Re: Apple-Crop: Pesticide Rates and Tree Row Volume
Hi all, I'm sitting in an airport about to leave for Quebec to talk about Crop-Adapted Spraying to a group of apple researchers. Now that I've figured out how to post properly, I wanted to speak to Jonathan's point that regulatory agencies should make clear labelled changes to reflect the reality of orchard applications. In Canada, I've spoken with Heath Canada's Pest Management Regulatory Agency (who control label language and product registration) and Croplife Canada (the registrants that create agrichemicals) about this very point. A few registrants from the states claimed that they have attempted to put concentrations on their label, but the regulatory agencies insisted on per-acre units of measurement. When I asked the PMRA why that was, they said they had so much infrastructure oriented towards those units that it was a huge undertaking to consider changing them. All of their models for toxicity, rick, contamination, etc. are based on ground-area units. Both groups acknowledge the disconnect between units and grower practices, but don't seem to know what to do about it. Researchers have made a few suggestions to close the gap, and Jonathan touched on a few. One is establishing a standardized tree for determining label rates. Everyone would know it's volume, density, stage of growth and the environmental conditions for each and every product. Two is to use airblast sprayers with standardized set-up; no more spray guns for testing. Three is to publish coverage and efficacy variability on the label. For example, it might state discrete droplets per square centimetre in key locations on the tree, with variability. And/or it might note how many trees achieved what level of protection out of the total sprayed. All three approaches equal transparency. They make test methods that establish label rates as close to standard grower methods as realistically possible and they give the grower the data to adjust their methods based on the standardized conditions - a basis for comparison. This would still leave growers making adjustments in an ad hoc manner, but they would be based on more solid ground. None of this, however, changes the current fact that if a growers applies a rate and/or volume that departs from label-recommended values, they assume responsibility for any consequences. Sadly, I'm not sure how that would change. My hope is to either encourage standardized testing, encourage system-wide change to accept new label units, or give growers a simple and flexible tool to interpret labels (Crop-adapted spraying). Looking forward to comments. Jason Deveau Application Technology Specialist OMAFRA -- Sent using BlackBerry - Original Message - From: apple-crop@virtualorchard.net apple-crop@virtualorchard.net To: apple-crop@virtualorchard.net apple-crop@virtualorchard.net Sent: Mon Jan 25 21:14:37 2010 Subject: Re: Apple-Crop: Pesticide Rates and Tree Row Volume Hello All, I have found the discussion that has arisen from my initial questions fascinating and the answers nowhere near as clear-cut as I had imagined. My original post included a plea to the pesticide manufacturers, EPA and what is left of our unfortunately underfunded extension experts to come up with a product labeling requirement that takes into consideration the complexities of applying pesticides to fruit trees. I would assume that CLARITY would be of utmost interest to the EPA, whether or not they actually care if the product works. ( Maybe important enough that they would back it up with dollars for research?) I don't buy the Don't confuse the poor farmer by making them do algebra. argument. I also have trouble accepting the argument that a small tree equals a big tree. There is a limit to how dense the fruit and foliage can be before fruit quality suffers from light deprivation. Small trees put tree and fruit closer to the sprayer and have a smaller row volume. Our big old trees might not have grown as good quality fruit in the center of the tree, but there was still a need to protect it from insects and disease and thus a need to fill that volume of space with a cloud of spray mist that deposited an effective dose of pesticide. The variation on the TRV calculation that Jason Deveau discusses in his post might be based on better assumptions than our current approach, but it still contains the caveat that reducing the rate is at the grower's risk. We need a methodology that everyone can agree on so that if you do it right, the manufacturer will stand behind the product instead of hiding behind the lawyerly language written in tiny print on the label. I understand, as Dave Rosenberger points out, that from the manufacturer's perspective they might be recommending the least amount of product possible to leave more room in there risk cup for other crops, but if the rate is so close to the line so there is no margin for error, this needs to be
