Actually (to the best of my knowledge),

PyrethrOIDS (such as those listed in the original email) are not OMRI  
approved. Some formulations of PyrethrINS (e.g. Pyganic) are. The  
differences being that the "oids" are artificially synthesized  
compounds while the "rins" are chrysanthemum extracts. Functionally  
the "oids" are quite a bit more active than the "ins", to a large  
extent because some formulations can provide 7+ days of residual  
activity whereas the "ins" residual activity can be as short as  
several HOURS. Please also note that any pyrethrin formulation  
including PBO (piperonyl butoxide; a synergist) also lack OMRI  
approval (e.g. Pyranyl).

So, unless the organic grower is spraying pyrethrins on a very regular  
basis (i.e. 4+ times per weekI doubt resistance from his/her local  
population would be much of a problem; of course immigrating resistant  
critters might be another story.

As far as Spinosyns go, Entrust has OMRI approval and is functionally  
about the same as Spintor (the conventional product).



On Jul 23, 2008, at 10:11 AM, Vicki Morrone wrote:

> Please note this concern for resistanct to two organically allowed  
> pesticides (pyrethroid as a natural botanical pesticide) is  
> restircted (allowed following NOP rule)and Spinosad (allowed).
> If you have expereince with this insect pest or these pesticides  
> please reply to the [log in to unmask] and to Tony Shelton  
> from Cornell University at [log in to unmask]
> Sincerely,
> Vicki Morrone
> From: Tony Shelton [mailto:[log in to unmask]]
> Sent: Tuesday, July 22, 2008 11:04 PM
> To: Great Lakes Vegetable WG
> Subject: Resistance in ECB
> Has anyone done tests to determine if European corn borer is  
> becoming resistant to pyrethroids and spinosad?  A local extension  
> educator in New York says that his sweet corn farmers are telling  
> him that they are experiencing resistance.  A few years ago we  
> published a paper that indicated a dramatic decrease in efficacy for  
> pyrethroids and spinosad against ECB with increased temperature  
> after some growers claimed 'resistance'.  So now we are wondering if  
> anyone has done some actual lab test for resistance.
> Musser, F. P and A. M. Shelton.  2005.  The influence of post- 
> treatment temperature on insecticides to Ostrinina nubilalis.  Pest  
> Management Sci. 61:508-510
> Abstract: The influence of post-treatment temperature on the  
> toxicities of two pyrethroids (lambdacyhalothrin
> and bifenthrin), a carbamate (methomyl) and a spinosyn (spinosad) to  
> Ostrinia nubilalis
> (H¨ubner) larvae was evaluated in laboratory assays. From 24 to 35 ? 
> C, the toxicities of the pyrethroids
> decreased 9.5- and 13.6-fold while spinosad toxicity decreased 3.8- 
> fold. The toxicity of methomyl did not
> change significantly. The results demonstrate that the most  
> effective insecticide against a pest may vary
> with environmental conditions. In situations where comparable  
> products frommultiple insecticide classes
> are available, temperature should be included as a factor in the  
> decision-making process.
> -- 
> ---
> Tony Shelton: [log in to unmask]
> Professor, Department of Entomology
> International Professor; Associate Director International Programs
> Cornell University/NYSAES, 630 W. North St., Geneva NY 14456
> PH 315 787-2352         FAX 315 787-2326
> If you would like to access a searchable archive of the all the  
> previous Mich-Organic listserv postings copy this URL and paste in  
> your browser address field

Matthew Grieshop PhD
Assistant Professor of Organic Pest Management
Michigan State University
205 Center for Integrated Plant Systems
East Lansing, MI 48824
Phone: (517) 432-8034
Fax: (517)353-5598
[log in to unmask]

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