LOG DEFECTS

IN

SOUTHERN HARDWOODS

Agriculture Handbook No. 4

UNITED STATES DEPARTMENT OF AGRICULTURE

Forest Service

UNITED STATES DEPARTMENT OF AGRICULTURE

AGRICULTURE HANDBOOK NO. 4 T^^^^ 1950

Log Defects in Southern

Hardwoods

By

C. R. LOCKARD, Forest Products Technologist

J. A. PUTNAM, Forester

and

R. D. CARPENTER, Forester

SOUTHERN FOREST EXPERIMENT STATION

FOREST SERVICE

UNITED STATES GOVERNMENT PRINTING OFFICE - - WASHINGTON, D. C, 1950

FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, WASHINGTON, D. C, PRICE 25 CENTS

CONTENTS

Page

Introduction \

Factors affecting quality 2

Nature of log defects 3

Relation of defects to use 3

Classes of log defects 5

Log surface abnormalities ' 6

Adventitious bud clusters 6

Bulge 6

Bumps 7

Burls 8

Butt scar 8

Butt swell 9

Canker 10

Conk 10

Flanges 10

Flutes 11

Fork 11

Large holes , 12

Medium holes 12

Small holes 14

Knots 14

Limbs 15

Overgrowths 16

Seams 21

Split 22

Surface rise 22

Wounds 23

Log end abnormalities and imperfections 24

Dote 24

Page

Log end abnormalities and imperfections—Con.

Double pith 24

Grease spots 25

Grub channels 25

Gum spots 26

Loose heart 26

Mineral streak (mineral stain) 26

Pin worm holes 27

Ring shake 27

Rot 28

Shot worm holes 28

Soak 28

Spider heart 29

Spot or flag worm holes 29

Wind shake 30

General appearances which warn that log defects should

be sought 30

Signs in standing timber 30

Signs on end of log 32

Classification and evaluation of log abnormalities 33

Classification 33

Evaluation ^3

Appendix 35

Basic specifications for standard hardwood lumber

grades 35

Indications of deterioration in dead timber or stored

logs ^ 35

Common and scientific names of species referred to

in the text , 2>6

Log Defects in Southern Hardwoods'

->^- -<^

INTRODUCTION

The appraisal of hardwood timber and grading of

hardwood logs has often been classed as a mysterious

art, with most of the deep secrets held by old-time

timbermen. Even they were not infallible, however,

for when moving from one locality to another, many

failed to judge timber quality accurately and, as a

result, suffered financial reverses. Consequently, the

idea developed that there are undistinguishable basic

differences in hardwood timber of the same species

found in different localities, and that without highly

localized experience, appraisal can be no more than a

guess. The truth is that although there are important

local differences, the factors determining quality are

subject to analysis and can be systematically described

and universally applied to both standing and felled

timber (logs).

There is great need for complete understanding of

all the factors affecting hardwood timber quality.

Many appraisal problems that low stumpage values

for timber of high general quality formerly made relatively unimportant are now becoming pressing and

unavoidable. The primary fact here is the recognized

general decrease in average level and increase in variability of hardwood timber quality. Perfect trees are

rare; cull trees are plentiful. Volume per acre is low

and the trees are small. Tree size is especially important because the factors that reduce quality operate

much more severely in small timber than in large timber. For example, the same number of overgrown

limb stubs are obviously less damaging when scattered

through logs averaging 3 or 4 per thousand board feet

^ The term "southern hardwoods" is used not because all

species discussed are confined to the South but because, with

few exceptions, they are found in greatest abundance or reach

their optimum development there. The information applies,

however, wherever the species are found.

than when contained in logs averaging from 6 to 10

per thousand board feet.

Loggers also need a basic understanding of hardwood quality. In log-making in high-priced timber

of variable quality, failure to allow for and handle intelligently the factors affecting quality will result in

material loss. One especially vital point is determination of the lower limits of merchantability. Today, in

hardwoods, it is no longer possible to base merchantability simply on size, straightness, superficial smoothness, and freedom from rot and shake. Merchantability is equally influenced by type, location, and concentration of log defects, including those which are so

inconspicuous as to be almost unnoticeable.

Moreover, in order to utilize high-value stumpage

most profitably, it is becoming more generally necessary to prepare it for several markets, instead of cutting for only a single use. This means that from a

given hardwood tract, logging operations may produce

veneer logs, standard sawmill logs, tie and timber logs,

logs for low-grade construction lumber, stave bolts,

fence posts, pulpwood, and fuel wood. An understanding of quality is essential for such multiple-use

logging operations.

One other important need for definition of hardwood quality derives from the strong movement toward scientific forest management. A forester, marking timber under a program designed not only to feed

the proper raw material to individual industries but

also to maintain and improve the forest growing stock,

must know very thoroughly the factors on which quality is judged.

This publication describes what are probably the

least well understood of the factors determining log

quality—the indicators of defect which appear on the

surfaces or ends of the logs.
FACTORS AFFECTING QUALITY

In order to isolate and examine the basic factors

which determine the quaUty of a log and hence of a

tree, it is necessary to set up a standard. A theoretical

standard would be a straight, cylindrical tree trunk

consisting entirely of absolutely perfect wood. Such

a phenomenon is never found in nature, if only because every tree tapers and has a pith center.

A more practical standard for quality comparison

is a log with the following specifications :

1. It is a butt log, round or only slightly oval in

cross section.

2. It is 16 feet long and about 24 inches or more in

diameter at the top end.

3. It is straight, but has a slight taper and a slight

butt flare.

4. The wood is straight-grained. There is no requirement as to other characteristics of the wood, i. e.,

whether heart or sap, uniform or variable in density

or color.

5. The log has a "heart center" in a central cylinder

whose diameter is not more than 40 percent of the log

diameter. This heart center contains limb stubs and

pith center only; it is free from rot, shake, stain, and

similar imperfections.

6. The wood between the heart center and the bark

has no imperfections such as knots, holes, bark pockets,

mineral stain, or rot.

Standard products of high value will be cut from

such a log. Any deviation from these specifications,

except for a moderate one in size, will reduce average

value of potential products. The deviations which

are most important, occur most frequently, and thus,

for all practical purposes, determine quality are ( 1 )

change in position of log in tree, (2) reduction in size

of log, (3) crookedness, and (4) imperfections in either

the heart center (except for knots and pith) or in the

outer rim of wood.

Position affects quality because the further up the

tree the log is, the larger the heart center, relatively,

and the coarser the limb stubs in it are apt to be.

Change in size, especially in diameter, is very important. A decrease in diameter will cause a rapid increase in the proportion of products containing the

coarse heart-center blemishes. If made into standard

factory lumber, the logs of the larger diameters will

yield wider and more valuable boards; and the wider

the boards, the greater the possibility of raising values

by primary ripping to eliminate or segregate blemishes.

Changes in length are not so important in the individual log, for highest-grade products permit pieces of all

lengths down to 8 feet. However, there are definite

limitations on the percentages of short lengths which

can be included in large shipments of a given grade,

and there is sometimes a premium on shipments containing all long lengths ( 14 feet and 16 feet).

For logs of a given position and size, crookedness is

an important cause of reduced product value. There

are two variations of this factor. One is "sweep," a

gradual curvature or deviation from a straight line

drawn from one end of the log to the other. The

other is a sharp deviation termed "crook." The immediate effect of either is to bring the low-grade center

nearer the surface when the log is sawed. A "crossgrain" effect also appears in the product. Furthermore, sweep and crook sometimes originate from a

broken fork or heavy limb and thus may be related to

abnormal interior defect. The effect of crookedness

on quality is complex, but in all kinds of logs it reduces

the value of the product by weakening the wood

through the cross-graining effect or by causing an

abnormal distribution of blemishes. Besides reducing

value, sweep and crook inevitably reduce the volume

of the product. They also increase production costs,

for crooked logs are hard to handle on rollways, are

difficult to fit into loads, and frequently reduce rate of

sawing.

Final common deviations take the form of imperfections in the outer rim of wood or the heart center.

Such imperfections are broadly called "defects." Of

all the factors affecting wood quality, they are unquestionably the most important. They fall into two main

categories : ( 1 ) Those which reduce the volume of

sound wood or lower its durability, and (2) those

which lower the strength or utility. The first category

comprises the so-called scalable defects (chiefly rot,

shake, and checks), which are deducted from the gross

scale of the log and are normally removed from the

product in manufacture. The second includes such

things as knots, stains, holes, and bark pockets, which

cannot be removed in primary manufacture. Defects

of the latter class control the quality of the portion

of the log looked to for clear, unblemished pieces of

wood and are basic quality determinants where

strength or durability or fine appearance is required.

