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 of canopy based on height, width and depth, the average tree shape and the density of the average tree. The ideal carrier volume should be no lower than 500 litres per hectare (53.5 US Gallons per acre) because there are physical limitations to what an air blasted droplet can achieve in terms of coverage. In a 1997 survey, apple canopies in New Zealand ranged from 10,000 to 40,000 m3/ha (142,913 to 571,653 cubic feet per acre) and increased by 30% between bud break and harvest. Therefore our new method proposes calibrating the sprayer and determining the ideal carrier volume at the beginning of the season, and at minimum, once more around the 1.0 inch fruit stage. Rate Adjustment: Studies in the U.K. have shown that spraying at a single, label-recommended application rate across apple orchards at different growth stages results in more than six-fold variation in average deposits. It has been said that, at minimum, the increase of leaf area from early stages of growth to maturity implies a concomitant increase in carrier volume to maintain coverage. It follows that the concentration of active ingredient should be held approximately constant to achieve the threshold dose rate intended by the label. For example, consider a label that specifies an application rate of say, two pounds of product per 150 gallons of product per acre. The volume of liquid that can be retained on a surface is limited, so once wetted, the surplus drips down to the lower leaves and so on to the soil. Once run-off has begun, the amount of product deposited is proportional to concentration but independent of carrier volume, which means deposit does not exceed dose once run-off has begun. In fact, run-off has been shown to reduce coverage uniformity by concentrating products at the edges of leaves. Therefore, if it can be demonstrated that the volume of foliage in the orchard canopy only warrants 75 gallons per acre to achieve dilute coverage, then by maintaining the label concentration, only 1 pound of product should be required to achieve the threshold dose intended by the registrant. Using our method, rates are held approximately the same as label concentration, although there are instances where concentration increases slightly. We are planning to demonstrate this method in Ontario in the coming season and in other provinces in subsequent years. It is not intended for chemical thinners or for use with alternate row applications. We are still determining which products are not eligible for reduction, such as biopesticides or products that only suppress (not control) the pest. So, there’s obviously more to it than I could write here, but I’m really looking forward to hearing first impressions from the group. Regards, *Jason ** **Jason S.T. Deveau, MSc, PhD **Application Technology Specialist Horticulture Technology Unit Ministry of Agriculture, Food & Rural Affairs 1283 Blueline Rd. @ Hwy. #3 Simcoe, Ontario, N3Y 4N5 (P) 519.426.8934 · (F) 519.428.1142*** *jason.dev...@ontario.ca** Agriculture Development Branch Research and Programs<http://www.omafra.gov.on.ca/english/ag.html> * P Please consider the environment before printing this email. ------------------------------ *From:* jmcext...@gmail.com [mailto:jmcext...@gmail.com] *On Behalf Of *Jon Clements *Sent:* January 25, 2010 9:50 AM *To:* Deveau, Jason (OMAFRA) *Subject:* Re: How to Post Jason, I am not sure what is wrong -- everything appears to be in order? Send me the message you were trying to post so I can look at it. Note that sometimes it takes a bit of time for the message to go through. Jon On Mon, Jan 25, 2010 at 9:01 AM, Deveau, Jason (OMAFRA) < jason.dev...@ontario.ca> wrote: Dear Webmasters, I recently attempted to post to the virtual orchard, but I don’t see my message. I used the respond button at the bottom of a recent posting. I’ve subscribed, so I don’t think that’s the issue. How does one post? *Jason ** **Jason S.T. Deveau, MSc, PhD **Application Technology Specialist Horticulture Technology Unit Ministry of Agriculture, Food & Rural Affairs 1283 Blueline Rd. @ Hwy. #3 Simcoe, Ontario, N3Y 4N5 (P) 519.426.8934 · (F) 519.428.1142* *jason.dev...@ontario.ca** Agriculture Development Branch Research and Programs<http://www.omafra.gov.on.ca/english/ag.html> * P Please consider the environment before printing this email. -- JMCEXTMAN Jon Clements cleme...@umext.umass.edu aka 'Mr Liberty' aka 'Mr Honeycrisp' IM mrhoneycrisp 413.478.7219 -- JMCEXTMAN Jon Clements cleme...@umext.umass.edu aka 'Mr Liberty' aka 'Mr Honeycrisp' IM mrhoneycrisp 413.478.7219
