[Federal Register Volume 76, Number 12 (Wednesday, January 19, 2011)]
[Pages 3077-3079]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-984]



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.


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 

DATES: Effective Date: January 19, 2011.

Manager-Treatments, Regulations, Permits, and Manuals, PPQ, APHIS, 4700 
River Road Unit 133, Riverdale, MD 20737-1236; (301) 734-8758.



    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, 

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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).

    \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.

    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.

    \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.

    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.

    \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.

    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 
    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 
    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.

    \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.

    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 
    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 
    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]