"Defective timber" popularly connotes rotten or

overmature trees, even though they contain much

usable material. The amount of scalable defect, together with size limitation, is often the main criterion

Agriculture Handbook No. 4, U. S. Department of Agriculture
limiting merchantability of logs or trees. Actually,

timber from which cull material (scalable defect) can

be removed in manufacture is not necessarily defective : there may be no serious blemishes in the remaining usable wood. On the other hand, perfectly sound

trees may be so defective as to be worthless because

of scattered degraders which cannot be eliminated in

manufacture. Since a defect that reduces volume

(e. g., rot) is entirely different from a defect that reduces utility (e. g., knot), it is logical to call scalable

defects "cull," and to apply "defect" only to those imperfections that lower the quality of the product into

which sound wood in the tree or log will be converted.^

It is from this viewpoint that defects are discussed

herein.

Usage gives the term "defect" to abnormalities on

the log surface as well as to imperfections in the wood.

These outside features are really indicators of imperfections in the underlying wood, and, strictly speaking, should be termed defect indicators. A branch

stub, for example, is an indicator of a knot in the

product to be sawed from the log. However, because

of usage and because timber appraisals deal with logs

as such, this publication terms these surface features

"log defects," and distinguishes them from imperfections in the wood by calling the latter "product

defects."

^ This distinction is not always clear-cut ; Cull when affecting only small areas may be left in the product, where it

impairs strength or utility and thus becomes a defect.

NATURE OF LOG DEFECTS

Log defects, and product defects too, can be defined

and evaluated only in relation to use. Whether a

blemish in the wood is a product defect, and whether

an indicator of the blemish on the surface or end of a

log is a log defect, will be determined by the specifications for the product into which the log is to be manufactured.

For example, mineral streaks would ruin the utility

of oak lumber for making fine table tops and thus

would be considered defects. They would not, however, affect the strength of a piece to be used as a tie,

and for this use would not be regarded as defects. An

unsound knot, 2% inches in diameter in the middle of

a floor joist 2 inches by 8 inches by 16 feet would

render the piece useless and hence would be a serious

defect. The same knot, in an otherwise clear 16-foot

board from which it was desired to cut two 7-foot clear

pieces for bed rails, would be a defect only if it prevented the cutting of the required clear pieces. Its

degrading effect would be equaled by a sound 54-iiich

knot that would pass unnoticed in a floor joist. Actually, for the bed-rail use, the piece would be of the

highest recognized grade.

Relation of Defects to Use

Thus, in analyzing the operation of the various factors which determine the quality of a hardwood log,

the nature and expected use of the end products must

be given prime consideration. Each use has its own

technical requirements, which are reflected in varying

tolerances for type, number, and distribution of imLog Defects in Southern Hardwoods

perfections permitted in the wood. The sawmill trade

has found over the years, however, that logs can be

grouped by major use requirements into three general

classifications, namely, those suitable for standard factory lumber, for ties and timbers, and for miscellaneous

low-grade or local-use products. In this report, the

terms factory log, tie and timber log, and local-use log

refer to these basic log-use classes.

It may appear that the discussions in this publication are preoccupied with large sawed products, and

that inadequate attention has been given to such products as veneer, cooperage, dimension and handle stock,

or other specialties. The fact is that although these

items may assume considerable local importance, they

are only a minor part in the total picture of hardwood

utilization. Probably 90 percent of hardwood timber

is cut into the products for the three general uses

described. Furthermore, the specifications for specialty products are closely related to those for factory

lumber in that relatively short, clear pieces of practically perfect wood or veneer sheets with few defects

are desired. It is probable that local studies of specialty products will judge defect significance on about

the same bases as those on which factory logs are

judged.

Factory lumber use is based upon producing lumber

which is later to be reçut into smaller pieces, free or

relatively free from blemishes and imperfections

(fig. 1). The value (grade) of such lumber is determined by specifications of the grading rules of the National Hardwood Lumber Association. These specifications control the yield of such high-quality pieces
as can be cut from the original board of a given grade.

High-grade boards are those which will yield high percentages of good pieces, with individual ones relatively

large. Low grades are those which yield low percentages of such material, generally only in the smaller

sizes. The technical base for the grading is the so-called

clear-face cutting. This is defined as having one face

free from defects and the reverse side sound, which

means free from rot, heart center, shake, and wane.

Texture is not considered. The sound reverse face will

admit certain defects such as sound knots, sound bird

peck, stain, streak, or worm holes—imperfections which

do not impair the strength of the piece. Tabular

statements of basic specifications for factory lumber

are found in the appendix, page 35.

FIGURE 1.—Factory lumber log. This type of log is relatively straight and will permit much center defect, but

must have wood in outer rim relatively free from blemishes.

Blemishes present must be so spaced that certain minimum

amounts of defect-free rim wood can be obtained. Distribution, rather than size and character of log defects, is the

most important factor.

Tie and timber use is that in which the pieces are to

be used more or less intact for structural or weightbearing purposes (fig. 2). Specifications are contained in the National Hardwood Lumber Association's 1943 "Standard specifications for structural-stress

grades of hardwoods and cypress," in the tie specifications of the American Railway Engineering Association, and in the standard specifications of the American

Society for Testing Materials for structural wood joists

and planks, beams and stringers, and posts and timbers.

These specifications in general control strength. The

position and condition of heart in the piece is especially important. Knots and other defects which

would impair the strength are limited to sizes which

hold impairment within satisfactory limits. Although

FIGURE 2.—Tie and limber log. This type of log is essentially straight and internally sound, with no rot, splits, or

shake admitted. Defects can be numerous if they are scattered and relatively small. Products are judged on

strength.

factory lumber grades allow for progressively more defects from the high grades to the low grades, tie and

timber specifications are rigid throughout with regard

to the inclusion of weakening imperfections. This results in log requirements different from those for factory lumber use. For example, enough high-grade

boards can often be taken from the outside of a log

with rotten, shaky interior and large but widely spaced

individual log surface abnormalities so that average

quality of products is high. Such a log might be a

cull for tie or timber use.

Miscellaneous or local-use products include those

uses that are generally not covered by any standard

specifications (fig. 3). High strength, great durability, or fine appearance is usually not required. The

products are of low value and are mostly sold in local

or restricted markets for such purposes as secondary

farm buildings, crating, mine tics, industrial blocking,

and miscellaneous construction. Whereas the products for the first two classes are usually sold over a

wide area through a variety of marketing channels,

local-use materials are generally sold direct to the user

by the producing mill. Perhaps the highest-value

products in this class would be structural boards, as

defined in the rules of the National Hardwood Lumber Association.

This system of log classification represents a sort of

one-way street. That is, all logs are allocated to the

highest class to which they are naturally adapted, regardless of any suitability for the purposes of a lower

class. The lowest class as shown by average sale value

is local-use logs. None of the logs suitable for local

use is also suitable for tie and timber use. Neither

Agriculture Handbook No. 4, U. S. Department of Agriculture
can logs suitable for ties and timbers be economically

manufactured into factory lumber. On the other

hand, most higher-grade logs can be and often are

used for lower-grade purposes. It is common to observe logs best adapted to factory lumber being cut

into ties and, vice versa, to see mills producing standard lumber from logs best suited for timbers. At both

tie and lumber mills can be found logs unsuited for

cither type of production. The reasons for this are

quite complicated and not due entirely to lack of understanding on the part of operators. One important

FIGURE 3.—Local- or miscellaneous-use log. This type of

log, because of size, placement, and character of defects,

cull, or crookedness, will yield only small percentages of

defect-free rim wood or construction material. It will

yield a variety of low-quality items in which strength or

appearance is not important.

reason is that there arc no accepted specifications covering these three types of logs to guide operators in

allocating logs to the most appropriate use.

Classes of Log Defects

Log defects can be divided into two general classes :

those found on the surface of the log, and those found

on the ends. Beyond this, there can be no general

classification. One reason is that, although most of

the important blemishes in wood are associated with

abnormal features visible on the log surface, some abnormalities do not reflect imperfections in the wood.

Furthermore, even though a log abnormality is an indicator of wood blemish, whether or not the blemish is

a log defect depends upon the class of log in which it

is found, for its effect depends upon the specifications

of the products to be made from the log.

