Greetings Jonathan & apple crop folk,
This topic has provoked great discussion on the matrix of pest
management technology, much of which is taken for granted until
failure arises. Thanks to all of you who provided provoking insight
to a worthy discussion topic.
The original question of 'how other growers/subscribers to this list
determine rates of application for pesticides to fruit trees on your
farms' was woven into the fabric of discussion on insecticide failure.
As many have already said, the system of using TRV works if the
'right tools' are used, within the guidelines of label, pesticide
efficacy and the all elusive logic that experience can provide. The
caveat in my mind is 'right tools'. The right tools being those used
when TRV was developed (OP's, carbamates, pyrethroids from the
70-80's). My simplistic definition of right tools in 2010 would be
'efficacious tools' required by the magnitude of population pressure
and environmental conditions. Not necessarily those filtered through
marketing funnels.
Everything works when the populations are low. The men are separated
from the boys (read insecticide tools) when they are exposed to high
insect pest pressure and extremes in weathering that bear down on
them to tease out degrees of insecticidal efficacy. Those of us
conducting efficacy studies look forward to years such as 2009.
This year we experienced the highest apple maggot pressure I've
observed in my 20 years of working in tree fruit insect management.
We observed AM populations ranging from 5 to 180 flies per trap per
week observed throughout the commercial orchards of the Hudson
Valley. Populations were driven by moderate to high 2008 populations,
especially in hail damaged blocks that received light pest management
toward the end of the season. This was followed by favorable 08-09'
overwintering conditions. They were then amplified by ideal emergence
conditions of soil moisture from near constant rainfall and flies
maintained a strong presence from low residual levels.
In our research plots this year, the 'winners' for AM control were
Calypso (1.0% AM tunnelling damage to Red Delicious; 7.0 oz./A),
Imidan (2.8% damage; 5.33 lbs./A), followed by Delegate/Assail (9.3%
damage; 5.2/6.0 oz./A), followed by pyrethroids (>14% damage) and
untreated plots with 28% damage. Treatments in which Avaunt were
applied suffered 30% damage. Plot treatments applied to 4 varieties
at 108 GPA at 10 to 14d intervals were made depending on rainfall
from the onset of AM threshold to the end of the season.
From years of efficacy studies, three groups of insecticides rise
from the 'tool box' having active ingredients performing well against
AM year after year. Not all actives in these groups have the same
efficacy.
Organophosphates (Guthion, Imidan), 1960's chemistries, have always
been very efficacious against AM, having excellent weathering
residual properties.
Neo-nicotinoids, developed over the last 15 years, are very water
soluble. Two actives (Assail and Calypso) are very efficacious
against AM, but do not have as strong a weathering residual property
as the OP's. However, we have seen comparable results of these
products to the OP's (Imidan) regarding AM efficacy.
Pyrethroids (Asana, Baythroid, Danitol, Leverage, Warrior), 1980-90's
technology, are very efficacious against AM, but do not have strong
weathering residual properties or prolonged UV stability and require
closer intervals.
From our observations, it was nearly impossible to grow fruit using
organic or reduced risk pest control products this year unless you
were extremely diligent, sprayed at tight intervals as needed (<7d)
and spent lots of money on pest management materials. However, Non-OP
programs, such as neo-nicotinoid based programs provided excellent
commercial levels of insect control in heavy weather. It comes as no
surprise that products with 'low inherent efficacy levels' will fall
in years of heavy pressure and extreme weathering, no matter what TRV
you use.
Peter
--
Peter J. Jentsch
Extension Associate
Department of Entomology
Cornell University's Hudson Valley Lab
3357 Rt. 9W; PO box 727
Highland, NY 12528
email: [email protected]
Phone 845-691-7151
Mobile: 845-417-7465
http://www.nysaes.cornell.edu/hudson/faculty.php
http://www.nysaes.cornell.edu/ent/faculty/jentsch/
