Information Requests Monitoring System

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Request ID: 125
Request From: Steve Toth
Date Requested: May 10, 2005
Request: Note the following question regarding the application rate of the plant growth regulator dimethipin on cotton. Please forward this to the individual(s)in your repective states/territories that can respond to this question. Send any responses to the Southern Region IPM Center Information Requests Monitoring System by Monday, May 23, 2005. Thanks. Steve Toth EPA has a question concerning the application rate on cotton for the chemical "Dimethipin". Dimethipin is a plant growth regulator registered for use as a preharvest cotton defoliant and herbicide, which may be applied using groundboom sprayers and fixed wing aircraft. Dimethipin inhibits the synthesis of plant proteins responsible for stomatal control. This loss of stomatal control causes leaves to rapidly lose water, stressing the plant and leading to the production of ethylene, which ultimately results in leaf abscission and defoliation of the cotton plant. If you know of someone who should respond to EPA's question, please pass it along to them. EPA's question is listed below. Philip Poli Phil, I'd like to know the frequency with which cotton growers use the maximum seasonal application rate (0.56lbs. a.i./A) for dimethipin. We are currently discussing risk mitigation options, including a possible rate reduction because the most common dimethipin use rate is 0.31lbs a.i./A. Thus, I'd like to know more about how significant it is to maintain the maximum application rate. Thank you, Amaris Johnson, Chemical Review Manager U.S. Environmental Protection Agency Office of Pesticide Programs/SRRD p:703-305-9542 f:703-308-7042 Mailcode: 7508C

Responses
Responder: Roger Haldenby
State: TX
Date Requested: May 10, 2005
Response: Here on the High Plains of Texas, Harvade is sometimes used by our growers for defoliation in a tank mix of Harvade, Crop Oil Concentrate and Sodium Chlorate. The Texas Cooperative Extension recommended rates per acre are: Harvade 8 ounces COC 1 pint Sodium Chlorate 77 ounces Harvade has 4.9 lbs a.i. (dimethipin) per gallon. Therefore 8 ounces equals 0.31 lbs a.i per acre. Changing the maximum application rate to 0.31 lbs a.i. per acre would not, in my opinion, adversely impact defoliation operations in PCG's 41-county area. However, it is my understanding that the product is more widely used on Pima cotton, and also in the South-Eastern parts of the U.S. cotton belt. Roger K. Haldenby Vice President - Operations Plains Cotton Growers, Inc. 4517 W. Loop 289 Lubbock,TX 79414 Phone: 806 792-4904 806 793-1330 Fax: 806 792-4906 Mobile: 806 777-4741 e-mail: haldenby@plainscotton.org or haldenby@door.net

Responder: Robert (Bob) Bellinger
State: SC
Date Requested: May 10, 2005
Response: Steve, Our cotton res. specialist stated the following: "Bob, Harvade [Harvade-5F] and Leafless are used as defoliants in cotton in SC. The most effective and common rate is an 8 oz/a application of product. Lower rates are less effective unless tank-mixed with other harvest- aid materials. Harvade is an effective defoiant for us..." Bob B.

Responder: Mark Mossler
State: FL
Date Requested: May 11, 2005
Response: In checking with the weed scientist with cotton responsibilities, the 0.31 lb ai/A rate is what UF recommends, and this is supported by our extension materials. Consequently, it is not important to maintain the maximum rate for dimethipin in our opinion.

Responder: Mark Mossler
State: PR
Date Requested: May 11, 2005
Not Important/Relevant to my state(s)
Response: Cotton is not cultivated widely in PR.

Responder: Darrell Hensley
State: TN
Date Requested: May 12, 2005
Response: One of our largest ag. chem. suppliers sales less than 100 gallons annually of one product "Harvade 5F" containing this material.

Responder: Darrell Hensley
State: TN
Date Requested: May 12, 2005
Response: Rarely do Tennessee producers use more than 8 ounces (0.031 lb ai/ac) of Harvade. It is my opinion that lowering the maximum rate to 0.031 lb ai/ac would have virtually no impact on Tennessee Cotton producers. Bob Robert M. Hayes Superintendent, West Tennessee Experiment Station 605 Airway Blvd., Jackson, TN 38301 Ph. 731-425-4769 Fax 731-425-4773 rhayes1@utk.edu

Responder: Darrell Hensley
State: TN
Date Requested: May 12, 2005
Response: Harvade is not used by many farmers in the state of Tennessee. Use has gone down steadily in the last 5 years with the introduction of newer and cheaper compounds that do the same thing. Lowering the use rate to 0.31 lb. ai/a would not hurt a thing since the normal use rate is 8 oz as Dr. Hayes mentioned. Chism Chism Craig, Ph.D Extension Cotton and Small Grains Specialist West TN Experiment Station 605 Airways Blvd Jackson, TN 38301 Office: 731-425-4707 Mobile: 731-267-6086 chism@utk.edu http://www.utcrops.com

