Transcript Aminopyralid Injury to Potatoes

Kevin B. Kelley and Lloyd C. Haderlie
AgraServ, Inc., American Falls, ID
Aminopyralid
 Auxinic herbicide labeled for use on rangeland,
permanent grass pastures, CRP land, non-cropland
areas, and natural areas.
 Very active on several annual and perennial broadleaf
weeds, including Canada thistle.
 Known to pass through animals that consume treated
forage and be present in manure and urine similar to
picloram.
 Shorter soil half-life than picloram.
Aminopyralid Injury to Potatoes
Research Prompted by Farmer Complaints
 Aerial applications of aminopyralid to range/pasture in
2008
 Potatoes bordering pasture in 2008 and 2009 showed
injury symptoms and yield loss
 Weeds sensitive to aminopyralid in potato fields didn’t
show injury
 Laboratory analysis of potato foliage and tubers
resulted in positive detection of aminopyralid
Aminopyralid Affect on Potatoes
Persistence in the soil?
Potato sensitivity?
 Growth stage differences?
 Daughter tuber response?
Methods - Timing
 Fall Soil Carryover
 Applied Nov. 7, 2009
 Spring Preplant
 Applied May 18, 2010 – One day before planting
 In Season
 Early – Applied 2 weeks after emergence
 Mid-Season – Applied late July near row closure
 Daughter Tuber Plant Response
 Applied Aug. 31, 2009
 Treated tubers planted May 2010
 Known to be a very sensitive assay for picloram
Methods - Rates
 Aminopyralid – Use rate range - 53 to 123 g ai/ha
 applied from 44 g ai/ha (~50%) down to 0.044 g ai/ha
(0.05%)
 Picloram – Average use rate - 280 g ai/ha
 applied at 4.4 and 44 g ai/ha
 Clopyralid – Max use rate of 280 g ai/ha
 applied at 26 or 280 g ai/ha
 Dicamba – Average use rate of 560 g ai/ha
 applied at 56 or 560 g ai/ha
Fall Soil Carryover
Percent Injury
Potato Injury July 16th
c
bc
b
b
Aminopyralid – g ai/ha
LSD – 4 (P=0.1)
Fall Soil Carryover
Total Potato Yield
a
a
a
a
CWT per Acre
a
Aminopyralid – g ai/ha
LSD – 41 (P=0.1)
Fall Soil Carryover
US #1 Potato Yield
a
a
a
CWT per Acre
a
b
Aminopyralid – g ai/ha
LSD – 37 (P=0.1)
Spring Preplant Applied
Potato Injury Aug 10th
Percent Injury
a
b
c
cd
a
b
b
cd
d
Aminopyralid
Rates in g ai/ha
LSD – 17 (P=0.1)
Spring Preplant Applied
Total Potato Yield
ab
bc
abc
CWT per Acre
a
Aminopyralid
Rates in g ai/ha
LSD – 78 (P=0.1)
In-Season Applied
Potato Injury Aug 10th (6 or 2 WAA)
Percent Injury
a
c
b
c
de d
g g
f
de
g fg
Aminopyralid
e
fg g g
Aminopyralid
Two Weeks After Emergence
Near Row Closure
Rates in g ai/ha
LSD – 6 (P=0.1)
In-Season Applied
US #1 Potato Yield
CWT per Acre
ab
a-e
b-e
abcabc
a-d
ef
a
a-d
a-e
cde
def
ef
fg
h
gh
Aminopyralid
Aminopyralid
Two Weeks After Emergence
Near Row Closure
Rates in g ai/ha
LSD – 71 (P=0.1)
Daughter Tuber Plant Response Potato Injury Aug 10, 2010 (Sprayed 2009)
Percent Injury
a
b
c
c
c
Aminopyralid – g ai/ha
LSD – 9 (P=0.1)
Daughter Tuber Plant Response –
Total Potato Yield (Sprayed 2009)
a
CWT per Acre
a
a
b
c
Aminopyralid – g ai/ha
LSD – 67 (P=0.1)
Summary
 Aminopyralid injured potatoes and reduced yield and
quality following all scenarios tested including fall
applied to soil.
 Injury levels were similar to or exceeded that caused by
picloram
 Greater rates of dicamba or clopyralid were required to
cause potato injury.
 Potatoes appear to be especially sensitive to
aminopyralid.
 All potatoes were saved for seed grow out in 2011.
Questions?