scbi360 envi science part 2 ipm file9/15/15 1 environmentalscience(scbi360)...
TRANSCRIPT
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Environmental Science (SCBI 360) Chemical controls and IPM
Dr. Patompong Saengwilai SC2-‐306; [email protected]
What happened?
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Crinkling Leaf takes on a crinkled texture. Usually associated with viruses or toxic effects of saliva from homopterous insects.
Crinkling may occur throughout the leaf (leC) or may be confined to edges (right).
Cupping and Curling Leaves cup up or down or they curl inward from the edges.
Downward cupping along main vein of each leaflet in soybeans caused by Bean Common Mosaic Potyvirus
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Edge Feeding Leaves chewed and eaten from the edges. Feeding lesions can have smooth or jagged edges. Usually caused by insects w/chewing mouthparts.
Leaf edge feeding on rhododendron leaves by adult black vine root weevils.
Hole Feeding Leaves have holes chewed through them. Caused by insects w/chewing mouthparts.
Yellow poplar weevil adult feeding on yellow poplar
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Mines Caused by small, immature beetles or flies that live in-‐between the upper and lower leaf surfaces. The shape of the mine, along with the plant species being aTacked, is useful in idenUfying the pest species involved.
Frass-‐linear leaf mine on birch leaf. Mines come in many shapes.
SkeletonizaLon Leaf Ussue between the veins is removed but the veins remain intact leaving a skeleton-‐like appearance.
Lindin leaf skeletonized by Japanese beetle. Note that the distal leaf Ussue is relaUvely normal looking indicaUng that the leaf veins are fully funcUonal.
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Galls
Western gall rust on Ponderosa pine branch
Soybean roots with galls from root knot nematode (right) vs. healthy root (leC).
Galls on oak leaves from cynipid wasps
Olive knot gall (caused by Pseudmomonas bacteria) on olive main trunk
Can occur on all Lssues; leaves, stems/trunks, branches, roots, etc.
Ash flower galls caused by a mite
Many insects, such as the squash vine borer feed on xylem Ussue.
Tomato wilt is caused by fungi in the genus Fusarium which plugs xylem Ussue prevenUng water/mineral transport.
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Phytophthora root rot on alfalfa (leC); Fusarium root rot on soybean (right)
Bark beetle gallery (right): The adult Beetle lays a line of eggs along a gallery. The grubs hatch, eat phloem Ussue unUl they mature.
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Thistle Weeds Amaranth
Pigweed
Nematode
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Chemical Controls
Chemical controls are pesUcides that are either naturally derived or synthesized. PesUcides oCen play a key role in pest management programs
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Chemical Controls
A pesLcide is defined as any material that is applied to plants, the soil, water, harvested crops, structures, clothing and furnishings, or animals to kill, aTract, repel, regulate or interrupt the growth and maUng of pests, or to regulate plant growth. PesUcides include a wide assortment of chemicals with specialized names and funcUons.
Classified by pests Ø Avicides control pest birds. Ø Bactericides control bacteria. Ø Disinfectants (anLmicrobials) control microorganisms. Ø Fungicides control fungi. Ø Herbicides control weeds and other undesirable plants. Ø InsecLcides control insects and related arthropods. Ø MiLcides (acaricides) control mites. Ø Molluscicides control snails and slugs. Ø NemaLcides control nematodes (roundworms). Ø Predacides control predatory vertebrates. Ø Piscicides control pest fish. Ø Repellents repel insects, related invertebrates, birds, and mammals. Ø RodenLcides control rodents. Ø Defoliants cause leaves or foliage to drop from plants. Ø Desiccants promote drying or loss of moisture from plant Ussues. Ø Growth regulators are substances (other than ferUlizers or food) that alter
growth and development of plants and animals
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Systemic VS Contact
PesLcides
1. Organophosphate -‐ Cholinesterase inhibitors -‐ Most organophosphates are insecUcides. -‐ They were developed during the early 19th century, but their effects on insects, which are similar to their effects on humans, were discovered in 1932.
-‐ Some are very poisonous. However, they usually are not persistent in the environment.
e.g. Chlorpyrifos, malathione, and dimethoate
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2. Carbamate pesLcides -‐ Cholinesterase inhibitors -‐ The enzyme effects are usually reversible. e.g. Sevin, Baygon
3. Organochlorine insecLcides -‐ They were commonly used in the past, but many have been
removed from the market due to their health and environmental effects and their persistence
e.g., DDT, aldrin, dieldrin, and chlordane).
