TY - JOUR
T1 - Resistance to glyphosate in Lolium rigidum. I. Bioevaluation
AU - Pratley, James
AU - Urwin, Nigel
AU - Stanton, Rex
AU - Baines, Peter
AU - Broster, John
AU - Cullis, Kerrie
AU - Schafer, David
AU - Bohn, Joseph
AU - Krueger, Roger
PY - 1999/7/1
Y1 - 1999/7/1
N2 - Glyphosate is the world's most widely used herbicide. It is nonselective and has been used to control a broad range of weed species for the past 20 yr, without the appearance of resistant weed biotypes. However, a biotype of Lolium rigidum from a field in Northern Victoria, Australia, in which glyphosate had been used for the past 15 yr, failed to be controlled by label recommended rates. Based on LD50 values from pot dose-response experiments, this biotype exhibited resistance to glyphosate and was nearly 10-fold more resistant compared to the susceptible biotypes tested. The biotype was resistant to three different salts of glyphosate. The biotype was also nearly threefold more resistant to diclofop-methyl but was susceptible to other commonly used selective and broad-spectrum herbicides. Between the two-leaf and tillering stages of development, a susceptible biotype exhibited a small but significant decrease in tolerance to glyphosate, whereas tolerance of the resistant biotype remained unchanged with age. The resistant phenotype was verified in experiments in which seed was germinated in the presence of glyphosate. Observations on shoot and root growth of seedlings in these experiments suggested that the resistance mechanism might be associated more with the shoot than with the root.
AB - Glyphosate is the world's most widely used herbicide. It is nonselective and has been used to control a broad range of weed species for the past 20 yr, without the appearance of resistant weed biotypes. However, a biotype of Lolium rigidum from a field in Northern Victoria, Australia, in which glyphosate had been used for the past 15 yr, failed to be controlled by label recommended rates. Based on LD50 values from pot dose-response experiments, this biotype exhibited resistance to glyphosate and was nearly 10-fold more resistant compared to the susceptible biotypes tested. The biotype was resistant to three different salts of glyphosate. The biotype was also nearly threefold more resistant to diclofop-methyl but was susceptible to other commonly used selective and broad-spectrum herbicides. Between the two-leaf and tillering stages of development, a susceptible biotype exhibited a small but significant decrease in tolerance to glyphosate, whereas tolerance of the resistant biotype remained unchanged with age. The resistant phenotype was verified in experiments in which seed was germinated in the presence of glyphosate. Observations on shoot and root growth of seedlings in these experiments suggested that the resistance mechanism might be associated more with the shoot than with the root.
KW - Biotype
KW - Germination inhibition
KW - Glyphosate ammonium
KW - Glyphosate isopropylamine
KW - Glyphosate trimesium
KW - Herbicide tolerance
KW - LOLRI
KW - Multiple resistance
KW - Resistance phenotype
KW - Visual injury rating
UR - http://www.scopus.com/inward/record.url?scp=0032725930&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032725930&partnerID=8YFLogxK
U2 - 10.1017/s0043174500091992
DO - 10.1017/s0043174500091992
M3 - Article
AN - SCOPUS:0032725930
SN - 0043-1745
VL - 47
SP - 405
EP - 411
JO - Weed Science
JF - Weed Science
IS - 4
ER -