Super weeds, causes, examples, herbicides, resistence, prevent super weeds.

1. SEMINAR
On
“ SUPER WEEDS ”
Presented by,
S. MANIBHARATHI
Reg. N0: 207010012
II M.Sc.,(Agri.) Agronomy
Department of Agronomy
Faculty of Agriculture
Annamalai University
(2020 - 2022 batch)

2. SUPER WEEDS

3. Outlines
Introduction
 Weeds
Herbicides
Herbicide Resistance
Types of Herbicide resistance
Super Weeds
Herbicide resistance weeds
Herbicide resistance management
How to prevent super weeds ?
Conclusion

4. INTRODUCTION :
Weeds
Herbicides
Herbicide resistance

5. WEEDS
 The term weed was coined by Jethro Tull .
 Weeds are unwanted and undesirable plants which
interfere with the utilization of land and water resources
and thus adversely affect human welfare. They can also be
referred as plant out of place.

6.  About 30,000 species of weeds have been listed in the
world, out of which nearly 18,000 species cause
serious damage in different ways resulting in
considerable losses to agricultural production.
 18 weeds identified as the most serious in the world.

7. YIELD LOSSES :
 Weeds compete with crop plants , largely for soil
moisture, nutrients and Sunlight.

8. Crop Yield loss % Crop Yield loss %
Wheat 10-60 Rice 10-100
Cotton 40-60 Sugarcane 25-50
Maize 30-40 Sorghum 45-69
Cumbu 16-65 Ragi 50
Horsegram 30 Jute 30-70
Niger 20-30 Soybean 10-100
Chickpea 10-50 Lentil 30-35
Greengram 10-45 Pigeonpea 20-30
Groundnut 30-80 Potato 20-30
Reduction of yield in major crops in India due to weed infestation
(Rao et al., 2014)

9. HERBICIDE
 Latin word = Herba (plant) + Caedre (to kill).
 Chemicals that kills or suppress the unwanted vegetations.
 In India 2,4-D First tested as herbicide in1946 and introduced at
commercially in field level in 1948.
 Maximum herbicides used are rice, wheat & plantation crops.

10. Herbicide Resistance :
 In India herbicide resistance was first reported in
wheat crop in Haryana.
 Where some biotype of Phalaris minor found
resistance to Isoproturon ( Malik and Singh, 1993) .
 Highest number of weeds found resistance against
atrazine herbicide (66 weed species) and maximum
number of weeds resistance has been reported in wheat
crop.
 Herbicide resistance is most serious problem of
present time.
 Currently there are 480 cases of herbicide resistance
in 252 plant species ( Sunil et al., 2020).

11. .
( Heap, 2021)

12. .
( Heap, 2021)

13. Major Types of Resistance :
.

14. OTHER TYPES OF RESISTANCE :
1.Simple resistance
2. Cross resistance
3. Multiple resistance
4. Reverse resistance
5. Creeping resistance
6. Phoenix resistance
7. Negative cross resistance
8. Co-resistance : (compound resistance)
Sunil et al.,2020

15. Factors affecting resistance development :
 Characteristics of weed
1. Initial frequency of resistant biotype
2. Annual growth habit
3. Selection procedure for evolution of resistant
population
 Characteristics of herbicides
 Cultural characteristics

16. RESISTANCE MECHANISM :
There are two following two mechanisms given by
Dekker & Duke (1995).
A). Exclusively resistance
a). Differential herbicide uptake
b). Differential translocation
c). Compartmentation (Sequestration)
d). Metabolic detoxification
B). Site of action of resistance
a). Target site alteration
b). Overproduction of site of action

17. Scenario of herbicide resistance in India :
 Herbicide resistance was originated over last 40 years.
 Discovery of atrazine resistance in Senecio vulgaris in 1968
(Ryan et al., 1970).
 Herbicide resistance has become major problem in 92 crops in 70
countries.
 Maximum resistance was found against traiazine group of
herbicides.
 In crops mainly in wheat, HR has developed in both grassy and
broad leaf weeds.
 Grassy weeds, P. minor & A. fatua resistance against
sulfosulfuron & clodinofop.
Senecio vulgaris

