Information Requests Monitoring System

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Request ID: 75
Request From: Steve Toth
Date Requested: Apr 13, 2004
Request: The following request was received from Wilfred Burr, USDA/OPMP. Please check with your contacts in your respective state/territory and send us your reply: Subject: Request for Feedback on Cabbage Thinning and Harvesting Activities Dear Colleagues: I am the USDA representative during Joint Regulatory Committee Meetings involving the Ag Reentry Task Force (ARTF) and the Agricultural Handler Exposure Task Force. During these meetings, the registrant members from each task force discuss the ongoing progress of worker exposure studies they are conducting with the three regulatory agencies: California Department of Pesticide Regulations, EPA Office of Pesticide Programs, and Health Canada PMRA. One ARTF study needing your expert input involves worker exposure as a result of cabbage thinning and harvesting. The preliminary results of this study are counter-intuitive. The preliminary transfer coefficient (TC) for thinning is higher than the TC for harvesting, indicating that there is more pick-up from foliar residues while thinning than from harvesting cabbage. Feedback from one expert is that weeding activities are conducted once or twice early in the season while the leaves are small and only done with a hoe - that there is no contact with cabbage leaves which may contain pesticide residues. During harvesting, there is considerably more contact with cabbage leaves by workers as they strip away the outermost leaves lying on the ground, cut off the cabbage heads at the soil level and toss them onto the truck. In the case of nappa cabbage, the heads are cut off, trimmed, washed and packed into crates while in the field. The three regulatory bodies, if they accept this study, would assign an identical transfer coefficient for thinning and harvesting. Your input/observations are desired since the cabbage study is one of three studies proposed by ARTF to be surrogate studies for all vegetable row crops. Is cabbage thinning conducted closer to the time of pesticide applications than harvesting such that there is more dislodgeable residue for the worker to contact? I am sending this to a number of you since cabbage is grown throughout the U.S. During the next ARTF meeting in June, we will be watching video clips of workers taken during the cabbage worker exposure study. I will also be prepared with your feedback Please forward this e-mail to others who might be able to comment. Thanks in advance for your assistance. A response by mid-May would be appreciated. Please do not hesitate to contact me if you have any questions or comments. Cordially, Teung ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Teung F. Chin, Ph.D. Biological Scientist Office of Pest Management Policy Agricultural Research Service United States Department of Agriculture Located at: APHIS 4700 River Road, Unit 149 (Room 5A66) Riverdale, MD 20737-1237 Phone (301) 734-8943 Fax (301) 734-5992

Responder: jonathan edelson
State: OK
Date Requested:
Response: Based on my experience with working on IPM in cabbage and having spent considerable time in commercial fields, the following message is correct in that the results noted are "counter intuitive". My suspicion is that as with many of the residue studies conducted in similar fashion, that the residues on vegetable crops in general are so small that the background residue noise, often called experimental error, is large in comparison to the actual residues they are trying to measure and that there may be no 'significant' differences in residue levels at all. Under actual field production conditions the workers may well be picking up residues from various sources other than the crop on which they are working, including their hand tools, farm implements, and/or vehicles in which they travel. Jonathan Edelson, Professor of Entomology Oklahoma State University

Responder: Robert Bellinger
State: SC
Date Requested:
Response: South Carolina Response 1
Thinning went out years ago. About the same time that precision planters came into wide use, thinning went. Also, hybrid seed is so expensive that thinning is now cost prohibitive.
The only 'thinning' that may take place may be plant bed pulling of transplants, unless processors up north use a lot of thinning. I have worked in Ga, Fl, NC, TN, and SC and no thinning takes place in those states.
Most fresh market cabbage is also field packed like napa. Here the cutters don't 'strip' away leaves in the field. They will bend the cabbage over and cut it where enough wrapper leaves are left on the head for the market and place it into a box in the field.
Slaw or bagged cabbage for the chopping market is normally larger than fresh market and has the wrapper leaves stripped away.
Also, I wonder where significant pesticide application takes place so early in the season that handling 2 - 4 leafed plants presents a risk. [comment deleted. RGB]
A reasonable pest management program would not present a risk even if thinning was a practice. In Florida at A. Duda & Sons, when we thinned cabbage, it was usually done with a hoe on plants that often just had the cotyledonary leaves. One seedling was left every 6 - 8 inches. Powell Smith (SC) [edits by R.G. Bellinger]
South Carolina Response 2
Read Powell's response [above] and it couldn't have been put any better.
[Comment deleted]
Richard Hassell [edits by R.G. Bellinger]
end South Carolina comments

