I've been following this disscussion and it seems to me there is an important element that is missing. Everyone is focusing on efficacy in terms of AI/acre because that is the biggest concern of producers. However, from the few EPA papers I've read, it seems to me, the EPA is more concerned with the environmental impact than with actual efficacy. In other words, they seem to look at half-lives, water soluabilty, absorption coefficient, etc. All of these considerations have their basis in rate/acre calculations and have nothing to do with TRV. I guess what I'm trying to say is that licensing seems to be more concerned with environmental impact. Actual rates at which the product is effective seems to be secondary.
I'll qualify the comment that I'm really not sure of the particulars of EPA licensing. Perhaps my assessment is wrong. In that case, I'd invite any corrections. Mark Angermayer Tubby Fruits Bucyrus KS ----- Original Message ----- From: Richard Weinzierl To: Apple-Crop Sent: Tuesday, January 19, 2010 9:45 AM Subject: Apple-Crop: Pesticide Rates and Tree Row Volume Hello all. A little context before the main idea about how new insecticides (and other pesticides) are tested in tree fruit crops ... This thread started with a report that Avaunt performed poorly for apple maggot control when used in a spray program that relied on tree-row volume calculations. As a few others have pointed out, this seems to have been a banner year for apple maggot in many areas, so pest pressure likely helped to exaggerate anything less than a very high percentage of control. In addition, the Midwest Fruit Workers (and I think others) rate Avaunt as only Fair for apple maggot control, and several other compounds are rated Excellent or Good. My point ... any weaknesses, even small ones, in the effectiveness of tree-row volume modifications were probably multiplied by pest pressure and a less-than-ideal insecticide for this pest. That said, perhaps something more important in the overall discussion of tree-row volume calculations seems to me to center on the nature of data that support labels and recommendations for newer insecticides. Over the last15 years when I have tested insecticides, the trees that I use are characteristic of modern orchards -- small and well pruned. I determine the amount of water required to give thorough coverage, and that's the spray volume I use (often 100 gallons or less per acre). I determine the portion of an acre represented by the trees in each treatment, and I apply the amount of insecticide on the label (or in the experimental protocol) -- on a per acre basis. I have no illusions that work done in Illinois (not exactly the king of fruit production) determines or dramatically alters national and international labels, but I think most other entomologists test products in a similar fashion -- and pretty much always on small, well pruned trees. One might argue that this means that the per-acre rates on labels for newer insecticides have already been adjusted for (based on) the reduced tree-row volume of small trees. This is entirely different from adjusting the amounts of Guthion or Imidan or other older compounds whose labels may have originated with data from larger trees in older production systems. Those amounts could logically be reduced with the transition to smaller trees over the last few decades, but labels for newer materials such as Avaunt, the neonicotinoids, Delegate, Rimon, Altacor, etc. already reflect the necessary amounts for effective control on today's smaller trees. I realize that there remains a lot of difference in tree sizes in modern production systems, and adjusting spray volume and pesticide rates over those different tree sizes makes sense. Still, as we consider all the expert comments offered on this site over the last several days, it might be wise to also take into account the research basis for the per-acre rates expressed on labels for newer products. Rick Weinzierl Richard Weinzierl, Professor and Extension Entomologist Department of Crop Sciences, University of Illinois S-334 Turner Hall, 1102 South Goodwin Avenue Urbana, IL 61801 weinz...@uiuc.edu, Ph. 217-244-2126 -------------------------------------------------------------------------- The 'Apple-Crop' LISTSERV is sponsored by the Virtual Orchard <http://www.virtualorchard.net> and managed by Win Cowgill and Jon Clements <webmas...@virtualorchard.net>. Apple-Crop is not moderated. Therefore, the statements do not represent "official" opinions and the Virtual Orchard takes no responsibility for the content.
