Upload
plantscienceconsulting
View
11
Download
0
Tags:
Embed Size (px)
Citation preview
Optimising the impact of glyphosate
- Glyphosate resistance- Factors affecting glyphosate performance- Improving glyphosate performance
Plant ScienceConsulting
Glyphosate resistance
Winter weeds
Year
Nu
mb
er o
f p
op
ula
tio
ns
1996 2000 2004 2008 20120
100
200
300
400
500
600
Annual ryegrass
Wild radish
Red brome
Great brome
Summer weeds
Year
Nu
mb
er o
f p
op
ula
tio
ns
2006 2008 2010 2012 20140
20
40
60
80
100 Barnyard grass
Liverseed grass
Fleabane
Windmill grass
Sowthistle
1996-2014 2007-2014
Confirmed cases in Australia
Where & why has glyphosate resistant ryegrass evolved?
Intensive use of glyphosate >15yr with little alternative weed control practices
Uni of Adelaide random weed surveys between 2004-2014(Glyphosate resistance)
16%(2012)
1%(2013)
Facts about glyphosate resistant weeds
• All growth stages are resistant- seedlings, pollen etc.
• Younger growth stages can be more sensitive.• Resistance transferred by pollen & seed• Progeny from survivors can be more resistant
(accumulation of mechanisms)
Increasing the level of glyphosate resistance: mechanisms are additive
Surv
ival
(%)
TS
S
Translocation
Cross: Translocation + TS
Reduced glyphosate efficacy
– Herbicide resistance (weak or strong)– Depends on type of resistance mechanism
• Target-site resistance: weak to strong (not common)• Increased expression of EPSP (brome)• Uptake and translocation/ sequestration (common)
– Depends on the nr of resistance mechanisms present in individuals
Percent survival (%) of a selection of grower resistance tests from 2013 and 2014 treated with Glyphosate (540g ai/L). Data ranked according to percent survival at 1000ml/ha.
Different resistance profiles! Data courtesy of P. Boutsalis, Plant Science Consulting
Reduced glyphosate efficacy
• The below factors are not independent of each other:– Treating older/ larger plants– Poor coverage sub-lethal rate
• Nozzles, water rates, calibration
– Stressed plants • temperature extremes, moisture, nutrition, pest damage
etc. affect translocation etc.• Reduced efficacy at high temperatures (better effect
spraying high 20oC’s than 30oC’s)
– Dust covering leaves sub-lethal effect
Improving glyphosate efficacy
– Increased glyphosate rates can aid in buffering the effect of:• Treating older plants
• stressed plants
• high temperatures
• Poor coverage
• Dust covering leaves
– Increased glyphosate rates can improve control of HR individuals.
– Avoid using higher rates unless a resistance test confirms effective.
– Do not let glyphosate resistant individuals set seed to avoid
accumulation of resistance mechanisms.
– Rotate from glyphosate even if no resistance (paraquat products/
residuals eg. bromacil along fencelines/ non-cropped areas).
– Test for glyphosate resistance (several rates) important.
Quick-Test: Survivors resistant ??
Glyphosate resistance testing
• Seed Testing from 2014:– 275 ryegrass samples & 251 Glyphosate testing
requests (91%)– Data not available on % resistant samples
• Seed Testing from 2013:– 305 ryegrass samples & 232 Glyphosate testing
requests (76%)– 71% exhibited glyphosate resistance
Plant ScienceConsulting
1000ml/ha 1500ml/ha
Glyphosate 540g ai/L
1000ml/ha 1500ml/ha
Survivors to 1000ml/ha indicates low-level glyphosate resistance
which is becoming common
Are survivors always Glyphosate resistant?
Paraquat mixtures, bromacil
2L/ha Glyphosate
Control of Glyphosate -R ryegrass on a fence line in Kapunda SA with herbicide mixtures-
2013Fenceline was sprayed in late winter, 2013
Kapunda SA, 2013
At sprayingUntreated
Uragan 3kg/ha + Basta 5 L/haUragan 3kg/ha + Paraquat 2 L/ha
Life Impact The University of Adelaide
Life Impact The University of Adelaide
Life Impact The University of Adelaide
Life Impact The University of Adelaide
Life Impact The University of Adelaide
Life Impact The University of Adelaide
The End
Plant ScienceConsulting