Responder: Noel Troxclair
State: TX
Date Requested:
Response: Dear Dr. Chin, There are a couple of issues/questions in my mind that arise from the information found in your request for information regarding the higher transfer coefficient for cabbage thinning than for harvesting that was found in the ARTF study. The first thing I think needs to be done is to go back and check those data: check everything from start to finish, i.e., was everything properly documented, recorded, data entry done right, samples switched or misidentified, wrong decimal placement, certainty the analyses were done properly, etc., etc. Which residues are we talking about, insecticides, herbicides, or fungicides? I could come closer to understanding herbicide residues being found than the other classes of pesticides. If the residues were herbicidal, were the workers wearing footgear that would allow soil, thrown by the hoes during the thinning operation, to come into contact with the feet and ankles (I find it hard to imagine that there would be that much soil being thrown/moved)? In the Winter Garden of Texas, cabbage thinning is typically done close to a month or so after planting (meaning very small plants) and usually NO PESTICIDE has been applied after planting, or at latest, before cracking, until after thinning has occurred. Typically, the first pesticide application after planting occurs immediately AFTER the thinning operation has been completed. Under unusually heavy diamond back caterpillar pressure one or two applications of an insecticide may have been applied prior to thinning. HOWEVER, RE-ENTRY INTERVALS AND PROTECTIVE EQUIPMENT RESTRICTIONS ARE FOLLOWED IN THESE CASES. Additionally, at the time of year this occurs, the workers would be wearing long pants and boots because of temperatures. What this means is that, usually, the only pesticide used up to that time (thinning) was a herbicide that was applied about four weeks or so earlier. There generally should be no, to very little, pesticide residue on the foliage. Furthermore, thinning is done with a LONG-HANDLED HOE, so even if a pesticide had been applied after cabbage emergence, there should be absolutely no exposure from direct contact with foliage (assuming appropriate footwear). It also is rare for there to be many weeds in cabbage at this time unless the grower failed to use a herbicide at planting. In the Winter Garden, it would be highly unusual for human workers (other than hoe hands for thinning or for harvesting operations and crop consultants) to be on foot in a cabbage field. In my opinion, the study in question should not be considered at all because I think there is something wrong with the information. I personally judge it be untenable, given its questionable validity, that the study in question would even be considered for inclusion in the decision-making, especially given the breadth of its application and impact if it is included among the three for surrogate studies. Please feel free to contact me if you have any questions regarding my response. Thank you. Noel Troxclair

Responder: Tom Kuhar
Date Requested:
Response: If the residues in question are insecticides, then I would tend to think that exposure would be much greater during harvest than during thinning or weeding. Insecticide applications will increase as harvest approaches to assure the final product is insect free. Also leaf surface area and contact increases at harvest.

Responder: Allen Straw
Date Requested:
Response: All cabbage in Tennessee is transplanted. We have no direct seeding so we have no thinning. Obviously, there could be some "hand weeding" or hoeing when the plants are small. Most of this weeding is done with a hoe, therefore I would expect little direct contact with the cabbage plants. The most contact comes from harvest, which is just exactly as described in the e-mail below. Also, few if any crop protectant applications are made prior to early season weeding. Possibly a pre-transplant herbicide application and a post-transplant insecticide application. Many more have been made by the time of harvest. Therefore, I would expect the transfer coefficient to be significantly lower during weeding than during harvest. Best Regards, R. Allen Straw Assistant Professor Plant Sciences Commercial Vegetables and Strawberries UT Institute of Agriculture 2431 Joe Johnson Drive 252 Ellington Plant Sciences Knoxville, TN 37996-4561 Phone: (865) 974-7422 FAX: (865) 974-8850

Responder: Bill Jester
Date Requested:
Response: We do not thin cabbage in NC. Most fields, both spring and fall, are planted by transplants that eliminates both weeding and thinning. About 10 % of the fall cabbage is direct seeded with precision seeders. Herbicides and cultivation are adequate to completely eliminate the necessity for weeding. Weeding and thinning are a thing of the past in North Carolina. Most harvesting is performed by labor wearing rubber or cloth gloves. I see very little labor in the fields now that do not use some type of gloves. Bill Jester

Responder: Mark Mossler
State: FL
Date Requested:
Response: Here is the only response I have gotten so far on cabbage exposure. Will forward more if anyone else submits. Sincerely, Mark Mossler Pesticide Info. Office UF/IFAS Gainesville, FL 32611 352 392-4721 -----Original Message----- From: Gilreath, Phyllis R. [] Sent: Friday, April 09, 2004 11:47 AM To: 'Mark A. Mossler' Subject: RE: Cabbage pesticide residues Mark.....I really don't think we do a lot of thinning here in cabbage. We do have one producer who is growing tranplants in the field here for shipment to his production fields in New York. This is a new operation, first time he has tried this as an alternative to buying plants from Georgia, but I would think pulling plants for shipment would have similar concerns. Not sure if other production regions are doing this. I think you are probably correct in that early season pesticide applications are less than later on when cabbage starts heading. Bt and spinosad are used a lot especially early, with some other insecticides used later on in addition to Bt and spintor, including imidacloprid for aphids and occasionally stronger worm materials when needed. Actually I have one cabbage grower who also has released beneficials for certain pests and was able to go entire seasons sometimes on Bt alone. Don't remember what he was releasing but was working with someone from Texas. Hope this helps. Phyllis R. Gilreath

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