Pastures & Rangeland: Insect Pests & Insecticides Alan H. Roe Insect Diagnostician Plant Pest...
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Transcript of Pastures & Rangeland: Insect Pests & Insecticides Alan H. Roe Insect Diagnostician Plant Pest...
![Page 1: Pastures & Rangeland: Insect Pests & Insecticides Alan H. Roe Insect Diagnostician Plant Pest Diagnostic Lab Utah State University.](https://reader033.fdocuments.net/reader033/viewer/2022042814/551a6687550346b52d8b4b04/html5/thumbnails/1.jpg)
Pastures & Rangeland:Insect Pests & Insecticides
Alan H. Roe
Insect Diagnostician
Plant Pest Diagnostic Lab
Utah State University
![Page 2: Pastures & Rangeland: Insect Pests & Insecticides Alan H. Roe Insect Diagnostician Plant Pest Diagnostic Lab Utah State University.](https://reader033.fdocuments.net/reader033/viewer/2022042814/551a6687550346b52d8b4b04/html5/thumbnails/2.jpg)
Part I: Common Insect Pests of Pastures and Rangeland
Part II: Insecticides for Pastures and Rangeland
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Common Insects Submitted from Pasture & Rangeland
• Army cutworm, Euxoa auxiliaris
• Armyworm, Pseudaletia unipuncta
• Black grass bugs, Labops & Irbisia
• Cereal leaf beetle, Oulema melanopus
• Grasshoppers, Melanoplus & Camnula
• Mormon cricket, Anabrus simplex
![Page 4: Pastures & Rangeland: Insect Pests & Insecticides Alan H. Roe Insect Diagnostician Plant Pest Diagnostic Lab Utah State University.](https://reader033.fdocuments.net/reader033/viewer/2022042814/551a6687550346b52d8b4b04/html5/thumbnails/4.jpg)
Army Cutworm, Euxoa auxiliaris
• Feeds on a wide variety of crops including small grains, grasses, corn, alfalfa
• Prefers broadleaf weeds e.g. mustards
• Overwinters as partially grown larva
• Larvae emerge in spring; active March to mid-May
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Army Cutworm• Moths emerge in May-June, lay eggs in fall• Early larvae begin feeding, then hibernate• One generation per year• Threshold in wheat: 4 or more per sq. ft.;
2 or more per sq. ft. if stressed• Hides in the daytime; check around plants
and under debris
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Armyworm, Pseudaletia unipuncta
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Armyworm• Hosts include corn, small grains, alfalfa,
clover, sorghum, sugar beets, other grasses
• Overwinter in larval or pupal stage
• Mild winter with cool spring favors survival
• Appear suddenly in spring, feed at night
• Feed 3-4 weeks, then pupate in soil
• Up to 3 generations per year
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Armyworm
• Larvae submitted April to October, most often in late August
• Shallow cultivation helps control
• Threshold for control in grass hay:4-5 larvae per square foot
• Smaller larvae are easier to control
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Black Grass Bug, genus Labops
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Black Grass Bug• Mostly a problem in grasses, sometimes
in grain
• Wheatgrasses among preferred hosts
• Overwinter as eggs in grass stems
• Nymphs hatch at snow melt/grass growth
• Development requires 4 to 5 weeks
• Adults mate, lay eggs, and die within about 4 weeks of maturation
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Black Grass Bug -Treatments• Early identification (April or May) and
treatment required (before egg-laying)
• Properly timed treatment can give control for years; slow-moving pest
• No actual threshold value found
• Damage measurement: 120 per square yard caused 18% losses in grasses
• Cultural: heavy grazing late fall/early spring, mowing & hay removal, burning
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Cereal Leaf Beetle Adult and Damage
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Cereal Leaf Beetle Egg
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Cereal Leaf Beetle Larva
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Cereal Leaf Beetle Larva and Damage
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Cereal Leaf Beetle• Commonly feeds on small grains, wild
oats, timothy, ryegrasses, & fescues
• Overwinters as an adult in plant debris or other hiding places
• Adults active in late April to early May
• Peak larval populations in mid-June
• Complete development in 4 to 6 weeks
• One generation per year
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Cereal Leaf Beetle Thresholds - Small Grains
• Three larvae or eggs per plant up to the boot stage
• One larva per flag leaf after the boot stage
• Pastures and forage grasses can tolerate a higher threshold than crops grown for grain
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Grasshoppers
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Grasshoppers
• Four species cause majority of damage
• Eggs laid in soil in summer & fall
• Overwinter as eggs, hatch in spring
• Development takes 4 to 6 weeks
• Most species have one generation per year
• Smaller nymphs are easier to control; nymphs cannot fly
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Grasshopper Thresholds - Small Grains
• >20 per square yard threshold in field margins, >10 per square yard in field interior => definitely treat
• 10-20 per square yard threshold in field margins, 5-10 per square yard in field interior => probably beneficial to treat
• barrier treatment (field margins) often sufficient for nymph control
• higher thresholds for pastures & forage
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Mormon Cricket, Anabrus simplex
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Mormon Crickets on Roadway
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Mormon Cricket• Prefers forbs but can feed on over 400
species of plants, including grasses
• Overwinters as eggs laid during summer in soil or in harvester ant mounds
• Eggs hatch in spring when soil temperature exceeds 40º F.
