Comments on EPA 2005 Grower Impact Assessment of Azinphos-methyl use on
Apples (DP 307589)

Arthur M. Agnello

Cornell University

Dept. of Entomology

NYS Agricultural Experiment Station

Geneva, NY  14456

Phone: 315-787-2341

Email:   HYPERLINK "mailto:ama4@cornell.edu"  ama4@cornell.edu 

Potential impacts of AZM removal on pest management practices in the
eastern apple production region, particularly in NY, differ somewhat
from those in the western states, owing primarily to differences in our
pest complex, orchard production practices, climate, and widespread
distribution of alternate hosts.  Further pest complex differences in NY
distinguish us from the situation in other eastern states, such as PA,
WV, NC, and even MI.

Pests controlled by AZM in the eastern US – The primary target pests
of AZM applications in NY are plum curculio and apple maggot, followed
by European apple sawfly; codling moth and oriental fruit moth are
generally of secondary importance, and are assumed to be controlled by
applications made against the former species (note that this different
from MI and mid-Atlantic states where internal Lepidoptera are a more
serious threat).  In general, AZM and phosmet are not effective against
leafroller species (obliquebanded leafroller being the primary
representative in NY), tarnished plant bug, and San Jose scale.

Use of pheromones (MD, mating disruption) in NY and other eastern
locations – Internal Lepidoptera species have been a serious problem
for a relatively shorter time in NY than in other eastern states, and in
all eastern states for less time than in the western production regions.
 Of these species, codling moth (CM) has only recently become primary in
importance in the east, and in NY it is still not the most serious of
the complex that also includes oriental fruit moth (OFM) and lesser
appleworm (LAW).  Growers experiencing control failures of these pests
using conventional OP-based programs have only recently started turning
to MD as a potential alternative or complementary treatment in the east,
and least so in NY.  Some orchards with chronically high CM and OFM
population pressure do now receive MD treatments on a regular basis in
this region, but the acreage represented by this tactic is still a very
small percentage in most states (1-2% in NY, and probably not much more
than 5% in PA or even MI); also, this is never a stand-alone treatment,
but rather is combined with selective insecticides, and is still in a
relatively early assessment phase by most growers, who are in the
process of determining the specific dispenser technology, application
timing, trap monitoring details, and target efficacy levels applicable
to their situations.  Most apple plantings with an internal lep problem
do not have only a single species present, and usually must direct their
management efforts against both CM and OFM (with the possible addition
of LAW in some cases), which requires the application of 2 separate MD
products, which often involve different application timings.  Costs of
such programs can average as much as $140 per acre for the materials;
labor for hand-applied dispensers would represent an additional expense.

Alternative insecticides for internal Lepidoptera control – In NY, as
in the other eastern states, orchards under conventional insect
management programs experiencing problems from internal lep species
would likely go through a series of increasingly aggressive insecticide
program modifications before MD was considered, including shorter spray
intervals, higher rates, more sprays and increased coverage using
conventional OP's, alternations with pyrethroids, followed by more
selective specialty materials such as B.t., indoxacarb, methoxyfenozide,
and neonicotinyls such as acetamiprid (and thiacloprid, once it is
registered in NY, as anticipated this spring).  Kaolin clay is not
generally used in most commercial NY orchards, primarily because of its
higher cost, frequent application requirements, and tendency to wash off
during summer rain events.  CM granulosis virus has only recently been
registered and is not widely used; however, it would not be expected to
represent a reasonable alternative because of its limited activity
against OFM.  Novaluron and clothianidin are not currently registered in
NY.

Assessment of Proposed Scenarios if AZM were no longer available

First Scenario – In contrast to situations proposed in the western and
other eastern states, the substitution of phosmet for AZM in summer
spray programs would be a reasonable outcome in NY, inasmuch as phosmet
is regarded as equivalent to AZM in efficacy against plum curculio and
apple maggot, the two primary OP targets.  Moreover, it is not
envisioned that 4 applications of phosmet would be needed to replace 3
of AZM, and no measurable yield loss due to increased fruit damage would
be anticipated.  This spray-for-spray substitution is actually beginning
to occur already in NY, as a result of increased AZM REI and use
restrictions as well as greater scrutiny for AZM fruit residues by some
buyers.  It is acknowledged that phosmet is more expensive than AZM on a
per-use basis; NY estimates for commercial formulations are
approximately $14/A for AZM, and $16.50/A for phosmet, based on the avg
rate use provided in Table 7; this would result in a 3-spray program of
phosmet being only about 1.2 times greater than using AZM.  These
assumptions pertain to orchards in which CM or OFM were not problem
pests.

Second Scenario – Inasmuch as novaluron is not currently registered in
NY, we would assume a comparable scenario using single applications of
some of the other specialty insecticides that have activity against
internal leps as well as other summer insect pests requiring treatment
in NY (plum curculio, obliquebanded leafroller, and apple maggot), such
as methoxyfenozide, indoxacarb, acetamiprid, and thiacloprid (when
registered).  Because treatments for these pests vary according to local
population pressure, it is difficult to generalize about the number of
sprays of each product that would be applied.  However, it is reasonable
to propose a representative post-bloom program that could consist of as
many as 4 total applications using various combinations of these
products.  Depending on rates used, such a program would cost a maximum
of between $123 and $141 per acre, which would be 2.9–3.3 times more
expensive than the AZM program.  No yield loss due to fruit damage would
be anticipated in this scenario, as most CM/OFM populations are still
susceptible to these products.

Third Scenario – The proposal of substituting pheromone MD for 2 of
the AZM sprays is not applicable in NY because these products would not
affect plum curculio or apple maggot populations.  A comparable scenario
involving MD for internal leps in the summer would translate into
application of two pheromone products for MD of OFM and CM, which would
cost approximately $140 per acre, plus 1–2 applications of the
neonicotinyl products noted above for apple maggot, which would add
$72–83 to the spray bill, for a total increase of $212–223 per acre,
which would be 5.0–5.3 times as expensive as a 3-spray AZM program
(but only 1.5–1.8 times more than the second scenario above).

A 4-year RAMP project was initiated in six eastern states during the
2002 growing season to evaluate the efficacy and economics of insect
pest management programs in commercial apple orchards without the use of
organophosphate, carbamate, or pyrethroid insecticides.  The study
involved 49 growers and 467 acres of apples in all the major production
regions of MI, NY, PA, WV, VA, and NC.  Results showed that lb a.i./acre
using reduced-risk (RR) pesticides and MD were 74–92% lower than
comparable blocks grown using conventional materials, with no difference
in fruit quality due to insect damage.  However, costs were 45–130%
higher than growers' standard programs.  These studies also showed that
there are many orchards in which internal Lepidoptera and other
arthropod pests can be adequately controlled by using only reduced-risk
insecticides without mating disruption, but even these programs are
still more expensive (1.5X) than conventional programs.  In addition,
monitoring of pests in blocks treated with reduced-risk insecticides may
be more laborious and costly because of the narrow spectrum of activity,
unique mode of action, and precise timing needed for proper use of these
products.  Even when growers can manage internal leps with mating
disruption in apple blocks, they cannot eliminate control sprays for
other key pests.  These high costs of current programs using these
tactics will likely retard or even prevent the widespread adoption of
these programs by growers in the eastern US.

