Oklahoma State University
Critical Insects and Critical Insects and Conservation Tillage in Conservation Tillage in
OklahomaOklahoma
Tom A. RoyerDepartment of Entomology
&Plant Pathology
Conservation Tillage 101, Enid, Conservation Tillage 101, Enid, OK. February 8, 2006OK. February 8, 2006
Oklahoma State University
Topics for Discussion
Critical Insects/Mites Effect of Conservation Tillage
Greenbugs and other aphids Army cutworm White grubs Wheat curl mite Hessian fly
Oklahoma State University
Topics for Discussion
General lifecycle Management Tools
Effects of tillage on pest Cultural Controls
Rotations Planting date Resistant varieties
Insecticides
Oklahoma State University
Topics for Discussion
Critical Insects/Mites Effect of Conservation Tillage
Greenbugs and other aphids reduced threat Army cutworm Hessian fly White grubs Wheat curl mite
Oklahoma State University
Greenbug Lifecycle
Winged adults move into field in fall
Females produce live young soon after becoming adults, produce 35 young in one week at optimal temperatures
Feeding damage visible, and can cause substantial yield loss.
Oklahoma State University
Greenbug Management Tools for Greenbug Management
Tillage conservation tillage will likely help reduce colonization and
survival of greenbug Crop rotation
Rotation to non-host crops does not directly affect greenbugs Planting Date
Has some influence on greenbug outbreaks, limits fall window of migration, however mild falls can “open” window.
Resistant varieties Greenbug resistance is available
Oklahoma State University
Greenbug Management Tools for Greenbug Management
Insecticides Seed treatment: effective on fall generations Foliar applications effective tool for active infestations Need to determine applications based upon wasp activity
Oklahoma State University
Topics for Discussion
Critical Insects/Mites Effect of Conservation Tillage
Greenbugs and other aphids reduce threat Army cutworm reduce threat Hessian fly White grubs Wheat curl mite
Oklahoma State University
Army Cutworm Lifecycle
Moths arrive in fall from mountain ranges, lay eggs in tilled, thin or newly established stands.
Feed throughout winter, can tolerate very cold temperatures
Become active in early spring, can cause severe damage
Oklahoma State University
Army Cutworm Management Tools for Army Cutworm Management
Tillage conservation tillage will likely help reduce colonization and
survival of army cutworm Crop rotation
Rotation to non-host crops does not directly affect army cutworm Planting Date
Won’t greatly influence army cutworm outbreaks Resistant varieties
Army cutworm resistance is not useful
Oklahoma State University
Army Cutworm Management
Tools for Army Cutworm Management Insecticides
Foliar applications effective tool for active infestations
Oklahoma State University
Topics for Discussion
Critical Insects/Mites Effect of Conservation Tillage
Greenbugs and other aphids reduce threat Army cutworm reduce threat White grubs increase threat Wheat curl mite Hessian fly
Oklahoma State University
White Grub Lifecycle
May/June beetles arrive in spring, lay eggs in weedy, untilled fields.
1,2, 3-year lifecycles. Grubs feed for one to two years, typically are more of a problem the second year when 3rd instar grubs
Oklahoma State University
White Grub Management Tools for White Grub Management
Tillage Conservation tillage will slightly increase colonization and re-
colonization of white grubs, especially if fields contain grassy, weedy fallow, and tree stand is nearby (creek bottom)
Crop rotation Rotation to non-host crops can reduce white grub infestations
Planting Date Delayed planting can help with white grub infestations
Resistant varieties No resistance is known
Oklahoma State University
White Grub Management
Tools for White Grub Management Insecticides
Foliar applications are NOT effective tool for active infestations
Oklahoma State University
Topics for Discussion
Critical Insects/Mites Effect of Conservation Tillage
Greenbugs and other aphids reduce threat Army cutworm reduce threat White grubs increase threat Wheat curl mite increase threat Hessian fly
Oklahoma State University
Wheat Curl Mite Lifecycle
Adult mites measure 1/100 inches, are white, cigar-shaped, with 4 legs. They can grow from egg to adult in 8 days at optimum temperatures (77O F)
Hosts: wheat, corn, oats, barley and foxtail millet (and jointed goatgrass)
Transmit wheat streak mosaic virus
Oklahoma State University
Wheat Curl Mite Management Tools for Wheat Curl Mite Management
Tillage Conservation tillage will likely increase risk of survival of wheat curl mite,
unless volunteer is destroyed at least two weeks before crop is planted Crop rotation
Rotation not a concern, but planting next to other host crops (corn) can serve as a green bridge if corn is late planted.
