[Federal Register Volume 76, Number 12 (Wednesday, January 19, 2011)]
[Notices]
[Pages 3077-3079]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-984]
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DEPARTMENT OF AGRICULTURE
Animal and Plant Health Inspection Service
[Docket No. APHIS-2010-0059]
Notice of Decision To Revise a Heat Treatment Schedule for
Emerald Ash Borer
AGENCY: Animal and Plant Health Inspection Service, USDA.
ACTION: Notice.
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SUMMARY: We are advising the public of our decision to revise a heat
treatment schedule for the emerald ash borer in the Plant Protection
and Quarantine Treatment Manual and to retain the current treatment
schedule with a different treatment number. Based on the findings of a
treatment evaluation document, which we made available to the public
for review and comment through a previous notice, we believe that the
revised treatment schedule will be sufficient to treat emerald ash
borer.
DATES: Effective Date: January 19, 2011.
FOR FURTHER INFORMATION CONTACT: Dr. Inder P. S. Gadh, Senior Risk
Manager-Treatments, Regulations, Permits, and Manuals, PPQ, APHIS, 4700
River Road Unit 133, Riverdale, MD 20737-1236; (301) 734-8758.
SUPPLEMENTARY INFORMATION:
Background
The regulations in 7 CFR chapter III are intended, among other
things, to prevent the introduction or dissemination of plant pests and
noxious weeds into or within the United States. Under the regulations,
certain plants, fruits, vegetables, and other articles must be treated
before they may be moved into the United States or interstate. The
phytosanitary treatments regulations contained in part 305 of 7 CFR
chapter III (referred to below as the regulations) set out standards
for treatments required in parts 301, 318, and 319 of 7 CFR chapter III
for fruits, vegetables, and other articles.
In Sec. 305.2, paragraph (b) states that approved treatment
schedules are set out in the Plant Protection and Quarantine (PPQ)
Treatment Manual.\1\ Section 305.3 sets out a process for adding,
revising, or removing treatment schedules in the PPQ Treatment Manual.
In that section, paragraph (a) sets out the process for adding,
revising,
[[Page 3078]]
or removing treatment schedules when there is no immediate need to make
a change. The circumstances in which an immediate need exists are
described in Sec. 305.3(b)(1).
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\1\ The Treatment Manual is available on the Internet at http://www.aphis.usda.gov/import_export/plants/manuals/index.shtml or by
contacting the Animal and Plant Health Inspection Service, Plant
Protection and Quarantine, Manuals Unit, 92 Thomas Johnson Drive,
Suite 200, Frederick, MD 21702.
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In accordance with Sec. 305.3(a)(1), we published a notice \2\ in
the Federal Register on August 25, 2010 (75 FR 52305-52306, Docket No.
APHIS-2010-0059), in which we announced the availability of a treatment
evaluation document (TED). The TED recommended revising treatment
schedule T314-a, which provides a heat treatment schedule for ash logs,
including firewood, and all hardwood firewood that are moved from
emerald ash borer (EAB, Agrilus planipennis) quarantined areas. The TED
also recommended retaining the current T314-a as a general treatment
for various wood pests (rather than just EAB); we stated that we
planned to redesignate this treatment schedule as T314-c in the
Treatment Manual.
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\2\ To view the notice, the treatment evaluation document, and
the comments we received, go to http://www.regulations.gov/fdmspublic/component/main?main=DocketDetail&d=APHIS-2010-0059.
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We solicited comments on the notice for 60 days ending October 25,
2010. We received four comments by that date, from State governments.
The comments are discussed below.
The previous T314-a had indicated that ash logs, including
firewood, and all hardwood firewood must be heat treated at 71.1 [deg]C
(160 [deg]F) for 75 minutes in order to kill any EAB that may have
infested those products. The TED concluded that this treatment could be
changed to heat treatment of those products at 60 [deg]C (140 [deg]F)
for 60 minutes. The TED cited three publications in support of this
conclusion. The commenters addressed each of these publications.
