Transcript Pests of Field Crops - University of Wyoming

PESTICIDE SAFETY AND APPLICATION
PLNT 1150
Alex Latchininsky
Assistant Professor / Extension Entomologist
Dept. of Renewable Resources
January 2006
DISCLAIMER
Trade or brand names used in this
presentation are used only for
educational purposes
The information given herein is
supplied with the understanding that
no discrimination is intended, and no
endorsement information of products
is implied
I. PRINCIPLES OF FIELD
CROP INSECT CONTROL
You must know…
• Basics of insect classification and biology
• Crop value
• Preventive measures
• What’s new?
II. WHAT CAUSES
INSECT OUTBREAK?
It can be weather, but…
… Frequently it’s
our own fault …
• Large-scale monocultures
• Poor cultural practices
• Overuse of insecticides
(killing natural enemies)
• Pest introduction in the new
environment
• Disruption of a natural
equilibrium
III. TYPES OF CONTROL
1. Biological
• Introduction of exotic species of parasites and
predators
• Conservation of parasites and predators
• Augmentation of parasites and predators
• Microbiological control (pathogens)
Drawbacks: may be costly;
often slow and weather-dependent
Biocontrol agents
Ladybird beetle larva and adult
Pathogens
TYPES OF CONTROL
2. Mechanical
• Hand picking
• Trapping
• Using devices like screens and
barriers
Drawbacks: time- and labor-consuming,
slow, often impractical at large-scale
TYPES OF CONTROL
3. Cultural
• Crop rotation – good for insects with long life cycles
(e.g., corn rootworms)
• Trap crops – attracts pests; then the trap crop is
destroyed or treated with insecticide
• Tillage – good for soil-inhabiting insects
• Clean culture – removal of crop residues
• Timing of planting and harvesting
• Resistant plant varieties, including genetically modified
cultivars
Cultural control: advantages
• Normal farming practices, making
environments unfavorable for pests
• Preventive strategy
• Economical
• Good for low-unit-value crops
Cultural control: drawbacks
• Will not work in an outbreak situation
when pest infestation is heavy
TYPES OF CONTROL
4. Chemical
Reduction of insect populations or
prevention of insect injury by the use of
materials to poison them, attract them to
other devices, or repel them from specific
areas
Still our first line of defense despite adverse publicity
Chemical control: advantages
• Efficient
• Economical
• Fast-acting
• Easy to use
• Generally safe
Chemical control: drawbacks
• Temporary relief
• May cause resistance
• Residues in harvest
• Environment: side-effects to non-targets
• Some insecticides have direct hazards
TYPES OF CONTROL
5. Integrated (IPM)
Management of insect populations by the
utilization of all suitable techniques in a
compatible manner so that damage is kept
below economic levels
Ecological approach to avoid economic losses and to
minimize adverse effects
IV. MAJOR
FIELD CROP
PESTS
Western Corn Rootworm
Northern Corn Rootworm
Southern Corn Rootworm
Spider (Banks grass) mites
Western Corn Rootworm
adult
larva
Diabrotica virgifera - beetle
• The larvae attack the roots, causing the plants to fall
over and become goose-necked.
• The adults feed on the silks and, at times, become so
numerous that pollination cannot occur.
• Overwinter as eggs in the soil. One generation per year.
Western Corn Rootworm
Control
• The most effective means of control
is by crop rotation. Corn grown year
after year on heavy soil is the most
seriously damaged.
• Pesticides: do not use when
rotating crops. If necessary, apply
granules in a 6-7 inch bank over the
row at planting time or as a
cultivation treatment.
Heavy root damage
• Do not apply sprays for adults
unless pollination is threatened.
Northern Corn Rootworm
• Yellowish-green 3/16
to 1/4 inch (5 to 6 mm)
long, slightly smaller
than the western and
southern corn
rootworms.
• There are no markings
on the elytra.
Diabrotica barberi - beetle
• Adults are found on the silks of corn. Like the western corn
rootworm, this species overwinter as eggs, which are deposited in
cornfields. The adults are common on goldenrod flowers.
• Control: Similar to Western corn rootworm.
Southern Corn Rootworm
Diabrotica undecimpunctata - beetle
• Pale greenish-yellow
beetle with six black
spots on each wing
cover.
• Slightly bigger than
WCRW and NCRW.
• Occurs commonly on
cucumber, melon vines,
corn silk, weeds, and in
alfalfa fields.
Damage: The larvae damage roots of
corn and winter rye, and adults eat holes
in melon foliage. Adults spread bacterial
wilt to cucumbers.
• Overwinter as adults.
May have two or more
annual generations.
Control: Similar to WCRW and NCRW.
• Other name: spotted
cucumber beetle.
