Temperatures necessary to kill fungi in wood

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Material Information

Title:
Temperatures necessary to kill fungi in wood
Series Title:
Technical note ;
Physical Description:
3 p. : ; 21 cm.
Language:
English
Creator:
Forest Products Laboratory (U.S.)
Publisher:
U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory
Place of Publication:
Madison, Wis
Publication Date:

Subjects

Subjects / Keywords:
Wood-decaying fungi -- Control   ( lcsh )
Wood -- Heat treatment   ( lcsh )
Genre:
bibliography   ( marcgt )
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references.
Additional Physical Form:
Also available online.
General Note:
Caption title.
General Note:
"February 1956."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029720537
oclc - 61348044
Classification:
lcc - TA419 .U45 no.259
System ID:
AA00025004:00001

Full Text




TECHNO CA L NOTE NUMBER 259
UNITED STATES DEPARTMENT OF AGRICULTURE FOREST SERVICE
FOREST P S LABORATORY
MADISON 5. WISCONSIN C February 1956


TEMPERATURES NECtSRY TO KILL FUNGI I WOOD



Work at the Forest Products Laboratory has shown that fungi in wood are killed by heat most effectively when the moisture content of the wood is above the fiber saturation point. The data in table I were obtained for wood infected with Lenzites sepiaria, Lentinus lepideus, and Poria incrassata, 1 all prominent decay fungi. The moisture content of the wood was kept above the fiber saturation point while the heat was applied.


Table 1. --Recommended times at various temperatures to kill fungi in
wood*


Wood heated in : Wood heated in air
steam or equivalent :-----------------------------------------90 to 97 percent 35 to 40 percent
: relative humidity : relative humidity

Temperature: Time : Temperature : Time :Temperature : Time

OF. : Min. : F. : Min. : F. : M.

150 .- 60 : 150 :100:
160 :190
165 60
170 : 30 : 170 : 30 : 170 : 50
180 2 20 180 : Z0
z00 10
212 : 5 ::::


*The temperature is that of the wood, not that at the surface of the wood.





--Chidester, Mae S. Temperatures Necessary to Kill Fungi in Wood.
Proc. Amer. Wood-Preservers, Assn. 33:316-324. 1937.






In a later series of tests2 that involved 6 fungi and 5 wood species, a similar time-temperature relationship was found. The following is a listing of the fungi used and their source: Wood and locality from
Fungus* which obtained

Lentinus lepideus Fr. Jack pine (Pinus banksiana) Canada

Lenzites sepiaria (Wulf.) Fr. : Eastern hemlock (Tsuga canaden.sis) : Wisconsin

Poria incrassata (B. and C.) Burt.: Southern yellow pine, Virginia Fomes roseus Fr. : Jack pine (Pinus banksiana) Canada

Lenzites trabea (Pers.) Fr. : Western redcedar (Thuja plicata) : Wisconsin

Trametes serialis Fr. : Douglas-fir (Pseudotsuga menziesii)
: Oregon

*The first 3 fungi are the same strains as used in the first studies.



















2
Chidester, Mac S. Further Studies on Temperatures Necessary to Kill
Fungi in Wood. Proc. Amer. Wood-Preservers' Assn. 35: 319-324.
1 :39






Table Z presents the time-temperature relationships recommended on the basis of the second series of tests.


Table 2. --Recommended times at various temperatures to kill fungi in green wood


Wood heated in steam or an equivalent

Temperature* Time

SF. : Min.

150 : 75
170 : 30
180 : 20
200 : 10
212 : 5


*Internal temperatures, not temperatures at the
surface of the wood.


The recommended heating periods were based on the time after the wood had reached 150* F. These periods provide a margin of safety in that they are somewhat longer than the studies indicated were necessary for sterilization.

The recommendations in table 2 coincide with those in table I except that the heating period at 150* F. was increased from 60 to 75 minutes because of the longer time needed to kill Lenzites trabea. Work at the Forest Products Laboratory has shown- that these recommendations are easily met by ordinary commercial treatments of green wood when the preservative temperature is above 150* F.

It does not appear practical to sterilize wood at internal temperatures lower than 150' F. The most resistant fungi tested were not killed after 12 hours at 140*, 20 hours at 131*, or 24 hours at 122* F.



.-Mac Lean. J. D Comments on: Temperatures Necessary to Kill Fungi
in Wood. Proc. Amr. Wood Prestere crs' Assn. ~. 324 2. I >7


Z M r79t *




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