Myers et al. (2009) \3\ evaluated a number of possible time-and-
temperature combinations for heat treatment of logs and firewood and
found that a minimum heat treatment of 60 [deg]C for 60 minutes was an
effective quarantine treatment of ash firewood against EAB.
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\3\ Myers, S. W., I. Fraser, and V. C. Mastro. 2009. Evaluation
of heat treatment schedules for emerald ash borer (Coleoptera:
Buprestidae). J. Econ. Entomol. 102: 2048-2055.
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One commenter stated that the experiment in Myers et al. (2009)
that most closely approximated the treatment described in the TED
(i.e., 60 [deg]C for 60 minutes) used a wet bulb depression method of
heating (moist heat), which greatly increased the rate of heating. This
commenter stated that, because the recommended revision to T314-a does
not include the rate or method of heating, it may or may not replicate
the treatments used in Myers et al. (2009). The commenter stated that
given the potential differences in heating methods, it is safer to go
with one of the higher temperatures evaluated in Myers et al. (2009),
65 [deg]C for 30 minutes, which also produced no EAB emergence.
The commenter is incorrect; while other experiments in Myers et al.
(2009) were evaluated with wet bulb depression, the experiment with
heat treatment at 60 [deg]C for 60 minutes was conducted in ambient
humidity.
Another commenter stated that, in experiment 2 in Myers et al.
(2009), because of the use of the wet bulb depression, the heating rate
of the wood was 30 percent faster than in any of the other experiments.
The heating rates in all of the Myers et al. (2009) experiments are
higher than what would be found in most commercial kilns, though there
are some exceptions. In any case, we have not found generally that
heating rates affect treatment efficacy; APHIS does not have any heat
treatments that specify heating rates. Rather, the key to effective
heat treatment is maintaining the treated articles at the stated
minimum temperature for the stated time.
One commenter stated that the firewood used in experiment 2 was not
handled in a similar fashion to that used in the other experiments. The
pieces used in this experiment were cut approximately 30 days prior to
testing, and stored at 4 [deg]C. The commenter stated that the authors
mention this inconsistency and state, `` * * * this would have resulted
in some additional drying of the firewood before the treatment.
Although the extra storage did not impact emergence from the control
groups, it may have increased the insects' susceptibility to the heat
treatments as the wood moisture content would have decreased over this
period.''
Holding firewood for 30 days prior to treatment is not unrealistic
for a commercial operation. In addition, the control group used in that
experiment clearly indicates the presence of viable EAB in the wood at
the time of treatment. Finally, the experiment involving treating the
firewood at 60 [deg]C for 60 minutes used firewood held for fewer than
10 days.
Myers et al. (2009) states: ``In experiment 3, adult emergence was
observed in firewood in 45, 50, and 55 [deg]C treatments for both 30-
and 60-min time intervals, whereas no emergence occurred in any of the
60 or 65 [deg]C treatments.'' One commenter expressed concern about the
analysis of the data that led to this conclusion. This commenter stated
that, in the treatment that is referred to as 60 [deg]C, that
temperature was in fact the ``target temperature'' in the experiment
(60 [deg]C for 60 minutes). The firewood in that experiment had a mean
treatment temperature of 62.2 [deg]C0.2 and a maximum
treatment temperature of 63.8 [deg]C0.4. The treatment with
a target temperature of 55 [deg]C for 60 minutes actually produced a
mean and maximum treatment temperature that was closer to 60.0 [deg]C.
In that experiment, the commenter noted, some EAB did survive.
The experiments in Myers et al. (2009) were conducted consistent
with how APHIS heat treatment schedules are administered. APHIS heat
treatment schedules do not indicate a mean temperature to be held
during the treatment period; rather, they specify a minimum temperature
that must be maintained throughout the treatment period. Thus, the
experiment in which firewood was held at 60 [deg]C for 60 minutes
corresponds to how treatment schedule T314-a will be administered.