RE: Apple-Crop: Fwd: How to Post
Thanks Jon. I wonder what went wrong? I don't want to bother you whenever I want to post. Just to confirm - Should I use the button that appears at the bottom of a posting to respond to the whole group? It looks as if that button only lets me respond to the person that made the post... not the group. J From: apple-crop@virtualorchard.net [mailto:apple-c...@virtualorchard.net] On Behalf Of Jon Clements Sent: January 25, 2010 9:56 AM To: Apple-Crop Subject: Apple-Crop: Fwd: How to Post I am forwarding this message from Jason to apple-crop. Jon -- Forwarded message -- From: Deveau, Jason (OMAFRA) jason.dev...@ontario.ca Date: Mon, Jan 25, 2010 at 9:51 AM Subject: RE: How to Post To: Jon Clements cleme...@umext.umass.edu This is my first time posting on Apple-Crop. Methods for optimizing orchard applications are of particular interest to me and I've learned a great deal from this collection of experiences and opinions. I've tried to keep this brief, but there's a lot to say on the subject. Ontario has been developing a new approach to optimizing orchard applications. The model draws from the best parts of existing Crop-Adapted Spraying methods published and practiced since the sixties. Crop-Adapted Spraying can be defined as a process for matching carrier volume and product dosage to a growing leaf area within a canopy, or to variation between canopies, combined with the correct calibration and orientation of the sprayer. The goal of our model is to remove variation in applications. If it saves water and product in the process, that's a nice side-effect. Carrier Volume: Tree row volume is only one form of Crop-Adapted Spraying and it's based on assumptions that need to be reconsidered. I agree with Dave Rosenberger that we have good reason for questioning the validity of any method proffered 30 years ago. Trees, planting parameters and chemistries have changed. It's a sad irony that orchard application equipment (read airblast sprayers) is the only variable that has remained roughly the same. TRV is based on the carrier volume of 400 US Gallons / acre, which was pointed out in this discussion to be the volume of growth-regulating spray that will provide ideal coverage of a standard orchard using an airblast sprayer.. Generally, TRV models compare the volume of today's high density canopies to that of a standard orchard and make a proportional reduction in the volume of spray required to achieve dilute coverage for all orchard agrichemicals. There are a lot of inherent problems with making this conversion. I've seen a standard orchard defined many ways, spanning from 29,410 to 39,906 cubic metres per hectare (420,300 to 570,310 cubic feet per acre).. The ideal volume of 400 US gallons / acre seems to be based largely on best practices of the day and has been handed down somewhat reflexively. Is it the correct starting point for determining the right carrier volume for today's plantings? Canopy Density and PACE+: As was noted in this discussion, planting parameters and crop morphology is considerably different today from the standard planting. Can carrier volumes really be pro-rated as a percentage based on canopy volume given changes in crop density? I suggest growers consider a new method of Crop-Adapted Spraying currently in practice in the UK. Dr. Peter Walklate and the Silsoe Institute's PACE+ scheme (Pesticide application rate adjustment to the crop environment) has made some impressive contributions. In my opinion, the most interesting find is that the density of an apple canopy accounts for about 80% of the variability in spray coverage when using a fixed rate across orchards. Most variants of the TRV formula do not account for density. http://www.pesticides.gov.uk/HDC.pdf http://www.cigrjournal.org/index.php/Ejounral/article/viewFile/1240/1097 Still, PACE+ makes no recommendation as to the ideal carrier volume required for an application. As many of you have pointed out, the purpose of the carrier is to convey the agrichemical product to the target and distribute it in the desired pattern. Generally, a high droplet density (i.e. the number of discrete droplets per unit target area) is conducive to an effective application. Therefore, given the importance of the carrier, it is surprising that a specific volume is seldom indicated on the label except in generalities such as maximum and minimum. Coverage Constant: The method we're developing does not pro-rate that classic 400 UG gallons / acre. Instead, it works from the bottom-up by recommending the ideal volume of carrier required to give dilute coverage to one cubic metre of full apple foliage from an axial airblast sprayer. After an extensive literature review, I've determined the rate to be 0.08 litres per cubic metre (0.0006 US gallons per (cubic foot). With this coverage constant in hand, the model then determines the volume