Planting Date Can influence wheat curl outbreaks; avoid early planting
Resistant varieties Look for resistant/tolerant varieties to wheat streak mosaic
Oklahoma State University
Wheat Curl Mite Management Tools for Wheat Curl Mite Management
Insecticides Foliar applications are not an effective tool for active
infestations
Oklahoma State University
Topics for Discussion
Critical Insects/Mites Effect of Conservation Tillage
Greenbugs and other aphids reduce threat Army cutworm reduce threat White grubs increase threat Wheat curl mite increase threat Hessian fly increase
threat
Oklahoma State University
Hessian Fly Lifecycle
Adult fly is brown, looks like a small mosquito 1/8 inches.
Adults typically live for about 3 days
Mated females can begin to lay eggs about 1 hour after mating and lay about 200 eggs
Larvae feed on stems under leaf sheath, cause stunting or lodging
Oklahoma State University
Hessian Fly Lifecycle
Over summering generation infests wheat in fall
One to 3 generations from fall to harvest (major one in March)
Emergence is often triggered by favorable temperatures (45 to 50 degrees, and after a rain event).
Wheat at harvest
Volunteer wheat
Early planted wheat (for grazing)
Wheat for grain
Oklahoma State University
Hessian Fly Management Tools for Hessian fly Management
Tillage conservation tillage will likely allow increased survival of Hessian
fly Crop rotation
Rotation to non-host crops can reduce populations Delayed planting
important tool for reducing H. fly infestations, especially in north Resistant varieties
Important, need to know predominant races of H. fly
Oklahoma State University
Hessian Fly Management
Removal of volunteer wheat deprives hatching adults from a food source to lay eggs
Plowing old straw to a depth of 4 to 6 inches is a very effective way of reducing over summering Hessian fly
Burning straw will reduce, but many pupae drop to soil surface at harvest, so burning is not nearly as effective
Oklahoma State University
Hessian Fly Management
Crop rotation Wheat is the preferred host for Hessian fly Use of other crops can reduce the over wintering source of
fly pupae Hessian fly can travel up to a mile from their hatching site
Oklahoma State University
Hessian Fly Management
Variety Resistance: There are at least 12
Hessian fly biotypes, based upon their susceptibility to identified genes.
A collection of Hessian fly taken from North central OK was screened.
These biotypes can “shift” easily, if a single source of resistance is deployed over a wide area
Biotype A: 41% Biotype B: 16% Biotype C: 22% Biotype D: 13% Biotype F: 4% Biotype I: 1% Biotype L: 2%
H13 resistance gene, present in Molly, was 100% resistant to the sample.
Oklahoma State University
Hessian Fly Management
Variety Resistance: There are some hard red
winter wheat varieties that have resistance, but the resistance is not put in wheat varieties as a priority.
Susceptible varieties: Custer Jagger Jagalene OK 101
Resistant (Moderate) Chisholm Ike 2137 2145
Oklahoma State University
Hessian Fly Management Tools for Hessian fly Management
Insecticides Seed treatment: effective on fall generations Foliar applications not tested, and variable in results
Oklahoma State University
Hessian Fly Management (Chemical Control Seed treatments:
They are effective on fall generations, but not on spring
Gaucho and Cruiser are effectifve
In the SE U.S., spring applications of Warrior, timed to catch adult emergence has had some limited success, but has not been tested in OK.
Kansas greenhouse data: Gaucho 480 @ 48 g/100 kg
seed (1.6 fl oz/cwt) provided 100% control
Cruiser @ 39 g/100 kg (1 fl oz/cwt) provided 92% control
Kansas field data: Gaucho 480 @48 g/100 kg
provided 100% control, no control of spring infestation
Cruiser @34 g/100 kg (0.9 fl oz/cwt) provided 100% control in fall, no control of spring infestation
NT = No till, T = conv. till C= corn, W=Wheat
Oklahoma State University
Hessian Fly ManagementData Collected from Wheat Fields in Kay County OK 2005
Tillage Crop Rotation
Plant
Date
Seed Treatment
Plants
Infested
Tillers
Infested
NT W/W Early No 61% 41%
NT W/W E Yes 0% 0%
NT W/W E No 89% 40%
T W/W E No 22% 5%
NT CloseClose to wheat stubble
C/W E No 94% 51%
NT Far½ mile from stubble
CW E No 33% 10%
NT C/W L No 0% 0%
Oklahoma State University
Critical Insects and Critical Insects and Conservation Tillage in Conservation Tillage in
OklahomaOklahoma
Tom A. RoyerDepartment of Entomology
&Plant Pathology
Conservation Tillage 101, Enid, Conservation Tillage 101, Enid, OK. February 8, 2006OK. February 8, 2006