Responder: Darrell Hensley
State: TN
Date Requested: May 13, 2005
Response: Darrel; Just ran into the office this am to read a week of emails before leaving to plant more bean plots. Thought I would email my response to you and let you forward it to the appropriate channels. Had my own answer, but I checked with some agbusiness outlet personnel to make sure of my comments. The Harvade material in Gibson County is rarely used at the 14 oz labelled rate. Almost all instances the 8-10 oz. rate is used along with some Def and or Folex. The material (Harvade) is slow acting and needs the help of Def/Folex and the high rate tends to stick leaves. Thanks -------------------------------------------------------------- Bob Williams, Extension Area Specialist UT Agriculture Extension Service (731)364-3164, cell 731-225-0660 jwilli31@utk.edu

Responder: SM Brown
State: GA
Date Requested: May 23, 2005
Response: Dimethipin (Harvade) is used primarily at the rate of 0.31 lb AI/A (typically 8 fluid oz of the product Harvade) as a harvest aid in cotton. It would rarely IF EVER be used at higher rates or multiple times. In most years it is used on only a limited percentage (estimated less than 20 percent) of the acres in Georgia. sm brown

Responder: Steve Toth
State: NC
Date Requested: May 23, 2005
Response: According to Keith Edmisten, Extension Specialist, Department of Crop Science, North Carolina State University, our recommended rate of dimethipin (Harvade) is 0.31 lbs. a.i./acre (0.5 pint of 5 lb./gallon formulation). It would be rare for a grower to use more than the 0.5 pint rate. Harvade is used on about 10 to 20 percent of the acreage in North Carolina.

Responder: Frank Carter
State: TN
Date Requested: May 23, 2005
Response: The 2003 NASS report shows less than 0.5% of the US acreage is treated with dimethiphin (Harvade). Harvest guides in Alabama and California (see attached) lists dimethiphin (Harvade) use recommended at 0.31 lbs active per acre. Only one application per season is recommended. Roger Haldenby provided similar use of dimethiphin for Texas. Therefore, I do not see a problem with lowering the use rate to 0.31 lbs---- if this measure is necessary to mitigate a risk. I get uncomfortable with the maximum label rate being equal to the recommended rate. In the event that we get a situation (for example, unusual weather or change in variety) where an increase in rate of dimethiphin is required to do the job, then producers can only use a higher rate under Section 18 or a change in label rate. Do we have an option to lower the max label rate from 5.6 lbs down to something like 4.0 lbs. ? Please let me know if additional information is needed. Regards, Frank L. Carter, Ph.D. Senior Scientist, Pest Management National Cotton Council 1918 N. Parkway Memphis, TN 38112 901-274-9030 (Phone/Voice Mail) 901-725-0510 (FAX) fcarter@cotton.org

Responder: Mark Matocha
State: TX
Date Requested: May 26, 2005
Response: Assessment of Dimethipin as a Harvest Aid in Texas Cotton Cotton is a perennial plant and must be terminated prior to harvest initiation. Harvest aid chemicals such as desiccants, defoliants and plant growth regulators are used to reduce the foliage and plant moisture that interfere with machine harvesting operations. Many factors influence the effectiveness of harvest aid chemicals. Those factors include plant maturity, environmental conditions, and product rate. The full-length text, Cotton Harvest Management (Supak and Snipes, 2001), reviews harvest aid chemicals and the related plant processes in detail. Dimethipin, which is marketed as Harvade, Lintplus and Leafless has been evaluated in numerous research and grower field trials across the major production regions in Texas, including the Rio Grande Valley (Brownsville), Coastal Bend (Corpus Christi), Upper Gulf Coast (Wharton), Central Texas (College Station to Dallas), Rolling Plains (Vernon) and High Plains (Lubbock). In Texas, Harvade , Lintplus and Leafless are most commonly used at the 0.31 lbs. ai /acre rate. Very little Harvade is used in Texas; however, Lintplus and Leafless are used. Revision of the dimethipin labels (Harvade, Lintplus and Leafless) to a lower maximum use rate (ie. 0.31 lbs. ai/acre) would not pose significant problems in Texas cotton production systems. Cothren, J. T., C. Owen, andR. B. Ames. 2001. Physioloy of cotton defoliation and desiccation. In Cotton Harvest Management: Use and Influence of Harvest Aids (Ed:Supak, J. R. and C. E. Snipes). The Cotton Foundation, Memphis, TN (ISBN 0-939890-00-1)
Attachment included in response [Download]

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