmacartney@uaex.edu or visit their website at www.uaex.edu




Amaranthus palmeri (also
referred to as Palmer amaranth or
Palmer pigweed) is considered the
most troublesome weed in Arkansas
crop production. The rapid growth,
aggressive competition, extremely
prolific seed production and germina­
tion throughout the season make
Palmer amaranth a multimillion
dollar pest each year in our state.
Glyphosate­tolerant crops, espe­
cially cotton and soybean, have been
readily adopted by farmers. Currently,
greater than 98% of these crops
planted in Arkansas are glyphosate­
tolerant. Adoption of glyphosate­
tolerant crops has allowed farmers to
increase conservation tillage programs
and farm a larger number of acres
with less equipment and labor. In
Arkansas, the number of farms with
greater than 2,000 acres has
increased by 30% since the adoption of
glyphosate­tolerant crops.
Most of the common agricultural
practices in use today are built around
the use of Roundup Ready®.

Glyphosate has also been the most
effective means of controlling Palmer
amaranth in cotton. For this reason,
there is great concern over the devel­
opment of glyphosate­resistant Palmer
amaranth. Pigweeds that cannot be
controlled with glyphosate add
tremendous cost and cause major
shifts in our agricultural production
practices. This threat has resulted in
an intense interest in developing
plans for the prevention and manage­
ment of Palmer amaranth in cotton
and soybean.

A Palmer amaranth population
found in Mississippi County during
the 2005 growing season was the first
confirmed case of glyphosate­resistant
pigweed in Arkansas. Since that time,
the resistant biotypes have infested
all cropping counties in eastern and
central Arkansas.

Field and greenhouse experiments
have identified Palmer amaranth
biotypes that demonstrate varying
levels of resistance. Biotype 1 is
considered to have a lower level of
resistance, and when treated with
field doses of glyphosate shows
varying levels of symptoms such as
chlorosis, necrosis and stunting.
The apical bud is often destroyed,
but regrowth occurs from lower
auxiliary buds.

Category:

Education

Tags:

• university
• arkansas
• division
• agriculture
• cooperative
• extension
• Amaranthus
• palmeri
• Liberty
• Link
• soybeans
• aggressive
• pigweed
• species
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