In factory lumber logs, the most important wood

blemishes are those in the outer rim of wood. Few,

if any, of the indicators of these blemishes can be disregarded. This is true regardless of the size of the

blemish. In tie logs, the reverse may be true. In one

tie log, size of defect may be the controlling factor; in

another, the important defects may be only those unsound ones in the heart center. In local-use logs, the

low-grade nature and unexacting waste tolerances of

the products make requirements unexacting. In these

logs the main consideration is that of excessive size of

abnormalities or excessive amounts of scalable defects

which arbitrarily disqualify the log for the class.

Within a given type of log, there are a number of

general circumstances under which abnormalities may

be disregarded as defects. Certain kinds which may

have been included in the logs through operational

error can be disregarded under certain conditions.^

Other abnormalities are often superficial. That is,

they extend into the log for a distance less than onefifth of the log diameter (2 inches on a 10-inch log)

and hence do not enter the milling frustum or the included timber deeply. In such cases, they can be disregarded.

Since the conditions which make an abnormality a

log defect in one case and not in another vary so much,

there can be no general classification covering all

abnormalities and all log types. Therefore, the following discussions of individual log abnormalities cover

not only the description of the abnormalities but also

their significance in relation to use-classes or other

variables. No^ mention is made of the degree of degradation caused by log and wood abnormaHties classed

as defects. Within a given class of log, some defects

are more damaging than others, but the effect may be

conditioned by such other factors as log diameter or

straightness. This subject is discussed later under the

heading "Classification and Evaluation of Log Abnormalities."

^ In judging logs in standing timber, the appraiser has a

certain latitude as far as inclusion of log defects is concerned.

He can assume that cutters will use reasonable judgment and

eliminate a cull section, bad crook, or fork. When the log has

been cut, however, it must be judged "as is." The authors

have followed this principle in their judgments on defects,

except in the case of features which are obviously included

through operational error and the actual elimination of which

is still practical. It may be argued that any defect which

can be removed from the log or product by relatively simple

operation, without chopping up the product unduly, could be

disregarded, provided a loss in scale were taken. Although

there is merit to this argument, the nature of log defects can

not be adequately discussed unless it is considered that, with a

few exceptions, they cannot actually be removed from the log.

Log Defects in Southern Hardwoods

869828°—50 2 - " '
LOG SURFACE ABNORMALITIES

Log surface abnormalities arc unquestionably the

more important oi the two classes of log defects.

There is a better chance of observing indicators of

wood blemishes on the surface than of seeing the

blemishes themselves on the log end, and distribution

and frequency of product defects can also be judged

best from the surface indicators. All of the following

discussions of surface indicators of log defects are complete and inclusive ; a covered blemish associated with

a log defect is not discussed again as an end defect.

Adventitious Bud Clusters

Definition.—Adventitious bud clusters (fig. 4) are

abnormal groups of buds found at points on the stem

unrelated to the crown. They originate in the camFiGURE 4.—Adventitious bud cluster.

bium layer of the tree bole and may be formed at any

time throughout the life of the tree.

Occurrence.—They are found most frequently on

all species of elms, oaks, and maples.

Significance.—Underlying the adventitious bud

clusters are very small knots or small bark pockets in

the wood. Sometimes the blemishes arising from a

particular cluster that is visible on the surface may

not extend very far into the wood. However, a succession of others of similar origin generally appears

farther in the log. Wood blemishes caused by adventitious buds stop clear cuttings and are log defects

in factory logs. However, the knots and bark pockets

that the bud clusters indicate do not constitute defects

in tie and timber logs. Adventitious bud clusters can

also be disregarded in local-use logs.

Bulge

Definition.—K bulge is a general enlargement of the

stem of a tree or log, in the nature of a "barreling"

effect, often without an obvious cause such as knot or

callus formation. It may be near a wound, rotten

knot, knothole, or other point of entry for rot. It

generally indicates a cull section with the extent of the

rot shown by the extreme limits of the deformation.

There arc two types of bulges, butt bulge and stem

bulge (figs. 5 and 6).

F-455585

FIGURE 5.—Butt bulge.

Agriculture Handbook No. 4, U. S. Department of Agriculture
I'lcvRE 6.—Stem bulge.

Butt bulge is nearly always acrompanicd by hollow

butt. Rot generally extends beyond the hollow, and

the upper tapcrcd-off limit of the bulge usually indicates the approximate upper limit of serious rot. Butt

bulge has no special relation to species, although it is

most frequently of conspicuous development in the

oaks. In species like swectgum, elms, and ashes, even

considerable butt rot may not cause a clearly defined

butt bulge. In these species, the bark over even a slight

bulge often becomes smoother and darker and scales

off faster than in a sound stem. This is especially true

in sweetgum.

Stem bulge is not as common as butt bulge, but it

may be found in any species.

Significance.—As indicated above, bulges arc evidences of internal cull and under good operating practice are not included in logs. If all or a portion of a

bulge is included in a log and the part involved can be

cut off, the bulge need not be considered a defect.

Butt bulges can generally be so treated. If a stem

bulge occurs in the niiddle of a log, where it cannot be

cut out, then the area involved must be considered as

a cull section and, therefore, in factory lumber logs a

defect. A stem bulge will disqualify a log otherwise

suited for ties or timbers. In local-use logs, the bulges

can be overlooked, provided the accompanying rot

does not exceed the cull limits set for the class. The

identification and evaluation of bulges is most important in dealing with standing timber. In logs, a

bulge, unless included in its entirety, may show as an

abnormal end taper and cull may be the controlling

factor.

Bumps

Definition.—A bump is a protuberance on the log

which is covered with wood and bark (fig. 7). It may

be abrupt or it may be a smooth undulation which

FIGURE 7.—Bump.

gradually tapers back in all directions to the normal

contour of the log. A minimum bump is arbitrarily

defined as a swell on the surface with a taper steeper

than 1 to 6 (i. e., it is a bump if the distance from the

center to the edge is less than six times the height

from the normal contour to the top). If it has a taper

flatter than 1 to 6, it is classed as a surface rise (p. 22).

Low bumps are those with a taper of 1 to 6 to 1 to 3 ;

high bumps have a taper sharper than 1 to 3.

Occurrence.—Bumps are likely to occur on any

species. Low bumps arc particularly noticeable in

hard and soft maple, túpelo, soft elm, birch, and the

ashes, magnolias, and white oaks. High bumps are

conspicuously frequent in cedar elm.

Log Defects in Southern Hardwoods
Sisinificance.—About ninc-trnths of all bumps indicate knots, sound or rotten, projecting limb stubs, a

cluster of adventitious buds, or an excessive folding

or ingrowing of the bark over a scar.

In factory logs, low bumps can be disregarded in

hard and soft maple, túpelo, soft elm, birch, and the

ashes, magnolias, and the better white oaks; but high

bumps in these species are defects. In other species

all bumps are defects, for even low ones cover blemishes which are usually in the outer rim of wood where

they will limit clear cuttings.

In tie and timber logs, the effect will depend upon

the size of the underlying blemish. If the diameter

of a high bump is less than one-third of the diameter

of the log at the point where the bump occurs, or if the

diameter of the feature underlying the bump is estimated to be less than one-fourth of the width of a face

of the largest included timber (judged from the small

end of the log), then the abnormality can be disregarded as a defect. If the underlying feature is larger,

it is a defect. In the case of a low bump, it is difficult to

estimate the size of the underlying blemish. However,

the blemish will generally be so large that a low bump

must be considered a log defect in ovcrcup, chestnut,

pin, scarlet, black oak, and the water oaks, and in

cedar elm. In other species, low bumps can be disregarded as defects in tie and timber logs.

In local-use logs, bumps of both kinds are log defects

if their diameter exceeds one-half the diameter of the

log at point of occurrence ; otherwise they can be disregarded.

Burls

Definition.—A burl is a sound, hard, woody protuberance on the bole, more or less rounded or horizontally ridged in form, with no protruding limbs,

twigs, stubs, or indications thereof (fig. 8). It is sometimes related to aborted adventitious buds.

Occurrence.—Burls are uncommon, but are most

often found on hard maple, cow oak, walnut, the

magnolias, and occasionally yellow-poplar and northern red oak.

