Insect Strip

Insect Strip

Friday, March 31, 2017

EPA Is not revoking Chlorpyrifos tolerances

In a news release March 29 by EPA the EPA Administrator Scott Pruitt signed an order that denies a petition to revoke any tolerances for the pesticide chlorpyrifos, which would have cancelled all chlorpyrifos registrations. EPA Administrator Pruitt said, “We need to provide regulatory certainty to the thousands of American farms that rely on chlorpyrifos, while still protecting human health and the environment. By reversing the previous Administration’s steps to ban one of the most widely used pesticides in the world, we are returning to using sound science in decision making - rather than predetermined results.” 
Sheryl Kunickis, director of the Office of Pest Management Policy at the U.S. Department of Agriculture (USDA) said “This is a welcome decision grounded in evidence and science. It means that this important pest management tool will remain available to growers, helping to ensure an abundant and affordable food supply for this nation and the world. This frees American farmers from significant trade disruptions that could have been caused by an unnecessary, unilateral revocation of chlorpyrifos tolerances in the United States. It is also great news for consumers, who will continue to have access to a full range of both domestic and imported fruits and vegetables. We thank our colleagues at EPA for their hard work.”
For over a decade EPA has placed numerous restrictions on pesticide products containing chlorpyrifos to address health and environmental risks from chlorpyrifos exposure. Some of the restrictions eliminated all homeowner uses, except for use in ant and roach baits in child-resistant packaging and uses for fire ant mounds and as a termiticide (June 2000). Limitations and restrictions were placed on such uses as for apples, grapes, citrus and tree nuts and discontinued uses on tomatoes. In 2012, EPA lowered pesticide application rates for some uses and created “no-spray” buffer zones around certain public spaces. All previous restrictions and limitations are probably still in place. 
This order means that EPA will not proceed at this time with any restriction for chlorpyrifos or changes to U.S. tolerances. “Instead, EPA announced that it will focus its attention on updating and revising its human health assessment for chlorpyrifos under the standard procedures of the Registration Review process scheduled for completion on October 1, 2022 in order to support future decision making,” said Phil Jost, Dow AgroSciences, U.S. Insecticides Marketing Leader.  
Link to Press release by EPA: https://tinyurl.com/n63439v

Link to EPA order: https://tinyurl.com/mxtuuxx  

Friday, March 10, 2017

Wheat Pests to be Watching For

With the warm weather wheat pests are starting to become active. So, now is the time to be scouting fields for those developing or damaging pest infestations. Since we have had a relatively mild dry winter wheat pest such as greenbugs, bird cherry-oat aphids, Russian wheat aphids, brown wheat mites, and wheat curl mites could be pests of concern. 

Greenbug and Bird cherry-oat aphid
The greenbug and bird cherry-oat aphid are most likely to be found together, but one of the aphids may be more abundant than the other aphid. The greenbug is light green and has a characteristic darker green stripe down its back. Greenbugs inject a toxin when feeding causing localized reddish spots on leaves, but under heavy infestations yellow and irregular shaped patches can spread across the field.

The bird cherry-oat aphid can be yellowish-green to a dark green or almost black in color. With the use of a hand lens there can be seen a reddish-orange area at the base of the abdomen around the cornicles. Feeding from the bird cherry-oat aphid does not cause any visible damage.

Greenbugs and Damage
Photo: Alton N. Sparks Jr., University of Georgia, Bugwood.org
 
Bird Cherry-Oat Aphid
Photo: Erin Hodgson, Iowa State University
Sampling Fields. Since lady beetles and parasitic wasps (shown below) are also active now and could help control aphids naturally, fields should be inspected and decisions to treat should be based on threshold levels. The “Glance ’n Go” sampling system (http://entoweb.okstate.edu/gbweb/index3.htm), as developed by Oklahoma State University and USDA-ARS, is a good tool for determining if greenbug or Russian wheat aphid infestations are at treatable levels. This sampling method takes into account the presence of parasitic wasp mummies when recommending treatment decisions. Our standard action threshold table for greenbugs can still be used for determining the need for a treatment, but it does not account for treatment costs and value of the crop. When using this action threshold take into account that when there are one to two lady beetles (adults and larvae) per foot of row, or 15 to 20 percent of the greenbugs have been parasitized, control measures should be delayed until you can determine whether the greenbug population is continuing to increase or declining. 


