Pesticides are substances used to control pests and are classified in several ways, including by chemical class, target organism, and mode of action. Common pesticides target weeds, insects, fungi, or other pests. They work through various modes of action such as inhibiting amino acid biosynthesis, lipid biosynthesis, or photosynthesis. Proper application timing and techniques are important to maximize effectiveness while minimizing harm to non-target species. Pesticide resistance can develop if pest populations are not properly managed.
Biopesticide (2).pptx .This slides helps to know the different types of biop...
pesticides
1.
2. Pesticides Defined: Any substance or
mixture of substances, intended for
preventing, destroying, or mitigating any
pest, or intended for use as a plant
growth regulator, defoliant or desiccant.
(FIFRA)
Technically includes biocontrols and
plants bred for pest resistance. Common
usage excludes these.
3. Pesticides are commonly classified several
ways:
Chemical class -- Increasingly diverse
Target Organism
Mode of Action
Application timing or usage
6. Broad Spectrum -- Kills broad range of pests, usually refers to
insecticides, fungicides, and bactericides
Contact Poison -- Kills by contacting pest
Disinfectant (Eradicant) -- Effective against pathogen that has already
infected the crop
Germination Inhibitor -- Inhibits germination of weed seeds, fungus
spores, bacterial spores.
Nonselective -- Kills broad range of pests and/or crop plants, usually
used in reference to herbicides
Nerve Poison -- Interferes with nervous system function
Protectants -- Protects crop if applied before pathogens infect the crop
Repellents -- Repels pest from crop or interferes with pest’s ability to
locate crop
Systemic -- Absorbed and translocated throughout the plant to provide
protection
Stomach Poison -- Kills after ingestion by an animal
7. Annual Crops
Seed Treatment -- Pesticide coats or is absorbed into the seed.
Pre-Plant -- Pesticide applied any time before planting
At-Planting -- Pesticide applied during the planting operation
In-Furrow -- In the planting row, direct contact with crop seed
Side-Dress -- Next to the row, no direct contact with crop seed
Broadcast -- Distributed over the soil surface.
Pre-Emergent -- Before the crop has emerged from the ground
Post-Emergent -- After the crop has emerged from the ground
Lay-By -- Final operation before harvest sequence
Perennial Crops
Dormant -- Applied during winter dormancy
Bud Break -- Applied as dormancy is broken
Harvest-Related Timing
Pre-Harvest -- Just before crop is harvested
Post-Harvest -- After crop is harvested
8. Inexpensive
Greater control confidence
Effective and rapid
Therapeutic
Management efficiency
Can enable other management practices
9. Greater human health threat
Greater environmental cost
Detrimental effects on non-target species
• Those useful in the CPS
• Those useful outside the CPS
• Those with no established uses
Interferes with other aspects of IPM
• Secondary pests
• Re-entry Intervals & scouting
• Limits other control options
Less sustainable
10. Pest complex – Some require pesticides
• Multiple, simultaneous species in same group
• At least one species that causes excessive
damage at low density
• Important species new/poorly understood
• Key pest(s) lacking control alternatives
• Key pest(s) especially vulnerable to pesticide
placement/timing
11.
12. Better understanding of how herbicides
perform
Improve herbicides performance
Diagnosing herbicide injury
Prevent and manage herbicide resistance
14. Use herbicides to achieve your goal
• Reduce the impact of invasive species
• Secure the presence of targeted species
But not all herbicides are equal!