Significance.—A true burl is a surface indication

that the grain in the wood is distorted into a wavy,

curly, or bird's-eye effect. Other similar apparently

sound abnormalities, popularly classed as burls, may

contain considerable amounts of bark, rot, and even

insect channels. In factory logs, the true burl, if it

can be identified, technically is not a defect. However, the difficulty of identifying true burls requires

that all features ordinarily considered as burls be

FIGURE 8.—Burl.

classed as defects in factory lumber logs. Since burls

would unquestionably weaken a tie or timber, they

must be considered defects in these logs. In local-use

logs, however, they can be disregarded unless their

diameter at the point of occurrence is over one-hall

the diameter of the log at that point.

Butt Scar

Definition.—A butt scar is a generally triangular or

wigwam-shaped opening at the base of the bole, from

a few inches to several feet high (fig. 9). It may showweathered or stained or doty sapwood, rotten heartwood, or may be the opening into a rotten hollow butt.

When associated with advanced stages of rot or hollow,

it may be accompanied by a butt bulge (p. 6). It is

caused by anything that "skins" the base of the tree.

Fire is the commonest cause; others are logging and

cattle. Pin- and shot-worm damage (pp. 27 and 28),

which arc log defects in factory logs, are closely associated with butt scars.

Occurrence.—Butt scars may be found on all species.

Significance.—Since butt scars generally are associated with severe rot, the log is usually started above

the butt swell. However, sometimes a butt scar of

recent origin with a limited amount of rotten or stained

8

Agriculture Handbook No. 4, U. S. Department of Agriculture
wood is left on the log. In factory logs, the area involved is a defect, even though cull deduction is made

for it. In tic and timber logs, a butt scar may be disregarded if it and the asociatcd rotten wood are superFicuRE 9.—Butt scar.

ficial and do not enter the included tie or timber. In

standing trees, butt scar and associated rot may be disregarded if the logs can be cut so as to meet the minimum requirements of the log class. Otherwise butt

scar is a defect. Butt scar is not a defect Í7i local-use

logs.

Butt Swell

Definition.—A butt swell is an enlargement of the

bottom end of the tree trunk, over and beyond the

normal stump flare generally found in all species (fig.

10). It is a normal development, apparently related

to wetness of site, but not to injuries. Trees with butt

swell arc sometimes called "churn-butted" or "bottlebutted."

In standing timber, butt swell may be confused with

butt bulge. Butt swell is related to site and confined

to species listed below. Butt bulge, which is due to

injury and internal rot, is found in other species, especially oak, and is distributed more widely. Sounding

the butt with an ax or carefully searching for wounds

or butt scars will aid in identification. In the log there

will be no question, for the wood in the butt swell will

be sound, whereas it is likely to be very rotten in a

butt bulge.

Occurrence.—Butt swell is found in túpelo, swamp

blackgum, red maple, and green ash. Within the

species, the degree of butt swell varies according to

depth, duration, and seasonal occurrence of water.

Significance.—Butt swell is not a reflection of and

is not related to recognized imperfections in the underlying wood. It does not reduce lumber grade, and

therefore is not a log defect in factory logs. However,

the wood in the swell is often soft enough to limit the

use to which the lumber can be put. For instance,

green ash lumber cut from swelled butts, although

graded by standard rules, is classed in the trade as

"cabinet ash," and docs not command the high price

obtainable for "firm or better" taken from further up

FIGURE 10.—Butt swell.

Log Defects in Southern Hardwoods
the same tree. For tie and timber and local-use logs,

swelled butts in the harder species arc likewise not a

factor. In túpelo, the swelled section may be so soft

as to be worthless for any purpose. Then the log is

started above the butt swell, which therefore can be

disregarded.

Canker

Definition.—A canker is a definite, relatively localized nccrotic lesion, primarily of bark and cambium

(fig. 11 ). It is sometimes associated with a conk and

FIGURE 11.—Canker.

usually is an entrance for decay. In advanced stages

it is evidence of serious heart rot, generally extending

downward.

Occurrence.—It is commonest on the red and water

oaks, hickories, and ashes.

Significance.—In good operating practice, a canker

normally is not included in the log. Should it be included, it is a definite defect in a factory log. It is a

defect which will disqualify a log otherwise suitable

for ties or timbers. An included canker can in itself

be disregarded in a local-use log.

Conk

Definition.—A conk is usually a fibrous but sometimes a fleshy excrescence of definite form and structure on the bole (fig. 12). It is the fruiting body of

a rot-producing fungus contained in the tree.

Occurrence.—Conks may occur on all species.

Significance.—A conk usually is accompanied by

rot close to or in excess of the amount allowed in a

merchantable log of any type. However, if the log

will qualify as a factory log, the conk, together with

the associated rotten area, becomes a defect. It will

limit cuttings outside of the heart center even though

cull deduction is made. In a log otherwise suitable

for ties or timbers, conk is a definite defect, for it is

evidence of rot in the log interior which will disqualify

the log. In a local-use log the conk can be disregarded

as a defect, provided the rot with which it is associated

does not exceed the cull limit for the log class.

FIGURE 12.—Conk.

Flan<ies

Definition.—Flanges are buttress- or wing-like forms

at the base of the tree ( fig. 13 ). They are exaggerated

projections or convolutions of the normal stump flare,

and usually extend up the bole beyond normal stump

height, sometimes for 4 or 5 feet from the ground.

They appear to be related to wetness and softness of

ground.

Occurrence.—Most common in elms, water oaks,

and soft maple.

Significance.—The wood in flanges is, by definition,

superficial and thus outside the milling frustum or

10 Agriculture Handbook No. 4, U. S. Department of Agriculture
FIGURE 13.—Flanges.

included timber. Furthermore flanges do not reflect

and are not related to blemishes or imperfections in

the underlying wood. Therefore, in all types of logs,

flanges are not log defects.

Flutes

Definition.—Flutes arc folds or convolutions of the

surface of the trunk running up and down and generally confined to the base (fig. 14), but occasionally

extending even up into the second log. They often

include ingrown bark. They appear to be of normal

origin, related to softness of site, much as flanges are;

in fact, they are often confused with flanges.

Occurrence.—They are found most commonly in

soft and cedar elm, soft maple, and occasionally in

water oaks, pecan, and magnolias. The most exaggerated flutes are found in cedar elm.

Sisinificance.—Flutes usually do not extend deeply

into the log at the small end. When they do not, they

may be disregarded in all classes of logs.

Flutes are defects when they extend into factory logs

for a depth exceeding one-fifth of the log diameter, or

into the included timber in tie and timber logs. They

may be disregarded in local-use logs.

FIGURE 14.—Flutes.

Fork

Definition.—A fork is a crotch between double tops

(fig. 15). It is sometimes included when logs are

bucked to arbitrary lengths.

Significance.—A hidden efl^ect of a fork is double

pith and, generally, a bark pocket. In the fork portion, grade outturn and volume yield are both lowered

FIGURE 15.—Fork.

Log Defects in Southern Hardwoods 11
significantly. Including a fork on a log is an operational error. In tie and timber logs, the section should

be culled back to a point behind the separation. In

factory logs, the seam and any enclosed bark should

be scaled out following the standard practice for deducting for interior defect; but if the portion scaled

out is so large that it precludes cuttings, then the fork

is a defect. In standing timber, however, a fork is not

a log defect so long as logs can be cut which fulfill the

minimum requirements for the log type. Forks can be

disregarded in local-use logs.

Large Holes

Definition.—Large holes are unoccluded openings

over one-half inch in diameter (fig. 16). Among their

FIGURE 16.—Large hole.

causes are rotten knots, birds excavating infected spots,

and logging operations.

Occurrence.—Large holes may be found in all

species.

Significance.—In factory logs, all large holes are defects. In tie and timber logs, they are defects if their

size is over one-third the diameter of the log at the

point of occurrence, or if, regardless of size, they extend more than 5 inches into the log. If they arc

smaller or shallower than this, they may be disregarded,

provided they are surrounded by sound wood. Otherwise, they are defects. In local-use logs, large holes

may be disregarded unless their size is over one-half the

diameter of the log at the point where the hole occurs.

Medium Holes

Definition.—Medium holes are unoccluded openings, three-sixteenths to one-half inch in diameter,

through the bark into the wood. They include emergence holes of grubs, tap and increment borer holes, and

openings made by sapsuckcrs and carpenter ants.

