Dave
Alternate row spraying is attractive with today's equipment, labour and fuel
costs. Years ago I sprayed rows 26 ft apart and it worked, so every other 13
ft seemed logical.
Alternate row spraying has worked for me as long as I follow the rules I set
out. Don't spray in the wind. Use enough water to drift to the next row
(70-80 gpa is used). Drive slow enough to allow drift to the next row (3.5
mph or under). Don't do it on big trees especially when fully leafed out. I
have a chart in the spray cab to switch from alternate to every row on the
go if weather is not cooperating (switch gears, close nozzles)
I am comfortable using EBDCs as a protectant with redistribution potential.
I am comfortable with insecticides that don't necessarily require every leaf
to be painted. I am not comfortable using it with systemic products,
thinners, and miticides that require full coverage today.
That brings up the fact again that registrations are now based on the lowest
effective dose (at least here in Canada) and it gets us into trouble under
adverse conditions.
I still have the gut feel I am overspraying. Trees 8-10 ft tall 7 ft in
diameter getting the same amount per acre as trees 16-18 ft tall and 20 ft
wide. I have calculated the TRV of dwarf trees at 40% of the largest I once
had. 2 rows would be 80%. Surely I can realize some efficiency cost here
somewhere.
Harold Schooley
Schooley Orchards
-----Original Message-----
From: apple-crop@virtualorchard.net [mailto:apple-c...@virtualorchard.net]
On Behalf Of Dave Rosenberger
Sent: Thursday, January 21, 2010 9:22 AM
To: apple-crop@virtualorchard.net
Subject: RE: Apple-Crop: Pesticide Rates and Tree Row Volume
Hi, Harold --
No, you should not deduct the drive-space of the untraveled
row when spraying on an alternate row basis because that "unused" row
middle is still a functional and essential part of the orchard (i.e.,
you drive that space on the next spray). Your trees occupy the space
within the dripline plus half of the drive space on either side of
the tree. The fact that you don't use the drive space on each trip
does not negate the amount of space that your trees are utilizing. In
research orchards, some of the wide space between trees serves no
function except as a distance barrier between plots.
Incidentally, I did not mean to imply in my comments that I
favored alternate row spraying, even though I can understand why it
is widely used in high-density plantings. In orchards where scab
control is a concern (especially given the very high carry-over
inoculum that is present in some northeastern NY orchards right now),
I'm not certain that alternate row spraying will provide adequate
fungicide coverage for sprays applied at bloom and petal fall, even
in high-density orchards on narrow spacings. When the DMI fungicides
(Rally = myclobutanil, Rubigan = fenarimol) were working well,
missing a few leaves shadowed by the trunk on the non-sprayed row
middles was not very important because the DMI fungicides would shut
down those infections when they were hit with fungicide on the next
spray. With widespread resistance to DMIs, we no longer can be
certain of "eradicating" infections that get started due to
incomplete coverage. I don't have a practical solution since most
growers can't afford the time required to drive every row middle with
trees on 10-14 foot row-middle spacings.
So Dave
I am wondering if your thinking has merit in commercial orchards. I spray
>alternate rows with 13 foot row spacings. And I do very much like the idea
of driving half the miles. I calculate things on a per-acre basis because I
don't feel comfortable at 30 or 40 gpa spraying alternate rows. I depend on
drift to finish the coverage on my side of the second row over. Should I be
calculating the acreage minus the unused driveway? (Eliminate the unused
space here so to speak) Rather than spraying a 26 ft row I am in fact
spraying one 20 ft wide (subtracting a 6 ft alley down the middle I am not
driving). This would reduce my acreage to 77% of what it was. I would
still
use the full amount of water (I still want the drift) but calculate rates
at
23% less. Forget the question mark a couple of sentences back. It's not
fair
to ask you to condone rate cutting. Is the logic there?