15. Selective: controls or suppresses one
species of plant without seriously
affecting the growth of another plant
species
2,4-D
Nonselective: control plants regardless
of species
Roundup
17. Commercial Products (Roundup, Durango)
Mode of Action
(Amino Acid Biosynthesis Inhibitors)
Site of Action (EPSPS inhibitor)
Chemical Family (Glyicines)
Active Ingredient (Glyphosate)
18. Sequence of events from
absorption of the herbicide
into the plant until the plant
dies
21. Synthetic auxins (regulate plant growth)
Affect several plant processes such as
cell division, cell enlargement, protein
synthesis and respiration
Act by upsetting the normal hormonal
balance in plants
22. Herbicide uptake is primarily through
the foliage but root uptake is possible
Translocate in both xylem and phloem
Effective on perennial and annual
broadleaf weeds
Selectively kill broadleaf plants
• Injury may occur in grasses
23. Chemical Family Common Name Trade Name
Phenoxy acetic acids 2,4-D 2,4-D, Campaign,
Crossbow,
Landmaster BW,
others
2,4-DB Butyrac
MCPA MCPA, others
Benzoic acid dicamba Banvel, Clarity
pyridines clopyralid Curtail, Transline
fluroxypyr Starane
picloram Tordon
Examples of PGR
24. Parallel veination due to 2,4-D
Photo: HMOA and Crop Injury Symptoms.
Univ. of Minnesota Extension
25. Leaf cupping caused by dicamba
Photo: HMOA and Crop Injury Symptoms.
Univ. of Minnesota Extension
27. Tordon runoff into soybean fieldTordon runoff into soybean field
Photo: Kansas State University Extension
28. Prevent synthesis of certain amino acids
produced by plants but not animals
Excellent foliar and root absorption
Broad weed spectrum
Translocates to shoot and root new growth in
both xylem and phloem
Plants stop growing shortly after application
Plant death may be slow (10 days+)
29. Chemical Family Common Name Trade Name
Sulfonylureas chlorsulfuron Glean, Telar
thifensulfuron Harmony GT
nicosulfuron Accent
Imidazolinones imazamethabenz Assert
imazapic Plateau
imazamox Raptor
Amino acid derivates glyphopste Roundup, Glyphomax,
Rodeo, and others
Examples of Amino Acid Synthesis Inhibitors
33. Tightly adsorbed and inactive in soil
Phloem translocated
Inhibits EPSP enzyme responsible for
production of aromatic amino acids
phenylalinine, tyrosine and tryptophan
Very nontoxic
38. Control annual or perennial grasses or broadleaves
Shut down the photosynthetic process
Slow starvation of the plant
However, the plant experiences a more rapid death
be due to the production of secondary toxic
substances
Injury symptoms: yellowing (chlorosis) of leaf
tissue followed by death (necrosis) of the tissue
39. Controls big sage, shinnery and
other oaks, tarbush and
creosote bush
Sagebrush thinning and brush
sculpting programs
Rangeland, pastures, clearings
for wildlife and other non-
cropland areas
tebuthiuron
40. Injury symptoms:
Only occur after the cotyledons and first leaves emerge
(do not prevent seedlings from germinating or emerging)
yellowing (chlorosis) of leaf tissue followed by death
(necrosis) of the tissue
Older and larger leaves affected first: they take up
more of the herbicide-water solution as they are the
primary photosynthetic tissue of the plant
42. Postemergence contact herbicides
Little soil activity
Activated by exposure to sunlight to form oxygen
compounds such as hydrogen peroxide
These oxygen compounds destroy plant tissue by
rupturing plant cell membranes
Perennial weeds usually regrow because there is
no herbicide movement to underground root or
shoot systems
43. Controls weeds in just 24 to 48
hours
Broad-spectrum and non-
selective control of grasses,
broadleaf weeds and sedges
Cheatgrass, kochia, Russian
thistle, annual mustards
No residual effect
46. Better understanding of how herbicides
perform
Improve herbicides performance
Diagnosing herbicide injury
Prevent and manage herbicide resistance
47. Herbicide Resistance is NOT due to:
1. Sprayer skips or plugged nozzles
2. Weather problems that cause poor
control
3. Plants that are ‘naturally tolerant’ to the herbicide
4. Genetic changes caused by the herbicide
48. Herbicide Resistance is:
The ability of a plant to survive and
reproduce after treatment with a dose of
herbicide that would normally kill the plant
Banvel-resistant
kochia
49. Where do Resistant Weeds
Come From?
One in one million, billion, trillion….?
It’s all about selection…..
50. Selection intensity
• Herbicide efficacy
• Length of soil residual period
• Number of herbicide applications / year