Origin of the holes can be determined with some

readiness. Grub holes are clean-cut and unstained,

except in black oak logs where the tunnels are stained

black; they are usually more than 1 inch deep, are

irregularly spaced, and ramify through the wood. Increment borer holes arc of the same general character

but do not ramify. Sapsucker holes are usually found

in rows or bands, although occasionally the entire log

may be freckled with them. The individual holes

usually extend only slightly, if at all, into the wood.

Ant holes are irregularly spaced, but arc not clear-cut.

They are generally accompanied by frass and often by

a dark-colored exudation. They may or may not be

superficial, depending upon whether the insects have

been working on the cambium through a crack in the

bark or in a borer channel.

Occurrence.—Medium holes are found on trees of

any species. Sapsucker work, which results in the

familiar bird peck, is most often found in the hickories,

elms, and swcetgum, but occasionally in the oaks and

majsles, and in birch. Insect work is most prevalent

in the oaks. Tap holes will be found only in sugar

maple butt logs.

Significance.—Medium holes can be disregarded

in tie and timber and local-use logs. In factory logs,

they are extremely important defects, but significance

may vary with origin, age, or concentration.

Grub holes (fig. 17), increment borer holes, and tap

holes are definitely defects in factory logs, for the hole

12 Agriculture Handbook No. 4, U. S. Department of Agriculture
1? V- ?flH|g'f - ".1

^-i* '

K ^B^^^^Fv • • , , m dHi

^HJ'

Ajj^^^^H " '!

^^^\'

Z^^^^^^HK* >>'., »

v>:^i(|^H^ i

'

•

t'i»fl^H

^1

1

'

*-.,^^i^H^^^K «^

. '^l^l^I^P" ^B-' . ; « £¿¿^ ^^1^^^Bá

^^H . .^Mll J

11

V;

i

' -*,«■■ <:f.mft-ximki:«ti '1

FIGURE 17.—Grub hole. iiorui; 18.—Light bird peck.

or channel in the lumber stops cuttings. Both increment borer and tap holes are generally accompanied

by severe stain. With tap holes, there often is enough

rot so that an entire section must be culled. In addition, tap holes so often have forgotten dangerous metal

spouts that butts are usually "jumped" when a metal

detector is not used at the mill.

Significance of sapsucker holes depends primarily

upon age and concentration. Fresh or light bird peck

(fig. 18) may be disregarded in all types of logs. (Test

for freshness is lack of associated similar holes which

are occluded by callus tissue; measure of lightness is

four pecks per square foot. ) There are two cautions

in connection with light and fresh bird peck. One is

that trees so damaged have generally been subject to

previous and often repeated attack, and will have

occluded holes (overgrowths, page 16). When such

a combination occurs, it is a defect in factory logs. A

second caution relates to the hickories, even light bird

peck often results in circular columns of purple stain

running for considerable distances up and down the

tree. This stain is not a defect on lumber but does

constitute a degrading influence on handle stock.

Heavy bird peck (fig. 19), on the other hand, is generally older and usually is accompanied by overgrowths. FIGURE 19.—Heavy bird peck.

Log Defects in Southern Hardwoods

869828=—51) ?,

13
The effects extend into the wood in the form of bark

flecks or callus pockets. Heavy bird peck is a defect

¿71 factory logs (fig. 20), but not in tie and timber and

local-use loss.

FIGURE 20.—End view of hickory log showing stain caused

by bird peck.

Ant holes, if fresh, may be disregarded in all three

classes of logs. Fresh holes show no frass, exudations,

or occlusions. Ant holes that arc not fresh arc defects

iti factory logs but not in tic and timber and local-use

logs.

Small Holes

Definition.—Small holes are unoccluded openings

less than three-sixteenths inch in diameter leading into

the wood (fig. 21). They arc generally associated

with rot or wounds and are confined to the immediate

vicinity thereof. They arc made by several genera of

ambrosia and other beetles.

Occurrence.—There appears to be no significant relation to species. Ambrosia beetles seem to prefer the

softer and sappier species such as swectgum, but are

also found in the harder species. Shot worms arc most

prevalent in red oaks, ashes, and swectgum and appear to favor heartwood.

Significance.—Small holes on the surface are generally accompanied by other features which may or

may not be log defects. In factory logs, the usual

effect of small holes is to extend the area of other defects, such as wounds. The area in which the insects

work is definitely a defect, however. Small holes may

be disregarded in tie and timber logs and in local-use

logs.

Knots

Definition.—Knots are cut or brokcn-off limbs or

sprout branches, green or dead, jjrotruding, flush, or

depressed, but with exposed sound or rotten wood ( figs.

22 and 23). If the exposed wood is sound, the knot

is a "sound" knot; if rotten, it is an "unsound" knot.

Occurrence.—Knots are common to all species, but

the frequency depends upon the habit of the tree.

Cottonwood, túpelo, yellow-])oplar, and the ashes and

basswoods, for example, usually are conspicuously free

from knots. Pin oak, scarlet oak, and (on poor sites)

black oak are conspicuously knotty.

Significance.—A knot on the surface of the log or

tree represents a knot in the underlying wood.

In factory lumber, the degrading effects arise from

the distribution, which determines the yield of clear

FIGURE 21.—Small holes.

14 Agriculture Handbook No. 4, U. S. Department of Agriculture
cuttings, rather than from size, character, and condition of the individual knots. Obviously, large knots

will limit cuttings more than small knots. But a knot

in lumber, no matter how small, will limit a cutting.

Thus, any knot is a defect in factory logs. Even surface knots, arising from adventitious or sprout limbs,

cannot be discounted. While a particular knot of this

origin may taper out at a shallow depth, it generally

indicates successive layers of such knots for an indefinite depth into the wood.

In tie and timber logs, the degrading effect of a knot

depends upon an entirely different set of circumstances.

If the knot is larger than one-fourth of the face of the

largest included timber (measured on the small end of

the log), or if it is very rotten, it is definitely a defect

because it will affect the strength of the piece. Guides

to the breaking point between the two conditions are

as follows : A sound knot is a defect in a tic and timber

log if the diameter of the knot collar at the point of

occurrence is greater than one-third the diameter of

the log at that point. Knots smaller than this can be

disregarded as defects if they do not occur in whorls

equaling the effect of the larger knot, and provided

they are sound. If they are in whorls, then the combined effect must be considered and a whorl of small

knots the sum of whose collars exceeds the limit for

the single large knot is a log defect. Unsound knots

are judged by the same rule as sound knots, so far as

size is concerned, but the rot cannot extend more than

FIGURE 22.—Sound knot.

3 inches into the included timber. In practice, this

means that an unsound knot of acceptable size is a

defect if the rot extends into the log for a distance

exceeding one-fifth of the log diameter.

hi local-use logs, the only limitation on knots is that

they do not extend clear across individual pieces of

lumber. A good rule is that a knot is a defect if the

collar diameter exceeds one-half the diameter of the

log at point of occurrence or if the aggregate diameter

of a whorl of smaller knots is of equal effect. Other

knots, even if unsound, may be disregarded.

Limbs

Definition.—A limb is a branch or .subdivision of the

stem or an outgrowth from the stem ( fig. 24). It may

be part of the original branching, starting at the pith

of the main stem, or it may have started later from

adventitious buds at varying distances from the pith.

Occurrence.—Limbiness varies with growth or development habit of each species. It also varies with

conditions of growth (such as spacing and site) and

age and size. Species generally most free from limbs

are cottonwood, túpelo, yellow-poplar, and the ashes

and basswoods. Oaks—particularly black oak on poor

sites, scarlet oak, pin oak, and the water oaks—are

very limby.

Significance.—Limbs, of course, will be reflected in

generally sound knots in the sawed product. These,

regardless of size, condition, and character, degrade

factory lumber; hence, limbs are log defects in factory

logs. In tie and timber logs and in local-use logs, the

same rules apply that relate to knots; namely, there is

a size limitation. If the limbs are above the size limitation or if smaller and arranged in whorls, they are

defects which may prevent a log otherwise qualified

from being put in one of these two classes. Otherwise, they may be disregarded.

Log Defects in Southern Hardwoods 15
FIGURE 24.—Limbs.

Overgrowths

Many log surface abnormalities are features which

constitute a break in the normal bark pattern of the

tree. Knots resulting from broken branches, mechanical wounds (as from ax blaze or logging), and discrete holes such as those made by sapsuckers or ants

on the outside or those made by the emergence of insects from the inside, are features of this nature. As

the tree develops, such features arc covered over by

callus tissue and finally engulfed in the wood. Over

larger items, as the years pass, the bark reforms and

the existence of the feature in the wood is shown by a

deformation of the general normal surface contour. A

bump ( p. 7 ) is an example of this.