• Development requires 60 to 90 days
• One generation per year
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Insecticides for Pastures & Rangeland
• Limited number of insecticides labeled for these sites
• 15 active ingredients (of over 200 total insecticide a.i.’s registered in Utah)
• About 24 brands or product lines • About 48 Utah-registered products• Additional target pests included here:
ants and mosquitoes (larvae & adults)
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AZADIRACHTIN(Azatin)
• Type: botanical - derived from neem oil
• Action: feeding depressant & insect growth regulator; behavioral effects
• Sites: pastures & rangeland
• Pests: aphids, armyworms, cutworms, grasshoppers, Mormon cricket
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Bacillus sphaericus(Larvae Halt II, Vectolex)
• Type: biological agent - bacteria
• Action: mid-gut disrupter
• Sites: pastures & various aquatic sites
• Pests: mosquito larvae
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Bacillus thuringiensis var. kurstaki (Foray)
• Type: biological agent - bacteria
• Action: mid-gut disrupter
• Sites: pastures & rangeland
• Pests: armyworms & other caterpillars
• most effective against smaller larvae
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Beauveria bassiana(Naturalis)
• Type: biological agent - fungus
• Action: fungal hyphae penetrate the cuticle (exoskeleton of the insect)
• Sites: pastures only
• Pests: ants, armyworms, cutworms, grasshoppers
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Beauveria bassiana GHA(Botanigard)
• Type: biological agent - fungus
• Action: fungal hyphae penetrate the cuticle (exoskeleton of the insect)
• Sites: pastures & rangeland
• Pests: cereal leaf beetle, grasshoppers, Mormon crickets
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CARBARYL(Sevin)
• Type: carbamate
• Action: neurotoxin
• Sites: pastures & rangeland
• Pests: armyworm, black grass bug, cereal leaf beetle, cutworms, grasshoppers, Mormon cricket, western yellowstriped armyworm
• 14 days to grazing; bee hazard
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DIFLUBENZURON(Dimlin)
• Type: insect growth regulator - chitin synthesis inhibitor
• Action: inhibits formation of exoskeleton after molting
• Sites: pastures & rangeland
• Pests: armyworms, grasshoppers, Mormon cricket
• most effective on smaller nymphs
• Restricted-Use-Pesticide
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FENOXYCARB(Award, Logic)
• Type: insect growth regulator - juvenile hormone mimic
• Action: prevents molting into adult or pupal stage
• Sites: ant hills & rangeland
• Pests: fire ants, bigheaded ants
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HYDRAMETHYLNON(Amdro, Siege)
• Type: aminohydrazone
• Action: affects respiratory chain (utilization of oxygen by cells)
• Sites: pastures & rangeland grasses
• Pests: harvester ants, fire ants, bigheaded ant
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MALATHION(Fyfanon)
• Type: organophosphate
• Action: neurotoxin
• Sites: pastures & rangeland grasses
• Pests: armyworms, cereal leaf beetle, grasshoppers, Mormon cricket, mosquito adults, western yellowstriped armyworm
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METHOPRENE(Altosid, Pre-Strike *)
• Type: insect growth regulator - juvenile hormone mimic
• Action: prevents molting into adult or pupal stage
• Sites: pastures, rangeland, various aquatic sites; * irrigated pastures only plus aquatic sites
• Pests: mosquito larvae
![Page 36: Pastures & Rangeland: Insect Pests & Insecticides Alan H. Roe Insect Diagnostician Plant Pest Diagnostic Lab Utah State University.](https://reader033.fdocuments.net/reader033/viewer/2022042814/551a6687550346b52d8b4b04/html5/thumbnails/36.jpg)
NALED(Dibrom, Trumpet)
• Type: organophosphate
• Action: neurotoxin
• Sites: pastures only
• Pests: armyworms & other caterpillars, mosquito adults
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Nosema locustae(Nolo Bait)
• Type: biological agent - protozoan
• Action: mid-gut disrupter(?), replicates in digestive tract
• Sites: agricultural crops & rangeland grasses
• Pests: grasshoppers & Mormon cricket
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PYRETHRINS(Pyrenone, Pyrocide *, Pyronyl)
• Type: botanical - derived from pyrethrum flowers
• Action: neurotoxin
• Sites: pastures & rangeland grasses; * pasture grasses only
• Pests: armyworms, cereal leaf beetle, cutworms, grasshoppers, mosquito adults
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SPINOSAD(Conserve, Justice)
• Type: bacterial fermentation product
• Action: neurotoxin (similar to effect of nicotine)
• Sites: ant hills & rangeland
• Pests: fire ants