18. Cont..
 Repeated use of IPU over several years caused evolution of
resistance in P. minor in 1990s (Malik and singh,1993).
 Multiple resistance in P. minor has developed against
photosystem II inhibitors, ACCase inhibitors & ALS
inhibitors Heap (2016).
 P. minor resistant against Pinoxaden Kaur et al., (2015).
 Singh et al., (2016) HR in wild oat against application of
sulfosulfuron, clodinafop & fenoxaprop to population from
farmer’s field.
 Herbicide resistance in wild oat has been reported in 50
countries to >24 herbicides (Heap, 2016).
 Reports of herbicide resistance in P. minor in India are
Isoproturon,Sulfosulfuron,Clodinafop,Fenoxaprop,
Pinoxaden. (Bhullar et al., 2017)

19. What is super weeds ?
 “A weed which is extremely resistant to herbicides,
especially one created by the transfer of genes from
genetically modified crops into wild plants”.
 “Super weed” proposed by WSSA (Weed science society of
America) is “ Refers to a weed that has become resistant to
one or herbicide mechanisms of action due to their repeated
use, in the absence of more diverse control measures.

20. How are super weeds harmful ?
 They are highly toxic to broad leaf crops, including many of the
most common fruit and vegetable crops.
How do super weeds grow ?
Continual use of a single type of herbicide has led to weeds
developing resistance.

21. Occurrence procedure of herbicide resistant weed in
farm land :

22. S.NO SPECIES COMMON NAME
1 Lolium rigidum Rigid ryegrass
2 Avena fatua Wild oat
3 Amaranthus retroflexus Redroot pig weed
4 Chenopodium album Lamb’s quarters
5 Setaria viridis Green faxtail
6 Echinochloa crusgalli Barnyard grass
7 Eleusine indica Indian crowfoot grass
8 Kochia scoparia Mexican fireweed
9 Conyza canadensis Horse weed
10 Amaranthus hibridus Green pig weed
Heap (2006)

23. Eleusine indica
Echinochloa crusgalli
Chenopodium album
Avena fatua
Lolium rigidum

24. ..
( Heap, 2021)

25. Is super weeds will create a problem ?
As a result, super weeds can continue to infest
fields and siphon nutrients from valuable crops
planted there, leading farmers to use other costlier
and potentially harsher herbicides to control them.
What are examples of super weeds ?
Soybeans, cotton , alfalfa and sugar beets are
genetically engineered to be immune to the
company’s Roundup herbicide (Glyphosate).

26. .
( Heap, 2021)

27. .
( Heap, 2021)

28. .
( Heap, 2021)

29. How do super weeds affect the environment ?
 Already, a recent study found, 28 species
worldwide are resistant to 2,4-D and/or dicamba.

30. How do GMO cause super weeds ?
 These super weeds were spawned by overuse of
the chemicals on fields planted with herbicide
resistant crops, mostly GMO corn and soybeans
from Monsanto.

31. Are super weeds GMOs ?
 Super weeds are super only in their ability to resist
one or more specific herbicides.
Are super weeds real ?
Super weeds are all too real, and they have now
spread to over 60 million acres of our farmland,
wreaking environmental and economics etc….

32. Why is GMO bad for the environment ?
 GMO crops not improved yields, they have vastly increased
the use of Glyphosate …
Glyphosate use is not only bad for farmers health, its also
bad for the environment, especially for certain birds, insects
and other wildlife.

33. Herbicide resistance management :
 Diagnose various herbicide resistant weeds
 Monitoring of their nature, distribution & abundance
(Beckie et al., 2000)
 Managed efficiently by focusing on the ways of
reducing selection pressure for evolution of resistance.
 At present time, herbicide resistance in P. minor is the
most serious issue of Indian agriculture.
 So its management is very necessary for sustaining
wheat productivity.