Smaller items may be entirely "lost" when they are

deeply buried, as far as any external evidence is concerned. However, for many years, until they become

so deeply buried as to lose significance as product defects, most items leave on the surface of the tree or log

either a definite structure of callus, or an identifiable;

break in the normal bark pattern. Such features are

classed as overgrowths. They actually are phases of

other log abnormalities described elsewhere. However, because many of them are inconspicuous and

easily overlooked and because they are the least generally understood of all the hardwood log surface

abnormalities which may or may riot be defects, they

are considered together for emphasis.

A recently overgrown knot is an example of a very

conspicuous and easy-to-recognize feature in this class.

Less easily recognized arc evidences of old ant and grub

work. Such damage may be so hidden that the only

superficial indication of its presence is a general ap-

]3carance of the bark which to the trained eye signifies

a need for close search for individual overgrowths.

The importance of overgrowths in the evaluations of

hardwood factory lumber logs in particular cannot be

overemphasized. Appraisal on the basis of all other

log defects would, in most situations, be fallacious if

overgrowths were not consistently recognized and given

full weight as defect indicators (fig. 25).

These overgrown abnormalities may be grouped into

four relatively distinct classes, three based on origin,

and a fourth in which origin is uncertain.

Overgrowths Due to Knots and Bark Pockets

Definition.—The most obvious overgrowths are

those indicating overgrown or buried knots and coarse

bark pockets (fig. 26). Where single knots are involved, the overgrowth in the early stages of development takes the form of the underlying defect. The

knot is covered over with callus tissue or there is a circular excrescence of callus tissue around the knot, but

still a separation between this tissue and the normal

bark. The knot is gradually engulfed as time goes on,

but for many years definite swirls or lines form on the

bark, making a characteristic pattern or roughly concentric circles.

These patterns, which are so definite that there can

be no mistaking their cause, persist until the knot becomes so deeply buried that there are clear boards

between it and the first saw line. Then the characteristic signs gradually disappear, and the deeply buried

knot is evidenced by a bark distortion which may be

merely a faint break in the normal bark pattern.

When bark pockets or clusters of small knots (generally from sprout growth) are involved, a small rise

or slight bump may be formed during the early stages

of overgrowth. The bump or rise resembles that covering a large single knot. These small bumps sometimes run together to form a sort of rosette. The final

stages are similar to those of the single knot, except

that the bark overgrowth is apt to be wider and more

irregular.

16 Agriculture Handbook No. 4, U. S. Department of Agriculture
F-455564-75

FIGURE 25.—Overgrown features are of fundamental importance in judging the quality of hardwood timber. A and B,

Overgrowth in water oak caused by small knot just recently buried. C and D, Overgrowth in blackgum due to deeply

buried knot. E and /', Small adventitious limb on white elm leading to knots. C and H. Overgrown adventitious buds.

/ and J, Bird peck in forked-leaf white oak. K and L, Large ant-caused overgrowth in overcup oak.

Log Defects in Southern Hardwoods 17
F-455628-30

FIGURE 26.—Overgrowths caused by knots.

Occurrence.—There is no relation between such

overgrown knots and species except that some species

arc Hmbier than others. This class of defect is often

overlooked in well-stocked stands of rapidly developing, well-cleaned second growth. Recognizing overgrowths in such stands is particularly important because, although general appearance may be one of

clearness of bole, the underlying knot is just beneath

the slab.

Significance.—Each overgrown knot or bark pocket

indicates an imperfection in the underlying wood. In

factory logs, each overgrowth is a log defect. In tie

.' -SF^

and timber logs, the overgrowths can be disregarded

except when they are of abnormally large size, or, if

small, when whorled (p. 15). Overgrowths of this

class can be disregarded in local-use logs.

Overgrowths Due to Insect Attack

Definition.—Common and extremely important

bark distortions are the occluded holes caused by the

work of such insects as wood borers and ants (fig. 27).

Borer work results in a sharp pucker which consists of

a pitted core, generally not over ^4 inch in diameter,

surrounded by callus tissue and distorted bark over an

F-455634. 455635. 455576

18

FIGURE 27.—Overgrowths caused by ants.

Agriculture Handbook No. 4, U. S. Department of Agriculture
arca ^ to 2 inches in diameter. Ants cause a vertical

slit from % to 3 inches long with callus area on both

sides. The total maximum affected area is typically

about 2/2 inches wide and 4 inches long. The most

extreme development of this latter type often looks

like a small, healed blaze wound.

Extremely severe borer work may cause a round

"plaster" of callus tissue as much as 3 inches wide

(fig. 28). In late stages, projecting scales of normal

bark from surrounding areas may hide these distorWithin the other hickories, occurrence is likely to be

most important on poor, dry sites, whether lowland or

upland.

In the oaks, three groupings can be made. In the

first group are those usually practically free from this

type of overgrowth. They include cow, Delta post,

northern red, Shumard, swamp white, forked-leaf

white, and cherrybark oak. (Damage to cherrybark

oak is pretty well confined to ant work, which is occasionally serious in overmature trees or on poor sites.)

F-455631-33

FIGURE 28.—Overgrowths caused by grubs.

tions. These concealing bark scales, particularly in

mature trees, may contain holes J/^ to ^ inch in

diameter, or exhibit numerous transverse breaks,

cracks, or ridges which are indications that overgrowths are present (fig. 50, p. 32).

Occurrence.—This class of overgrowth is definitely

related to species and within species to site and past

vicissitudes. Although widespread over the entire

East, it is most prevalent in the South. Especially in

the valleys of the Mississippi and its major tributaries,

occurrence is related closely to sites. Occurrence is

affected not only by the sharp differences between the

alluvial and upland situations, but also by the widely

varying growth conditions in the lowlands.

The oaks and some of the hickories are the species

most susceptible to attack. Of the hickories, sweet

pecan is an exception and is almost entirely free.

In the second group are those generally infested—

laurel, obtusa, scarlet, overcup, turkey, chinquapin,

and chestnut oak. In local areas with extremely good

site or growing conditions, this second group may be

relatively free from insect-caused overgrowths. But

when found on poor upland and mountain sites or on

areas with a bad fire history, the last four species in

particular arc likely to be badly damaged.

The third group may be divided into two subgroups.

The first subgroup includes those oaks which are generally found both on better drained lowlands (principally terraces and second bottoms) and on upland

sites. They include forked-leaf white (when found on

these sites), black, southern red, post, and shingle oak.

Insect-caused overgrowths are most likely to be found

in timber from dry, poor sites, such as exposed high

slopes, ridge tops, and most Coastal Plain pine sites.

On normal good hardwood sites, insect damage is

Log Dejects in Southern Hardwoods 19
usually slight or absent in these species. White oak is

especially free.

Occurrence of these overgrowths in the second subgroup, the typical flood-plain species (Nuttall, burr,

willow, pin, and water oak), usually varies more widely

than in the upland species. Here the timber is likely

to be very bad when the trees are growing in hardpan

flats on terraces, in backwater areas where there is prolonged inundation and tight clay soils, and on dry

upland sites away from alluvial soils. Site variations

in general and soil variation in particular, together

with degree of freedom from fire injury, may drastically reduce or increase occurrence in these species.

These species arc likely to be relatively free from this

defect on good flood-plain sites, but only on such sites.

In this third group are many other hardwood species

in which insect-caused overgrowths may be found, particularly in trees on unfavorable sites. However, there

are not the definite relationships nor the plain indicators found in the oaks, except that green ash in poor,

deep swamp sites may show serious infestation over

wide areas. Insect-caused overgrowths are also likely

to be important in extra large, overmature, and decadent sycamore.

SÍ!ínifica?ice.—Grub- or borer-caused overgrowths

mean channels in the wood and generally bark pockets

at the point of emergence. The holes indicated by this

type of overgrowth are rarely under one-fourth inch

in diameter and are often associated with rot and stain.

A particularly bad feature, which makes it hard to

isolate the efi'cct of any one occlusion, is that the borer

channels may run in any direction or pitch into the log.

In factory lumber, each channel or hole in a board is a

defect and in factory logs, therefore, each overgrowth

is a defect. In tie and timber logs, however, unless

the holes are very numerous (in which case there are

usually accompanying defects of other nature, such

as loose heart, shake, and rot), the holes and channels

are not considered in grading the product. These

overgrowths can also be disregarded in local-use logs.