One commenter stated that the results of the Myers et al. (2009)
experiments on EAB prepupae that were removed from logs and subjected
to various time-temperature combinations should not be considered
applicable to the discussion of a heat treatment standard for firewood,
except to note that the treatment time and temperature were sufficient
to kill EAB. Since these treatments occurred in petri dishes, the
commenter stated, the raw data from this experiment cannot be compared
to the raw data from the experiments that used real pieces of firewood.
We agree with this commenter. We interpreted the experiments on EAB
prepupae as providing useful information corroborating the results of
the other experiments in Myers et al. (2009).
The TED cited two other publications, by McCullough et al. (2007)
\4\ and Nzokou et al. (2008),\5\ as consistent with the results of
Myers et al. (2009). One commenter noted that McCullough et al. (2007)
states: ``No A. planipennis survived when chips were exposed to 60
[deg]C for >= 2 h in either of our studies, but 50% of the prepupae did
survive 1 h of exposure to 60 [deg]C.'' The commenter
[[Page 3079]]
stated that this statement would not support the recommendation to
change T314-a.
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\4\ McCullough, D.G., T.M. Poland, D. Cappaert, E. L. Clark, I.
Fraser, V. Mastro, S. Smith, and C. Pell. 2007. Effects of chipping,
grinding and heat on survival of emerald ash borer (Agrilus
planipennis Fairmaire) (Coleoptera: Buprestidae) in chips. J. Econ.
Entomol. 100: 1304-1315.
\5\ Nzokou, P., S. Tourtellot, and D. P. Kamden. 2008. Kiln and
microwave heat treatment of logs infested by the emerald ash borer
(Agrilus planipennis (Fairmaire) C Coleoptera: Buprestidae). For.
Prod J. 58: 68-72.
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That specific statement in McCullough et al. (2007) appears to be
in error; the rest of the publication describes experiments in which
wood chips were held at 60 [deg]C for 20 minutes and 2 hours, with no
experiment involving treatment at 60 [deg]C for 60 minutes. As noted in
the TED, McCullough et al. (2007) reported that EAB prepupae were
killed at 60[deg]C for 120 minutes, but not when held at the same
temperature for 20 minutes.
Another commenter noted that McCullough et al. (2007) did not test
treatment at 60 [deg]C for 60 minutes and stated that the publication
thus did not provide any data to support the current 30-minute
treatment recommendation for firewood.
The treatment revision recommended in the TED was for treatment at
60 [deg]C for 60 minutes, not 30 minutes. The McCullough et al. (2007)
data is thus consistent with the TED's recommendation. We also note
that McCullough et al. (2007) does not evaluate the treatment schedule
described in the TED; McCullough et al. (2007) used small chips, which
are more prone to drying during treatment than a piece of firewood, and
monitored air temperature, not wood temperature, which would be lower.
The TED cited the McCullough et al. (2007) results as being consistent
with the recommended revision of T314-a, not as supporting it directly.
One commenter stated that Nzokou et al. (2008) did not test logs
treated at 60 [deg]C for 60 minutes. Another commenter noted that
Nzokou et al. (2008) concludes with the suggestion that ``kiln heat
treatment at a level of 65 [deg]C or greater could be an effective
sanitization process for EAB-infested logs and wood materials.'' These
commenters stated that Nzokou et al. (2008) does not support lowering
the current treatment requirement to 60 [deg]C for 60 minutes.
As with McCullough et al. (2007), the TED cited Nzokou et al.
(2008) as consistent with the recommended revision to T314-a, not as
supporting it. Nzokou et al. (2008) observed the emergence of emerald
ash borer from logs heated to 60[deg]C for 30 minutes, but there was no
emergence at 65[deg]C for 30 minutes.
While Nzokou et al. (2008) conclude that 65 [deg]C is an effective
treatment, the authors did not test treatment times longer than 30
minutes. For kiln heat treatments of firewood, we prefer to extend
treatment times rather than increase treatment temperature. A typical
firewood kiln will operate 12 to 36 hours (or longer) during a heat
treatment run, so it is not difficult to extend a treatment by 30
minutes. In addition, many of the existing kilns in the United States
use hot water to produce heat. That design limits the internal
temperature of the kiln to approximately 70 [deg]C and makes it
difficult to produce internal wood temperatures greater than 60 [deg]C.