Spider mites
Size: <1/32”
8 legs
Twospotted spider mites
Tetranychus urticae
Banks grass mites
Oligonychus pratensis
• Overwinter as adults in debris. Several generations per year.
• Damage: pierce plant cells and suck out liquid contents. Leaves
develop chlorotic spots and may die back. Start feeding on the lower
leaves and move upward. Hot, dry conditions are favorable.
• Control: systemic insecticides.
Alfalfa weevil
Pea aphid
Lygus bug
Blister beetles
Alfalfa weevil
Hypera postica - beetle
• The color is brown with a darker brown stripe down the middle of the elytra.
• The pronotum has a dark brown stripe through which runs a pale line.
• Adult length is about 1/4 inch (6 mm).
Alfalfa weevil
Eggs
Larvae
• Larva is green or yellow with dark head.
• Damage: mostly by larvae. Skeletonize leaves. Feed on the
foliage, especially terminal leaf buds, then drop to the
ground and pupate in the litter.
• Adults overwinter. One generation per year.
Alfalfa weevil
Leaf skeletonization
by larvae
• Cultural management: Early first harvest; fall grazing; spring
burning; resistant cultivars.
• Chemical control: Mostly organophosphates, which are highly
toxic for pollinators (bees) and other beneficials. Apply
early in the morning or late in the evening.
Pea aphid
Acyrthosiphon pisum
• Green, long-legged, about 1/6” long.
• Many generations per year.
• Overwinter as eggs or adult females.
Pea aphid
• Damage: Suck the sap. Cause wilting and reduce
quality and quantity of alfalfa hay.
• Control: preferably systemic insecticide sprays.
Apply when T>50°F early in the morning or
late in the evening to preserve the beneficials.
Lygus bug
Lygus lineolaris – true bug
• Adults:
¼” long, variable in color. Distinct “V” on
the back. Piercing-sucking beak.
• Overwinter as adults. Three generations per year.
Lygus bug
Lygus bug larvae
• Damage: Most serious in seed production. Cause buds
to die, flowers to drop, immature seeds to shrivel.
Forage production and quality also affected.
• Control: Systemic insecticides and carbaryl. Nontargets (predators, parasites and pollinators) are a
great concern. Timing of application is important.
Blister beetles
Toxic chemical cantharidin can make hay poisonous
Mexican bean beetle
Mexican bean beetle
larva
adult
Epilachna varivestis – a ladybird beetle
• Adults are red with 16 black spots, ¼” long.
• Larvae are yellow with branched spines, up to ¼” long.
• Overwinter as adults in litter. One generation per year.
Mexican bean beetle
Damage: Both adults and especially larvae chew off
portions of leaves. They usually feed by clinging
to the under surface of the leaves and eating
irregular sections of the lower leaf surface. The
upper surface of leaves quickly dries out, giving
a lace-like, skeletonized appearance.
Mexican bean beetle
Control: Cultural – burning or destruction of crop
residues; Resistant varieties (e.g., Lima beans);
Biological – several species of parasitoids available;
Chemical – systemic and non-systemic insecticides,
soil applications and foliar spray. Difficult to
control because feed underneath the leaves.
Sugar Beet Root Maggot
Beet Leafhopper
Sugar Beet Root Maggot
adult fly
larva (maggot)
Tetanops myopaeformis – a true fly
• Overwinters as a larva (maggot) in the soil.
• Adult flies emerge in May.
• Females deposit eggs around the base of sugar beet plant.
• One generation per year.
Sugar Beet Root Maggot
Damage: maggots attack seedlings and cause loss of
stand. Yields are reduced.
Control: only larval control is recommended. Apply
granules to the soil as a 4-6” band over the row.
Granules must have moisture to be activated.
Beet Leafhopper
adult
nymph
Circulifer tenellus
• Overwinter as adults in weedy areas. Host plants
include wild mustards, Russian thistle and other weeds.
• Eggs hatch and nymphs move into beet fields.
• One or more generations per year.
Beet Leafhopper
Damage: vector of the virus causing the disease curly
top in sugar beets.
Control: Cultural – Weed management. Resistant
varieties.
Chemical – granulated formulations to the soil.
Moisture is necessary to activate the granules.
Potato Psyllid
Colorado Potato Beetle
Potato Flea Beetle
Potato Psyllid
adult
nymphs
Bactericerca (=Paratrioza) cockerelli
• Related to aphids and leafhoppers. The adult has clear wings that
rest rooflike over the body. Predominantly black, with white
markings. Scale like flat nymphs. Psyllids jump quite readily when
disturbed.
• Overwinter as eggs. Several generations per year.