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DDT -‐ Dichlorodiphenyltrichloroethane -‐ Colorless, tasteless, almost odorless -‐ InsecUcides by opening sodium ion
channels in neurons. -‐ Muller was awarded the Nobel prize
in Physiology or Medicine in 1948 -‐ Persistent organic pollutant.
DDT
DDE DDD
DDT
DDE cause eggshell thinning as resulted in severe populaUon decline in mulUple North American and European bird of prey species
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Silent Spring
4. Pyrethroid pesLcides -‐ They were developed as a syntheUc version of the naturally
occurring pesUcide pyrethrin, which is found in chrysanthemums. -‐ They have been modified to increase their stability in the
environment. -‐ Highly toxic to fish and other aquaUc animals -‐ Commonly adsorbed to organic material of sediments
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Herbicides Paraquat: -‐ N,Nʹ′-‐dimethyl-‐4,4ʹ′-‐bipyridinium dichloride, -‐ Widely used -‐ Kill weeds on contact -‐ Linked to development of Parkinson‘s disease
Glyphosate: -‐ N-‐(phosphonomethyle)glycine -‐ Roundup (Monsanto) -‐ Inhibit enzyme involved in the synthesis of tyrosine,
tryptophan, and phenylalanine.
Herbicides 2-‐4-‐D -‐ 2,4-‐dichlorophenoxyaceUc acid -‐ Systemic herbicide controlling broadleaf weeds -‐ SyntheUc auxin – absorbed through leaves and
translocated to meristem à uncontrolled growth
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Integrated Pest Management (IPM)
Intergrated Pest Management (IPM)
Integrated: a focus on interacUons of pests, crops, the environment, and various control methods. This approach considers all available tacUcs and how these tacUcs fit with other agricultural pracUces used. Pest: an organism that conflicts with our profit, health, or convenience. If a species does not exist in numbers that seriously affect these factors, it is not considered a pest. Management: a way to keep pests below the levels where they can cause economic damage. Management does not mean eradicaUng pests. It means finding tacUcs that are effecUve and economical, and that keep environmental damage to a minimum.
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Intergrated Pest Management (IPM)
IPM is managing crop using many tacUcs to keep pest levels below an economic threshold.
Why have pest managers shiCed to IPM when chemical pesUcides so oCen succeed at
controlling pests?
IPM helps to keep a balanced ecosystem.
-‐ Every ecosystem has a balance; the acUons of one kind of organism in the ecosystem usually affect other species.
-‐ Introducing chemicals into the ecosystem can change this balance, destroying certain species and allowing other species (someUmes pests themselves) to dominate.
-‐ PesUcides can kill beneficial insects that consume pests, leaving few natural mechanisms of pest control.
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PesLcides can be ineffecLve.
-‐ Chemical pesUcides are not always effecUve. Pests can become resistant to pesUcides.
-‐ In fact, some 600 cases of pests developing pesUcide resistance have been documented to date, including many common weeds, insects, and disease-‐causing fungi. Furthermore, pests may survive in situaUons where the chemical does not reach pests, is washed off, is applied at an improper rate, or is applied at an improper life stage of the pest.
IPM can save money. -‐ IPM can avoid crop loss caused by pests and prevent
unnecessary pesUcide expense.
-‐ Applicators can save on pesUcide costs because the need for control, rather than rouUne applicaUon triggered by the calendar, is the basis for applying pesUcides.
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IPM promotes a healthy environment. -‐ We have much to learn about the persistence of
chemicals in the environment and their effect on living creatures.
-‐ Cases of contaminated groundwater appear each year, and disposal of containers and unused pesUcides sUll pose challenges for applicators. Make sure that environmental impacts are considered in any pest management decisions. Using IPM strategies helps keep adverse effects to a minimum.
Three components of IPM
1) idenUfying and monitoring pest problems; 2) selecUng the best pest management tacUcs; 3) recordkeeping and evaluaUng the program.
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TacLcs
Understand the life cycle and habits of the pest. Some control methods will work only if they are used at the right Ume. Decide whether the infestaUon is serious in terms of economic loss. Compare the costs and benefits of various control methods. Make plans for the future. Not every part of an IPM program can be put into effect immediately. Some tacUcs, such as planUng resistant varieUes or rotaUng crops, require long-‐range planning.
Economical concepts
Economic damage (ED) occurs when the cost of preventable crop damage exceeds the cost of control.
