aminopyralid and clopyralid residues in unexpected … · • aminopyralid and clopyralid – both...
TRANSCRIPT
Aminopyralid and Clopyralid Residues in Unexpected
Places
Steven Seefeldt
Background
• Aminopyralid and Clopyralid – Both are synthetic auxins
• Auxin is a plant hormone – Involved in cell division – Involved in cell growth
• Auxins move in the phloem to the growing points
Background
• Aminopyralid and Clopyralid – Both are synthetic auxins
• Auxin is a plant hormone – Involved in cell division – Involved in cell growth
• Auxins move in the phloem to the growing points
– Both originally discovered by someone at Dow AgroSciences
– Both control a variety of broadleaf plants
Background Clopyralid
• Discovered 1961 • Sold in 1978 in Europe • Sold in 1987 in US • Curtail, Stinger, Confront
Background Clopyralid
• Discovered 1961 • Sold in 1978 in Europe • Sold in 1987 in US • Curtail, Stinger, Confront • Now off patent • Post emergence in pasture, rangeland,
and CRP • Half life 12-70 days – microbial
Background Aminopyralid
• Sold as Milestone • Still on patent • Expensive • Sold about 2005
Background Aminopyralid
• Sold as Milestone • Still on patent • Expensive • Sold about 2005 • Used in rice, pastures rangeland, ROW,
wheat, oil palm, and rubber plantations • Half life 25 to 35 days (averages) • Photodegradation then microbial
Some Label Restrictions
Use in Alaska
• Control of invasive weeds • Spot spraying for perennial sowthistle • Control of orange hawkweed in pastures and
hay fields
Examples of Injury, potatoes
Examples of Injury, raised beds
Marigolds Potatoes Tomatoes
Carry over research design
H1 H2
H3 H4
H5 H6
• Six treatments – Control – Glean 75DF (0.33 oz/A) – Ally 60DF (0.1 oz/A) – Banvel (3 fl oz/A) – Stinger (0.33 pt/A) – Milestone (7 fl oz/A)
• Applied the summer of 2011
Carry-over weed injury – Palmer
Weed Control Aminopyralid Clopyralid Plants per meter square
Chickweed 48 2 74 Corn Spurry 89 3 166 NL Hawksbeard 668 0 11 Dragonhead 24 0 1 Lambsquarters 54 1 27 Pineapple Weed 8 0 0 Shepherd’s Purse 504 0 11 Total 1,395 6 290
Dose-response research design 1X glean
0.5X glean 0.25X glean
0.125X glean 0.062x glean No herbicide
Barley Canola Potato Lettuce Carrot Kale Nocrop
Visual injury – Dose response
Aminopyralid Clopyralid
Potato response above ground
0
20
40
60
80
100
0 0.06 0.125 0.25 0.5 1
% o
f con
trol
Aminopyralid dose (1 = 7 fl oz/A)
Delta
Fairbanks
Palmer
0
20
40
60
80
100
0 0.06 0.125 0.25 0.5 1
% o
f con
trol
Clopyralid dose (1 = 0.33 pt/A)
Visual injury – Crop + Weed
Aminopyralid Clopyralid
The weed as a bio-assay
• Can we use weeds to estimated herbicide residuals?
• What are potential problems?
0 10 20 30 40 50 60 70 80 90
100
0 0.06 0.125 0.25 0.5 1
% o
f con
trol
Aminopyralid rate (1 = 7 fl oz/A)
Delta
Palmer
Milestone D
Milestone P
Potato
Crepis
Potato response below ground
0
5
10
15
20
0 0.06 0.125 0.25 0.5 1
Pota
to h
arve
st (l
b)
Aminopyralid dose (1 = 7 fl oz/A)
Delta Palmer
0
5
10
15
20
0 0.06 0.125 0.25 0.5 1 Po
tato
har
vest
(lb)
Clopyralid dose (1 = 0.33 pt/A)
Is there herbicide in the tuber?
Is there herbicide in the tuber?
• Tubers were sent to the Montana Department of Agriculture Laboratory at Montana State University to extract the herbicide
• Dr. Rick Boydston with ARS in Prosser, WA funded the work ($150/sample)
Extraction Results
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0 0.06 0.125 0.25 0.5 1
Am
ount
ext
ract
ed (p
pm)
Aminopyralid rate (1 = 7 fl oz/A)
Delta
Palmer
Is that herbicide herbicidal?
Is that herbicide herbicidal?
Aminopyralid
Is that herbicide herbicidal?
clopyralid
Conclusion
• Aminopyralid and clopyralid management – Their residues are in the plant and soil – They pass through ruminants unchanged – They will accumulate in potato tubers – Some plants are more sensitive than others – There are potential bioassays – Half lives are currently unknown
Acknowledgements
• Erin Carr, Jennifer Kapla, Dr. Rick Boydston, Dr. David Barnes, Mingchu Zhang, Bob Van Veldhuizen, and the staff at the Palmer, Fairbanks, and Delta Junction Agriculture Experiment Stations.