Harold Schooley
Schooley Orchards Limited
Simcoe, Ontario, Canada
-----Original Message-----
From: apple-crop@virtualorchard.net [mailto:apple-c...@virtualorchard.net]
On Behalf Of Dave Rosenberger
Sent: Tuesday, January 19, 2010 9:54 PM
To: apple-crop@virtualorchard.net
Subject: Re: Apple-Crop: Pesticide Rates and Tree Row Volume
Hi, Rick --
Your method of testing insecticides and Duane Greene's
comments about testing PGRs with airblast sprayers both make good
sense. I know both of you are good scientists, so I don't mean to
imply the following issue applies to your calculations of spray
rates. However, it came to my attention recently that not all
university researchers use the same method for calculating rates in
airblast trials in research orchards even if one ignores TRV.
The problems arise because many research orchards have wider
spacings between tree rows than commercial orchards so as to minimize
inter-plot interference from spray drift. However, one variable that
is used to calibrate airblast sprayers is the spacing between rows.
For example, growers might space apple trees on M.9 rootstock at 12
ft between rows whereas a test orchard might have 24 ft between rows.
To spray one acre, the sprayer will need to travel twice as far in
the commercial orchard as in the test orchard if one uses
conventional calibration formulas. But if the applicator in the test
orchard drives immediately adjacent to the test trees to apply
fungicides (spraying from one side only into the test trees and then
coming around to spray the opposite sides), then (s)he will be
over-applying the product compared to a commercial orchard if the
test-orchard sprayer is calibrated for a 24-ft row spacing.
In my opinion, the correct calibration for research orchards
is as follows: the sprayer should be parked in the drive row in the
same position that will be used to spray the trees. One should
measure from the tree trunk to the center of the sprayer fan and then
double that number to determine the effective "spacing between tree
rows" for the test orchard, and that number should be used for
calibration rather than the real spacing in the orchard. Thus, in my
experimental orchard with 24 ft between rows, I may allow my M.9
trees to get a bit wider than in a commercial orchard, so the limbs
will extend outward 5 ft from the trunk. I need another 3 ft from the
edge of the branches to the center of the sprayer. That means that
my tree row spacing for calibration purposes will be (3 ft + 5 ft)*2
>sides of the tree, or 16 ft because that is the width of the tree
plot that I am actually spraying. The other 8-ft between trees in my
widely spaced orchard is wasted space that really is not relevant to
calculating rates/A.
The above approach for calculating rates/A should be
reasonably accurate if the fan speed is adjusted to minimize the
amount of spray that is blown completely through the tree and into
adjacent rows. If you wish to account for additional deposition by
blow-through, then it seems that sprays must be applied in
commercially spaced rows by running the sprayer down the center of
the rows, using triple-row plots, and then collecting data only from
the center row this is sprayed from both sides and also gets
>blow-through form the adjoining row on either side. Maintaining
plots of this size can be prohibitively expensive for most university
programs if one is testing non-registered compounds on a
crop-destruct basis.
As pointed out by others, there are a huge number of
variables that affect results achieved when using air blast sprayers
to spray fruit trees, so much of our discussion involves details that
may be relatively unimportant as single factors given the high degree
of variability that occurs from one farm to the next. Furthermore,
most of our research plot test results are useful primarily as
comparisons of one product to another, and therefore the "absolute"
dose/A may be less important than having all of the treatments in a
comparison applied in identical ways.
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
--
**************************************************************
>Dave Rosenberger
Professor of Plant Pathology Office: 845-691-7231
Cornell University's Hudson Valley Lab Fax: 845-691-2719
P.O. Box 727, Highland, NY 12528 Cell: 845-594-3060
http://www.nysaes.cornell.edu/pp/faculty/rosenberger/
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Apple-Crop is not moderated. Therefore, the statements do not represent
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--
**************************************************************
Dave Rosenberger
Professor of Plant Pathology Office: 845-691-7231
Cornell University's Hudson Valley Lab Fax: 845-691-2719
P.O. Box 727, Highland, NY 12528 Cell: 845-594-3060
http://www.nysaes.cornell.edu/pp/faculty/rosenberger/
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"official" opinions and the Virtual Orchard takes no responsibility for
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