34. Management of herbicide resistant populations Alternate
herbicides :
 Zero tillage
 Method of crop establishment
 Cultural practices
 Planting time
 Crop rotation
 Sowing method & seed rate
 Competitive variety
 Stale seed bed
 Soil mulch
 Fertilizer placement
 IWM (Bhullar et al., 2017)

35. Some important strategies regarding herbicide use :
 Stop use of herbicide to which resistance has developed
 Use alternative herbicides
 Herbicide mixture
 Herbicide rotation
 Herbicide selection
 Herbicide application
 Use of herbicides with short residual life

36. Assessment of risk associated with herbicide resistance
Management
options
Risk of resistance
Low Medium High
Herbicide mix or
rotation
> 2 modes of
action
2 modes of action 1 modes of action
Weed control in
cropping system
Cultural,
mechanical and
chemical
Cultural and
chemical
Chemical only
use of same mode
of action of
herbicide
1 year More than one > 3 year
Cropping system Full rotation Limited rotation No rotation
Weed infestation Low Moderate High
Herbicide
residual period
Short Intermediate Long
(Sunil et al., 2020)

37. Additional cultural practices for herbicide resistance
management :-
 Use of efficient sprayers fitted with multiple-
flat fan nozzles.
 Growing of competitive crop varieties with
closer row spacing.
 Use of clean seed and certified seed
 Optimization of water and nutrient management
 Follow up efficient crop rotation

38. Herbicidal mixtures for management of resistant P. minor
Herbicide Time of application Dose
(g/ha)
Pendimethalin + metribuzin Pre- emergence 1500 + 150
Mesosulfuron + iodosulfuron Post- emergence 14.4
Sulfosulfuron + metsulfuron-
methyl
Post- emergence
32
Pinoxaden + metsulfuron-
methyl
Post- emergence
64
Pendimethalin fb mesosulfuron
+ iodosulfuron
Pre- emergence fb
Post- emergence 1500/14.4
Pendimethalin fb sulfosulfuron +
metsulfuron- methyl
Pre- emergence fb
Post- emergence 1500/32
Pendimethalin fb pinoxaden +
metsulfuron methyl
Pre- emergence fb
Post- emergence 1500/64
(Kaur et al., 2019)

39. Current management strategies for mgt of P. minor & other weeds
in wheat in INDIA
1.Chemical - Pre –emergence
Early post- emergence
post emergene
Seq. apply PE &POE
2. Cultural - Zero Tillage
Agronomic Intervensions
3. Mechanical - Bed planting
4. IWM - All above methods integrated
(Bullar et al., 2017)

40. Prevention & management strategies for herbicide
resistant weed biotypes :- (NCWSS)
 Only use herbicides when necessary
 Rotate herbicides (site of action)
 Apply herbicides that includes multiple sites of action
 Rotate crops, particularly those with different life cycle
 Avoid more than two consecutive herbicide
applications with herbicide –resistant crops
 Include mechanical weed control practices
 Consider primary tillage
 Regularly scout fields to identify the weeds present
 Clean tillage & harvest equipment
 Encourage others to adopt prevention management
strategies.

41. Ten ways to beat and prevent Super weeds :
1. Monitor wind speed
2. Monitor weed growth
3. Pre- Emergence Residual Hericides
4. Get Sneaky
5. Follow label instructions
6. Cover crops
7. Stop waiting
8. 2,4-D Improvements
9. Roundup Ready Xtend
10. Enlist Duo

42. Conclusion :
 Serious issue
 Main reason behind this problem is excess use of highly efficient
herbicides with single site of action.
 Proper knowledge
 Herbicide mixtures and sequence, herbicide rotations are best
management measure to tackle the problem of resistance.
 Several other practices like alternate cultivation and fallows, use
molecular biology and biochemistry are also helpful in avoiding
herbicide resistance.
 Field demonstration programs should be conducted to provide
information to farmers about improved spraying technologies.