Thus, requiring heat treatment at 65 [deg]C for 30 minutes treatment
would be as effective as the revised T314-a but may not be as practical
to administer.
One commenter stated that, in the commenter's experience with heat
treatment of firewood, the current heat treatment requirements require
a core temperature reading to be at least 160 [deg]F for 75 minutes on
the largest pieces of firewood being treated. In practice, of course,
actual air temperatures inside the heat treatment chamber can vary
greatly, along with the time required to heat the chamber and its
contents to this minimum standard. Both the time and temperature can be
greatly influenced by the way the chamber is heated, moisture content
of the wood when it is placed into the chamber, outside air
temperature, size of the largest firewood pieces, arrangement of the
firewood inside the chamber, and management of the air flow inside the
chamber. This variability is made up for by the current treatment, the
commenter stated, but could be detrimental if a borderline or unproven
schedule is implemented, such as the proposed schedule.
APHIS heat treatment schedules identify the time for which a
specific minimum temperature must be achieved; they do not set that
minimum temperature to take into account variability at a facility.
Rather, heat treatment facilities are certified in accordance with the
requirements in Sec. 305.8 of the regulations as capable of properly
administering treatments. The certification process allows us to
determine if and where any cold spots may exist. In addition, each
facility is required to record temperatures of the firewood during the
heat treatment process and maintain records of each run. We recertify
kilns annually to assure that heat treatment facilities continue to
comply with the compliance agreement under which treatments are
conducted. Thus, the concerns the commenter cites are addressed through
the treatment facility certification process. The previous T314-a heat
treatment schedule that the commenter refers to was not developed to
address variability but based on the scientific evidence available to
us at the time.
One commenter expressed concern that the proposed T314-a for
hardwood firewood moved from EAB quarantined areas is not sufficient to
address the risks presented by other quarantine pests that may be
present in those areas.
We recognized the commenter's concern in the TED, which recommended
retaining the current treatment schedule of treatment at 71.1 [deg]C
for 75 minutes for other quarantine pests in wood articles as described
in Sec. Sec. 319.40-5 and 319.40-6 of our regulations governing the
importation of logs, lumber, and other unmanufactured wood articles. If
other pests for which treatment at 71.1 [deg]C for 75 minutes is
required are present in an area, ash logs and hardwood firewood moved
interstate from that area will be required to be treated in accordance
with T314-c, which contains the schedule of heat treatment at 71.1
[deg]C for 75 minutes.
Three commenters raised operational concerns with regard to having
two treatments, T314-a and T314-c, for hardwood firewood moved
interstate.
APHIS policy is to revise treatments to make them less stringent
when scientific evidence supports doing so. Any operational issues that
may arise from revising T314-a and adding T314-c as described in the
TED are outside the scope of this action. We plan to work with State
and local cooperating agencies, as well as the firewood industry and
other private cooperating entities, to implement the new treatment
schedules and resolve any confusion that may result.
Therefore, in accordance with the regulations in Sec. 305.9(a)(2),
we are announcing our decision to revise treatment schedule T314-a as
described in the TED. We have also decided to retain the current T314-a
as a general treatment for various wood pests (rather than just EAB)
and to redesignate this treatment schedule as T314-c in the Treatment
Manual.
The new treatments will be listed in the PPQ Treatment Manual,
which is available at the Web address and mailing address in footnote 1
of this document.
Authority: 7 U.S.C. 7701-7772 and 7781-7786; 21 U.S.C. 136 and
136a; 7 CFR 2.22, 2.80, and 371.3.
Done in Washington, DC, this 12th day of January 2011.
Kevin Shea,
Acting Administrator, Animal and Plant Health Inspection Service.
[FR Doc. 2011-984 Filed 1-18-11; 8:45 am]
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