Cereals 2024 Weed Control Part 2 Herbicide Use and Pesticide Resistance Flashcards
What are key active ingredients in widely used herbicides?
- Mesosulfon-methyl (Alister / Pacifica)
- Diflufenican (DFF / Alister / Firebird )
- Iodosulfuron-methyl (Hussar/Alister / Pacifica)
- Pedimethalin (PDM / Flight (Crystal )
- Sulphonyl-Urea’s (SU) many of
- Hormonal (CMPP / MCPA)
- Fluroxypyr (Starane / Hurler / Reaper,
- Ioxynil, bromoxynil (HBN’s)
- Isoproturon (IPU)
Isoproturon (IPU) use in winter cereal crops
1- What is it and whats it used on?
2- Whats grass weed control based on?
3- Whats it available under, what names?
4- What country have big problems with IPU’s?
5- What was it banned in Ireland ad EU?
1- a residual soil-acting herbicide with activity on grass weeds and broad-
leaved weeds
2- Grass weed control was based on the use of IPU before tillering of
the grass / some b/l weeds, historically was useful for wild oats control
3- availiable under a range of brandnames - Arelon, Fieldguard,
Tolkan, but mostly used in a product which is a formulation
with other a.i.’s
4- In UK IPU had big problems with leaching into waterways and
was banned 15 years ago
5- In Ireland and EU - banned from 2017 onwards
1- What is DFF?
2- What does Diflufenican go into?
3- When is pre and post emergence on winter wheat and barley?
4- What is resistant ?
5- What are the new, high activity products alternatives?
1- Is a residual soil-acting herbicide with
good activity on broad-leaved weeds and useful
grass weed activity
2- Diflufenican goes into tank mix combinations
3- end-Sept. to early-March
4- fumitory is resistant (also resistant to Ally)
5- new high activity products alternatives are
Firebird & Alister
What are the 2 current options for weed control in winter cereals?
Firebird
Alister
What is Firebird?
is a residual soil-acting herbicide with
activity on grass weeds and broad-leaved weeds
– DFF + flufenacet (400+200 g/l) with a recommended
rate of 0.3 l/ha
– Early post-emergence on winter wheat and barley
– Very good on annual meadowgrass (AMG)
– Weakness on cleavers, charlock
What is Alister?
is a post-emergence herbicide for GS 13 to 30
and is broadspectrum with strength on AMG
DFF + mesosulfuron + iodosulfuron with a rate of 0.75-
1.0 l/ha
Whats a good spraying technique for small grass weeds?
IMPT
Correct spraying technique is very important
- Boom height
What optimizes the performance of herbicides?
- Product choice / Formulation Important but …..
- Sprayer in good working order and properly calibrated
- Nozzle Choice
- Reducing water volumes can improve timing
- Boom Height 50cm above target for 110 fan nozzles
- Forward Speed determined by keeping boom level
One years weed is…
7 years seed
Sterile Brome Control Options:
1- Where is this a widespread problem?
2- What is the problem in achieving?
3- What is broadway star mix?
4- What does it work on ?
5- What is use ideal?
6- What other weeds does it have a good spectrum on?
7- What is sterile brome control options weak on?
1-In min-till system
2- Problems with achieving high level of control 99%
3- Broadway Star (pyroxsulam + florasulam) in a granule
formulation
4- Contact only action so only works on weeds present so
use medium to fine nozzles and an adjuvant
5- Early-autumn use is ideal but also in spring – up to GS
32 (less efficacy)
6- good spectrum on other weeds – wild oats, ryegrass
7- Weak on AMG (need pendimethalin mix)
1- What is a very important and big problem in cereal crops?
2- How fast can weeds multiply?
3- Is it a competitive weed?
4- Is it expensive to control with herbicides?
1- Wild oats are a very important
weed in cereal crops
2- Weed can multiply very fast x
100+ in two years
3- it is a very competitive weed
with the crop - reduces yield
and quality
4- expensive to control with
herbicides – Axial Pro at rates
from 0.6 – 0.85 l/ha
What is the target plus control for wild oats?
99%
Common weeds in Winter crops: (7)
- chickweed
- speedwell
- mayweed
- cleavers
- red deadnettle
- fumitory
- field pansy
Common weeds in Spring Cereals (6)
- chickweed
- speedwell
- fat hen
- red shank
- knotgrass
- corn marigold
1- Spring weed control in cereal crops:
Soft weeds?
2- Key “different” weeds are ?
– ‘soft’ weeds in good growing conditions with wider
‘window of opportunity’ to spray in suitable
weather conditions
– opportunities to reduce herbicide rates alone and in
mixture : typical cost is Euro 15-30/ha
2- key ‘different’ weeds are the polygonum weeds
If you get a question on tillage practices half your anwser is on weed control
Reduced herbicide rates alone and in mixture costs how much for spring weeds?
typical cost is Euro 25-35/ha
What is herbicide use dominated by?
sulphonyl urea’s
Herbicides are typically applied when? in Spring cereal crops:
typically
applied before the end of
tillering (GS 30)
Using sulphonyl urea herbicides in practice :
Ally / Cameo / Harmony / Calibre
Advantages: (5)
- excellent spectrum
- good performance where rates are reduced to 50- 75% of R.Rate
- excellent activity on previously difficult annual and perennial B/L weeds
- low dose rates 15-30 g/ha
- granule and tablet
formulations - wide window of appl. up to
flag leaf on all cereals - very compatible with other
crop protection products - low mammalian toxicity
What are disadvantages in using sulphonyl urea herbicides in practice :
Ally / Cameo / Harmony / Calibre
- sprayer contamination
- sensitivity of brassicae crops
to 1/70 of rate - recent emergence of resistant
weeds - chickweed, marigold
What are second generation SU herbicides?
Whats Issues with them?
What are key products?
More focussed spectrum targeting the control
of blackgrass, annual meadow grass, sterile
brome, cleavers etc
- Issues with resistance management strategies
- Key products
– Atlantis (UK) for blackgrass
– Alistar/Pacifica/Hussar for AMG / wild oats
– Pacifica and M for sterile brome control
– Eagle for cleavers control
What are 4 symptoms of herbicide resistance?
– Healthy plants beside dead plants of the same
species
– Poor control of one susceptible species when
other species are well-controlled
– Discrete weed patches
– Gradual decline in control over several years
Is herbicide resistance inherited?
Herbicide resistance is an inherited trait and
with repeated selection resistant plants
survive, multiply and dominate the weed
population