Potato Psyllid
Damage: nymphs inject toxin when feed causing
“psyllid yellows” and upward curling of leaves.
Control: granular systemic insecticides at planting
time. Foliar spray of synthetic pyrethroids.
Colorado Potato Beetle
Leptinotarsa decemlineata
Colorado Potato Beetle
adult and eggs
larvae
• Overwinters as an adult buried in soil.
• Eggs hatch in the spring. Larvae feed on foliage.
• One or two generations per year.
Colorado Potato Beetle
Damage: both larvae and adults are voracious feeders.
They often completely defoliate potato plants.
Control: systemics in the soil at planting time. Foliar
spray after egg hatch. Resistance may be an issue.
Potato Flea Beetle
Epitrix cucumeris
• Adult beetle is 1/16” long and black in color.
• Has enlarged hind legs and jumps vigorously when
disturbed.
• Overwinters as an adult in soil litter. One or two
generations per year.
Potato Flea Beetle
• Damage: destroys foliage. Spreads a fungal disease early potato blight.
• Control: Cultural – destruction of plant residues.
Weed control. Late planting.
• Chemical – systemic insecticides to the soil at
planting time. Foliar spray with contact
insecticides against larvae.
Pale Western Cutworm
Western Curl Mite
Russian Wheat Aphid
Greenbugs
Grasshoppers
Pale Western Cutworm
adult
Agrotis orthogonia – “miller” moth
• Eggs are laid in the soil in the fall.
• Overwinter as eggs. Hatch very early
in spring.
• One generation per year.
larva
Pale Western Cutworm
• Larvae feed mostly underground.
• Cause pruning of plants, loss of stand, and stunted
and unthrifty plants.
Wheat Curl Mite
Eriophyes tulipae
• The mites are very tiny, white, spindle-shaped, with 4
legs near the anterior end.
• Reproduce parthenogenetically (without males).
• Overwinter on grasses or volunteer wheat.
Wheat Curl Mite
Damage: Transmits a viral disease called wheat streak mosaic.
This virus can cause serious reductions in wheat crop yields. Although the
mites feed on a variety of grasses, wheat is the preferred host and high
populations can develop during the summer and fall on volunteer wheat.
Control: Cultural - prevent the growth of volunteer wheat. Late planting.
Resistant cultivars. Chemicals are rarely effective.
Hail belt areas are in greatest need of protection.
Russian Wheat Aphid
Diuraphis noxia
• Native to southern Russia and the Mediterranean region.
• Introduced in the U.S. in 1986.
• Reproduces sexually or asexually.
• Several generations per year.
• Overwinter as immatures or adults in grasses.
Russian Wheat Aphid
Soybean Aphid
Russian Wheat Aphid identification
characteristics
• Elongated
• Short antennae
• No cornicles (“tail-pipes”)
• Forked (double) tail
Russian Wheat Aphid
Damage:
• RWA initiates feeding at the base of the leaves near the top of the plant. It injects a
toxic saliva into the plant. The edges of the leaf curl inward protecting the pest.
• Plants become purplish and leaves develop longitudinal yellowish and whitish streaks.
• Tillers of heavily infested plants run parallel to the ground (a prostrate appearance).
• Heads are distorted.
Russian Wheat Aphid
Control:
• Cultural – control volunteer wheat; avoid early
planting; use resistant varieties; maintain
healthy stand.
• Biological – parasitic wasps, ladybird beetles.
• Chemical – foliar sprays with systemics.
Greenbug aphids
Inject toxin when feed. Cause “greenbug spots.”
Control: systemic insecticides.
Grasshoppers in the West
• economically important in 17 western states
• a dozen pest species (out of >450)
• annually remove 20-22% of rangeland vegetation
• estimated average loss $400 million per year
• forage losses in 2000 in Texas: $190 million
2005
Rangeland
Grasshopper
Hazard Map
Based on adult
Survey 2004
Grasshoppers
112 species in Wyoming; only ~10 are serious pests
Differential
Migratory
Twostriped 
Twostriped 
Mormon cricket
is neither a grasshopper nor a cricket – it’s a katydid
Anabrus simplex
Grasshoppers in Wyoming
• require vast areas to be chemically treated
(up to 20 million ac per year during outbreaks)
• 400,000 acres protected in 2003 in Wyoming
(Niobrara, Goshen, Platte and other counties)
• Reduced Agent and Area Treatments - RAATs
Grasshopper Outbreak Frequency 1944-1996
2005
Rangeland
Grasshopper
Wyoming
Hazard Map
Based on adult
Survey 2004
LIFE
CYCLE
V
IV
Duration of
nymphal
period:
~ 30-40 d
III
II
I
1st instar critical stage
for GH
survival
(up to >90%
mortality)
Grasshopper Treatment
Application Strategies
Conventional/Blanket
RAATs
THE RAATs CONCEPT
• Hoppers killed directly in the treated swaths
• More predacious insects and parasitoids
survive treatment
• Hoppers move into treated strips and die
• Birds continue to feed on hoppers
• Less disruption to bio-control agents of
weeds (APHIS data on Aphthona spp.