Lysiphlebus testaceipes
Photo: Jack Kelly Clark, University of California

Greenbugs and aphid mummies

Action Threshold Table for Greenbugs
Plant Height (inches)
Number of greenbugs per linear foot
3 - 6
100 - 300
4 - 8
200 - 400
6 - 16
300 - 800

Oklahoma State University along with South Dakota, Minnesota, and North Dakota have conducted studies that indicate bird cherry-oat aphids can cause from 5-9% yield loss from 20-40 aphids per tiller before wheat reaches the boot stage. The following procedure and table from Dr. Tom Royer, Oklahoma State University, can be used to calculate when bird cherry-oat aphid infestations should be treated:


Brown Wheat Mite
Our above normal temperatures and dry conditions are ideal for the heavy buildup of brown wheat mite. They actively feed on the wheat foliage on clear warm days, particularly during the mid-afternoon, and look like black specks moving on the leaves. At night they move down to the soil. A distinguishing trait for identifying these mites is the front legs which are about twice as long as their body. The life cycle from egg to adult is completed in just 10 to 14 days. All Brown wheat mite life stages are females (no males). They feed by piercing plant cells in the leaf that causes “stippling” leaf discoloration. Under heavy infestations plants become yellow, then dry out and die. When to treat for infestations is difficult because drought stress can severely reduce crop yields, making treats uneconomical. For most situations dryland wheat fields have more problems but with our dry conditions limited irrigated fields could be infested. In this situation an irrigation should reduce the mite population without a need for a miticide application. When the field becomes moisture stressed again mites may re-infest the field. Unfortunately a good economic threshold is not currently available for determining when to treat. A rule of thumb for treating in early spring is when there are several hundred mites per foot of row, or 25-50 mites per leaf. If we were able to get a hard driving rain this would control the mite infestations. 

Brown Wheat Mite
Photo: C. Patrick

Brown wheat mite damage to under irrigated wheat
Photo: C. Patrick

Pest Control
Insecticide products commonly used on the Texas High Plains for control of brown wheat mites is primarily dimethoate and, generally, chlorpyrifos for greenbug, Russian wheat aphid, and other aphids. Each will provide effective control but the pre-harvest interval may be important depending on harvesting for grain, grazing, and cutting for forage.

Product
Rate
PHI
Chlorpyrifos 4E(many different products)
1/2 to 1 pt/A Aphids (including greenbugs, bird cherry-oat aphid, Russian wheat aphids) and  Brown wheat mites
Do not apply within 14 days of harvest for forage and hay and within 28 days of harvest for grain and straw. Do not allow livestock to graze or feed on treated forage within 14 days of application.
Cobalt and Cobalt Advanced (chlorpyrifos plus gamma-cyhalothrin)
7-13 fl. oz./A (including greenbugs, bird cherry-oat aphid, Russian wheat aphids) and  Brown wheat mites
Do not apply within 14 days before harvest for forage and hay and within 30 days before harvest for grain and straw.Do not allow meat or dairy animals to graze or otherwise feed on treated forage within 7 days after last treatment.
Dimethoate 2.67
0.75 to 1.13 pts/A (Aphids-greenbugs)
0.75 to 1.5 pts/A (Brown wheat mites)
Harvest for grain - 35 days
Do not apply within 14 days of grazing
Dimethoate 4E and Dimethoate 400
1/2 to 3/4 pt/A (Aphids-greenbugs)
1/3 to 1/2 pt/A (Brown wheat mites)
Harvest for grain - 35 days
Do not apply within 14 days of grazing (some labels do not have this statement)
Proaxis (gamma-cyhalothrin)



Declare (gamma-cyhalothrin)
3.84 fl. oz./A (greenbug and mite spp.)
2.56 -3.84 fl. oz./A (bird cherry-oat aphid, Russian wheat aphid)

1.54 fl. oz./A (greenbug and mite spp.)
1.02 - 1.54 fl. oz./A bird cherry-oat aphid, Russian wheat aphid)
Do not apply within 30 days of harvest. Do not allow livestock to graze in treated areas or harvest treated wheat forage as feed for meat or dairy animals within 7 days after last treatment. Do not feed treated straw to meat or dairy animals within 30 days after the last treatment. Greenbug is known to have many biotypes. DECLARE  and PROAXIS may provide suppression only.
Karate with Zeon technology (lambda-cyhalothrin)



Warrior with Zeon technology (lambda-cyhalothrin)
1.92 fl. oz./A  (greenbug and mite app.)
1.28-1.92 fl. oz./A  (bird cherry-oat aphid, Russian wheat aphid)


3.84 fl. oz./A (greenbug and mite app.)
2.56 - 3.84 fl. oz/A (bird cherry-oat aphid, Russian wheat aphid)
Do not apply within 30 days of harvest. Do not allow livestock to graze in treated areas or harvest treated wheat forage as feed for meat or dairy animals within 7 days after last treatment. Do not feed treated straw to meat or dairy animals within 30 days after the last treatment. Greenbug is known to have many biotypes. KARATE with Zeon technology  and WARRIOR with Zeon technology  may provide suppression only.