Ant-caused overgrowths, on the other hand, indicate bark pockets which degrade factory lumber. The

uncertain feature is the plane in which the imperfection Ues. Although the particular bark pocket indicated by the overgrowth may affect only one or two

boards (the result of cambium excavation), the presence of such abnormalities at all indicates the strong

probability of additional similar lumber defects in

different planes. Ant-caused overgrowths, therefore,

are log defects in factory logs and may be disregarded

in tie and timber logs and local-use logs. It should be

noted, however, that heavy ant work is commonly associated with cheek, shake, and dote. The combination

often makes the log worthless for any purpose, just as

in the case of grub damage.

Overgrowths Due to Sapsucker Work

Definition.—Overgrowths that come from the pecking of sapsuckers (not the usual woodpeckers) may

be recognized by the conspicuous, horizontal row or

belt pattern of occluded holes about one-fourth inch

in diameter (fig. 29). Occasionally the entire log is

freckled with such bird peck. Where the holes are

continuous, a horizontal crack often forms.

Occurrence.—Species most susceptible to damage by

sapsuckers are hickories, elms, swectgum, and yellowpoplar. The oaks, maples, and birches are occasionally damaged moderately.

Significance.—Overgrowths of this class indicate

imperfections in the wood consisting of small holes or

groups of holes filled with callus tissue. One attack

would cause only imperfections in one plane and would

thus affect only a few boards in factory logs. However, most trees exhibiting such features have been attacked repeatedly over a number of years. The various degrees of occlusion and occurrence of horizontal

cracks indicate how long ago the attacks occurred.

^-TTî^ "..

F-455599

FIGURE 29.—Overgrowths caused by sapsucker work.

20 Agriculture Handbook No. 4, U. S. Department of Agriculture
The variability of damage makes it difficult to predict

exactly the extent. However, except for very large

butt logs, it is safe to assume that material damage extends far into the tree and affects a large portion of

the volume. Thus these overgrowths must be considered as log defects in factory logs. Usually the

damage does not weaken large pieces of wood, and,

therefore, this type of overgrowth can be disregarded

in tie and timber logs and local-use logs.

Bark Distortions

Definition.—Bark distortions arc breaks or alterations in the normal pattern of the bark (fig. 30). They

exhibit no characteristic formation which will enable

the cause to be established definitely from bark apF-455637-38

FIGURE 30.—Bark distortions.

pearance alone. They are the result of the burying

of any of the log defects already discussed. They may

cover insect damage, wounds, bird peck, or, most

commonly, knots.

Occurrence.—The relationship (as a defect) to species is that of the original cause. A smooth-bark tree,

such as beech, carries the evidence of these deeply

buried defects on the bole much more clearly than

does a rough-bark tree like soft elm. Bark distortions

are quite prominent on young swectgum, yellow-poplar, cottonwood, and second-growth red and water

oaks.

Significance.—'Rdsk distortions reveal the presence

of deeply buried blemishes. It is important to direct

especial attention to them because they are difficult to

see in their later stages, and consequently they are

easily overlooked by untrained eyes. They can be disregarded as defects in tie and timber and local-use logs.

Special studies by the Forest Products Laboratory

show that they must be regarded as defects in small

factory logs under 15 inches in diameter. Larger logs

are another matter. In about half of the logs over 15

inches in diameter, the underlying defects were buried

so deep that much clear wood could be obtained between the defect and the first saw line. In the other

logs, the wood blemishes were in an immediately degrading position. The importance varied also with

species. It was greatest in beech, for example, and

least in hard maple. Altogether, the degrading effect

of bark distortions is so variable in large factory logs

that they can be disregarded.

Seams

Definition.—Seams are longitudinal radial separations of the fibers in log or tree, either open or overgrown with callus tissue (fig. 31). If the seam is

FIGURE 31.—Scam.

Log Defects in Southern Hardwoods 21
overgrown, bark is often encased. Scams arc generally

caused by wind, lightning, or frost. They are likely to

be found in trees with cross or spiral grain, or which

are buttressed or leaning, or have internal stresses from

other special causes.

Occurrence.—Seams may be found in any species,

but are common in the oaks, ashes, and maples, and in

birch and honey locust.

Significance.—The significance of seams depends

upon their depth. Often a scam is associated with rot,

and consideration must be given not only to the seam

but to the extent of the rot. In factory logs, if a seam

together with any associated rot extends into the log for

less than one-fifth of the log diameter, it can be disregarded as a defect. If it goes deeper, even though

an area is culled out to allow for loss of lumber, it is

still a defect in that it stops cuttings. In tie and timber

logs, it can be disregarded if it does not enter the largest included timber, as measured on the small end of

the log. If it is sound and enters the timber only

slightly, say one-half inch, it will probably be permitted in the piece and therefore can be disregarded.

However, if a sound or unsound seam enters the timber

deeply, it must be classed as a log defect which will

eliminate the log from or degrade it for this class of

use. In local-use logs, most seams can be disregarded.

Split

Definition.—A split is a longitudinal separation of

fibers extending deeply into the milling frustum of a

factory log or into the included tie or timber of a log

designated for this use (fig. 32). A split is generally

caused by operational accident or carelessness. Sometimes it results from the release of internal stresses when

the tree is cut ; such splits are usually called "checks."

Occurrence.—The pecans—especially bitter pecan—and the hickories are likely to split at any time

because of release of internal stresses after cutting:

eottonwood and willow often split badly at the peak

of the growing season. Accidental splits can, of

course, happen, to any species, but most trouble is encountered in the pecans, the ashes, the hickories, and

the red oak group.

Significance.—By definition, superficial minor splits

can be disregarded. In factory logs, splits extending

more than one-fifth the diameter into the log are defects even though the portion of the lumber ruined be

scaled out. In tie and timber logs, splits on the end

which do not extend lengthwise more than 5 inches

beyond the trimming allowance can be disregarded.

FIGURE 32.—Split.

Other splits must be considered as defects. In localuse logs, splits can be disregarded.

Surface Rise

Definition.—A surface rise is a notable smooth undulation in the surface of the log or tree bole which

gradually tapers back in all directions to the normal

contour (fig. 33). Because of the nature of this abFiGURE 33.—Surface rise.

22 Agriculture Handbook No. 4, U. S. Department of Agriculture
normality, there can be no minimum height specification other than the ability of the eye to notice it. One

with the maximum height, however, has a taper of

1 in 6. When the taper is steeper, the abnormality is

classed as a bump (p. 7). A surface rise is usually

the eíTect of a small limb stub, a cluster of adventitious

buds, or a deeply buried knot. Sometimes a rise reflects an earlier crook in the stem.

SiiiTiificance.—Because the underlying lumber defects are so deeply buried that it is impractical to assess their degrading influence with consistent accuracy,

surface rises can be disregarded as log defects in logs of

all types. It is important to differentiate between a

surface rise and a bump, because the latter is an important log defect. This is particularly hard to do

when skidding has rubbed off some of the bark.

Wounds

Definition.—Wounds are openings in the bark that

expose sapwood and sometimes the heartwood (figs.

34 and 35). Wounds may be either new or old. A

new wound is essentially a surface injury in which the

exposed adjacent sapwood is apparently sound and

around which there is not more than 1 year's callus

formation. An old wound is an injury generally over

F-'155604

FIGURE 34.—New wound.

Log Defects in Southern Hardwoods

FIGURE 35.—Old wound.

1 year old, still completely open or only partially

healed over. It is generally characterized by unsound

sapwood, local hollow, much callus tissue, insect damage, and often stained or actually rotten heartwood.

Significance.—In a new wound, deterioration is

usually not serious, for any apparent insect damage or

stain will be quite superficial. Therefore, under most

conditions and for all types of logs, new wounds can be

disregarded as log defects. However, in the southern

lowlands and with such species as sweetgum, hickories,

magnolias, and basswoods, early deterioration is apt

to occur; if this enters the milling frustum, a new

wound must be considered a log defect in factory logs

but can be disregarded in others.

The seriousness of an old wound varies considerably

with locality and with species. In some species in

northern latitudes, exposed heartwood may completely

heal over before serious injury occurs. As with other

abnormalities associated with stain, rot, and insect

damage, the affected area is a log defect in both factory

logs and tie and timber logs, except in the rare cases

where it is superficial. In the factory logs, even if

cull deduction is made to cover the area involved in

worthless wood, the area will stop a cutting. Old

wounds can be disregarded in local-use logs.