Economic injury level (EIL) is the lowest pest populaUon that will cause economic damage. For many pests it is important to use control measures before this level is reached.
Economic threshold (ET) is the pest populaUon level at which a control tacUc should be started to keep the pest populaUon from reaching the EIL.
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Economical concepts
Pest Management approach
PrevenLon PrevenUon includes such things as planUng weed-‐ and disease-‐free seed and growing varieUes of plants resistant to diseases or insects, sanitaUon, using cultural controls to prevent weedy plants from seeding, and choosing planUng or harvesUng Umes that minimize pest problems. PesUcides are someUmes used for pest prevenUon as well.
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Pest Management approach Suppression Suppressive pest-‐control methods are used to reduce pest populaUon levels. The methods chosen usually do not eliminate all pests, but reduce their populaUons to a tolerable level or to a point below an economic injury level
Pest Management approach
EradicaLon EradicaUon is the total eliminaUon of a pest from a designated area. Over larger areas eradicaUon may be very expensive and oCen has limited success. Large eradicaUon programs are usually directed at exoUc or introduced pests posing an immediate area-‐wide public health or economic threat.
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Pest management methods
-‐ When implemenUng the IPM program, try to select the methods that are the most effecUve and the least harmful to people and the environment.
-‐ Use several methods whenever possible, and be sure to use them correctly.
1) Mechanical Control Mechanical control involves the use of devices, machines, and other physical methods to control pests or alter their environment. Traps, screens, barriers, fences, and nets are examples of devices used to prevent pest acUvity or remove pests from an area.
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CulLvaLon
CulUvaUon is one of the most important methods of controlling weeds. It is also used for some insects and other soil-‐inhabiUng pests. Devices such as plows, disks, mowers, culUvators, and bed condiUoners physically destroy weeds or control their growth and disrupt soil condiUons suitable for the survival of some microorganisms and insects.
Cultural Control The goal of cultural control is to alter the environment, the condiUon of the host, or the behavior of the pest to prevent or suppress an infestaUon. It disrupts the normal relaUonship between the pest and the host and makes the pest less likely to survive, grow, or reproduce. e.g.Weeds can be managed by mulching (with plasUc, straw, shredded bark, or wood chips) and by using cover crops.
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Biological Control
Biological control is oCen directed against pests that are not naUve to a geographical area. Introduced pests oCen cause problems in their new locaUons because they lack natural enemies to help control them.
Trichoderma
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ParasiLc wasps
In 2009 mealybugs had spread to more than 700 square miles (200,000 hectares) of eastern and northeastern Thailand, where the pests are known to kill up to half of the plants in a given field
Anagyrus lopezi wasp
Like the wasp and cassava, the Phenacoccus maniho7 mealybug is naUve to the South American country of Paraguay.
Weevils
The biological control of waterhyacinth is considered a qualified success. Waterhyacinth infestaUon in Florida was esUmated to be only 2600 acres in 1989. Although this figure was obtained aCer herbicide treatment of 25,000 acres, earlier herbicide treatment of more acreage had not reduced the infested area.
Neoche7na bruchi
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Ladybugs
BiopesLcides Microbial pesLcides consist of a microorganism e.g., a bacterium, fungus, virus, or protozoan as the acUve ingredient. Microbial pesUcides can control many different kinds of pests, although each separate acUve ingredient is relaUvely specific for its target pest. The most widely used microbial pesUcides are subspecies and strains of Bacillus thuringiensis, or Bt. Each strain of this bacterium produces a different mix of proteins, and specifically kills one or a few related species of insect larvae. While some Bt's control moth larvae found on plants, other Bt's are specific for larvae of flies and mosquitoes. The target insect species are determined by whether the parUcular Bt produces a protein that can bind to a larval gut receptor, thereby causing the insect larvae to starve. Plant-‐Incorporated-‐Protectants (PIPs) are pesUcidal substances that plants produce from geneUc material that has been added to the plant. For example, scienUsts can take the gene for the Bt pesUcidal protein, and introduce the gene into the plant's own geneUc material. Then the plant, instead of the Bt bacterium, manufactures the substance that destroys the pest. Biochemical pesLcides are naturally occurring substances that control pests by non-‐toxic mechanisms. ConvenUonal pesUcides, by contrast, are, in general, syntheUc materials that directly kill or inacUvate the pest. Biochemical pesUcides include substances, such as insect sex pheromones, that interfere with maUng, as well as various scented plant extracts that aTract insect pests to traps.