beetles on leafy spurge in Montana)
ATV- RAATs
Boom Buster nozzles
S.S. Co. ¼-KLC- 5 Fieldjet nozzles
•Half rate of “Boomless”
type @ 2 Qt/min
•Low cost and simplicity
•17-21 ft swath
RAATs
untreated
treated
Aerial
100 ft 100 ft
ATV
Malathion
(Fyfanon®)
Organophosphate; neurotoxin (AcChE inhibitor)
PROS:
Low cost/unit
ULV logistics
Reliable results
Familiar product (since 1965)
CONS:
Hot weather; rain
Low residual (no RAATs)
Non-target effects
Harm to people and planes
Organophosphates – phasing out
Carbaryl (Sevin® XLR Plus)
Carbamate; neurotoxin (AcChE inhibitor)
PROS:
Temperature Range
Some Residual (RAATs)
Reliable Results
Easy Handling (water based)
Familiar product (since 1979)
CONS:
Higher Volume
Non-target effects
Harm to people
Diflubenzuron (Dimilin® 2L)
Benzoyl-Urea; IGR (chitin synthesis inhibitor)
PROS:
Safety (bees, people, etc.)
Residual (RAATs)
Reliable Results
Temperature Range
CONS:
Timing!!! (IGR = nymphs)
Less Familiar (since …)
High Cost/unit
Harm to aquatic invertebrates – R.U.P.
MOLT
Insects are killed when
they grow to a next
developmental stage
TIMING
V
ineffective
is critical
when
applying
Dimilin
not recommended
IV
III
II
I
recommended
Risks for Different Groups
of Non-target Organisms
Source: Food and Agriculture Organization of the UN, 2003
Environmental Profile
Carbaryl
CAR
Malathion
OP
Diflubenzuron
BU (IGR)
Human toxicity
(WHO/EPA class)
II (Moder.)
III (Low)
Unlikely to be toxic
Fish toxicity
Moderate
Low
Low
Aquatic invertebrate
toxicity
Low
Moderate
High
Mammalian toxicity
Moderate
Low
Low
Toxicity for birds and
reptiles
Low
Moderate
Low
Toxicity for honey bee
High
High
Low
Toxicity for other
non-target arthr.
High
Moderate
Moderate
RAATs vs. Standard:
Efficacy
Control is 5 to 15% lower
than conventional blanket methods
(usually about 80% kill)
It costs a lot to kill them all.
Surviving grasshoppers provide a prey base for the
predators.
We haven’t observed any resurgence the following year in
treated areas.
RAATs COSTS
50-60% less than
the standard treatment
about $1.50 / acre protected
Other Options
Carbaryl bran baits
Pros: Target specificity
Operator safety
Enhanced formulations
Cons: Application logistics and cost
Species constraints (not all species take them)
Adverse conditions
Systemics applied in the furrow at planting
RAATs – the preferred option for USDA
grasshopper treatments in recent EIS
Decision-Support software
2005:
Crop protection
module added
CARMA can be downloaded from Grasshoppers of Wyoming and the West at:
www.wygisc.uwyo.edu/grasshopper/
or request a free CD-ROM Grasshoppers: Their Biology, Identification
and Management from:
www.sidney.ars.usda.gov/grasshopper/
Pest Control in Wyoming:
Fine trophies guaranteed!
Come catch the Entomology
Short Course, 2006
February 1-3, 2006
• What will be covered?
General Entomology, Insect Identification,
Arachnids, Grasshopper Management, Biological Control, Mosquitoes, RS-GIS and more.
• When is it?
February 1st, 2nd, and 3rd, 2006. We will begin at 1 PM on the first
day, go from 8 to 5 the second day and release you at noon on the third day.
• Where is it? College of Agriculture Building, 13th & Lewis St., University of
Wyoming, Laramie, WY.
• Who teaches it? Dr. Alex Latchininsky & Scott Schell, UW-CES Extension
Entomologists. Plus guest lectures by other experts in their fields.
You will get two books, a course packet, and 2 hours of
college credit for as little as a $100 (maybe less)
Questions?
Contact Alex Latchininsky or Scott Schell,
Uwyo Extension Entomologists
Phone 766-2298 or 766-2508
Email: [email protected] or [email protected]
http://uwadmnweb.uwyo.edu/UWCES/Entomology.asp