23
LOG END ABNORMALITIES AND IMPERFECTIONS

The log abnormalities discussed heretofore have

been those visible on the surface. As has been pointed

out, these usually reflect imperfections in the wood, the

cross sections of which may show in the end of the

log. For example, on the ends can be seen the effects

of bird peck, of grub work, of extreme rot, of knots,

bark pockets, wounds, seams, flutes, and many other

surface abnormalities. These and similar blemishes

for which there arc surface indications are not reconsidered in connection with so-called "end abnormalities," with one exception. This is grub channels,

which arc the cross or longitudinal sections of the channels of wood-boring insects which make definite and

recognizable exit holes on the surface.

The log end may also reveal imperfections which

normally have no surface indicators (log defects).

These are the so-called hidden defects, and are those

which demand local experience for their appraisal in

standing timber.

Many of these end features are somewhat difîerent

from other product defects in that they are often admitted to a certain degree in the products and in that

their degrading effect is often based on concentration

rather than presence alone. Sometimes their efl^ect

is covered by special grades which admit the blemish

without qualification, but which bring a reduced price.

Their location, too, is important. Some which occur

in the heart center only may be more or less disregarded

in one type of log. In another type of log, the same

imperfection in the same position will mean a complete culling.

Many of these features are difficult to judge because

they are found on one end of the log only and the

observer must use considerable judgment in determining how far into the log the blemish persists. Many

are in the class of the scalable defects, and in judging

their significance as a log defect, the relation to the

particular product for which the log is best suited must

be carefully considered.

Dote

Definition.—Dote is an early stage of decay. The

wood is discolored and weakened, but does not lose its

structure (fig. 36).

Occurrence.—Dote can be present in all species,

although in woods of low density, such as the magnolias, túpelos, or swcetgum, it passes rapidly into

actual rot.

Siiinificance.—In both scaling and manufacturing,

dote is less consistently recognized and taken care of

than is rot (p. 28). There are two generally recognized phases of dote—slight and advanced. The first

FIGURE 36.—Dote.

may have little effect on the strength of the wood,

whereas the latter weakens it greatly. Advanced dote

is generally scaled out, particularly if extensive or if

found outside the heart center. In factory logs, dote

within the heart center may be disregarded, whether

scaled out or not, but dote outside the heart center is

a defect whether scaled out or not. In tie and timber

logs, dote is a defect, particularly when found in the

heart center. Doty areas may be disregarded as log

defects in local-use logs provided deduction for them

does not exceed that allowed for the class by cull

deduction.

Double Pith

Definition.—When a tree bole forks and a log is cut

just at the base of the fork, the end of the log will seem

swollen and the top will have two separate pith centers,

often separated by a bark pocket. This condition is

called double pith (fig. 37).

24 Agriculture Handbook No. 4, U. S. Department of Agriculture
Significance.—Double pith leads to cross grain in

sawn products, together with a split or potential split

from the bark pocket. The general approximate

effect is that of two large knots. In factory logs, double

pith is not a defect; however, the related seam and

any enclosed bark should be treated as in the case of

fork (p. 11). In tie and timber logs, double pith is a

defect. In standing timber, double pith may be disregarded if the section including it can be cut out so as

to leave logs of sufficient length to fulfill the minimum

requirements of the log type. Double pith is not a defect in local-use logs.

FIGURE 37.—Double pith.

Grease Spots

Definition.—Grease spots are limited but conspicuous shadowy areas with a dirty "greasy" look (fig. 38).

They are black, brown, or green in color. The wood

appears to be impregnated with a dirty oil.

Occurrence.—Grease spots occur principally in

chestnut and overcup oak and very occasionally in

cow and white oak. They arc generally found in timber on poor sites or with a bad fire history. In overcup oak, they may be related to very small pin worm

damage.

Significance.—In factory logs, a small number of

grease spots may be disregarded. A conspicuous conFiGURE 38.—Grease spot.

centration * of grease spots that prevents the lumber

from reaching the highest grade it would otherwise be

qualified for is considered a defect. In tie and timber

and local-use logs, grease spots can be disregarded.

Grub Channels

Definition.—Grub channels are round holes or irregular channels of varying length, from % inch to 1

inch wide (fig. 39). They are the result of woodconsuming grubs that hatch from eggs laid in the log

or living tree and work their way to the surface.

The holes are cross or longitudinal sections of the

channels.

Occurrence.—A single hole or channel may show,

or the end of the log may be literally riddled. Although grub channels may occur in any species, they

are found most often in the oaks, particularly in overcup oak, chestnut oak, and the water oaks. As discussed under insect-caused overgrown abnormalities

(p. 18), species-site relationships are important clues

to their occurrence.

Significance.—When grub channels are not concentrated or when a concentration is confined to the heart

* Conspicuous concentration is defined as occupying, in any

quarter of the log, more than one-half the area between the

heart center and the bark.

Log Defects in Southern Hardwoods 25
FIGURE 39.—Grub channels.

center, grub channels may be disregarded in factory

logs. Careful search, including thorough examination

of the surface, should be made to be sure that the concentration is so confined. When it is not, it is a defect.

In extreme cases, and when found in conjunction with

other defects, grub channels may cause complete culling of the log. In tie and timber logs, concentration of

grub channels in any portion of the log is a defect.

Grub channels can be ignored in local-use logs.

Gum spots

Definition.—Gum spots are accumulations of gumlike substances occurring as small patches, streaks, or

pockets. They may be related to bird peck or other

injury to the growing wood, or as in svvcetgum, may

be simply impregnations of the wood fibers, related to

physiological disturbances.

Occurrence.—Gum spots are found chiefly in black

cherry and swcetgum.

Significance.—In factory logs, gum spots are defects

when found in conspicuous concentration, for they reduce otherwise higher grades of lumber. A few spots

are admitted into clear cuttings and may be disregarded. Gum spots arc not defects iti tie and timber

logs and local-use logs.

Loose Heart

Definition.-—Loose heart is the tangential separation

of fibers along a growth ring at the heart center or

core of the log, in an area generally not over 6 to 12

inches in diameter (fig. 40).

Occurrence.—Loose heart is likely to be found especially in pecan and honey locust, and in ovcrcup,

chestnut, scarlet, and the water oaks.

Significance.—The area affected is definite, and must

be considered defective. When loose heart is confined to the heart center, it may be disregarded as a

defect in factory logs. Although the volume yield will

be greatly reduced through culling the affected section,

the loose heart will in such cases have a minimum

effect on average lumber grade yield. Loose heart

prevents taking a tie or timber out of the center portion of the log, and is a defect in logs designed for

this use. If the cull is not too great, loose heart may

be disregarded in local-use logs. Frequently, loose

heart derives from the release of crooked, suppressed

FiGUKi; 40. Loose heart.

saplings and follows the original stem form. Thus,

it may have a disastrous effect on small, crooked, or

sweepy logs, often necessitating complete culling.

Mineral Streak {Mineral Stain)

Definition.—Mineral streaks and stains are abnormal

discolorations—black, blue, brown, or olive-green—

usually in variegated or streaky patches (fig. 41).

Occurrence.—They are very conspicuous in soft

maple, hard maple, yellow-poplar, willow, and the

magnolias. They arc found generally throughout the

oaks, especially the water oaks, and particularly on

poor sites.

Significance.—In factory logs, they are a defect

when in conspicuous concentration outside the heart

center. A small amount may be disregarded. In the

maples and magnolias and in yellow-poplar, mineral

stain itself is not a lumber defect. Heavy concentrations, however, are usually associated with fine check

26 Agriculture Handbook No. 4, U. S. Department of Agriculture
so small that they could oasily be overlooked if it were

not for accompanying faintly discolored threads or

spots.

Occurrence.—They arc most prevalent in, but not

confined to, post oak, soft maple, ovcrcup and chestnut

oaks, ashes, and yellow birch. Black cherry, elms,

hickories, pecan, yellow-poplar, beech, sweetgum,

túpelo, magnolias, cottonwood, and willow are relatively free. When pin worm holes occur, they are invariably numerous: practically all of the wood in the

log will be aflcctcd.

Significance.—In factory logs, pin worm holes arc

defects. As with spot worm, special grades of lumber

with lowered value are used for the species in which

occurrence is most common. Pin worm holes may be

disregarded in tie and timber and local-use logs.

Ring Shake

Definition.—Ring shake is a tangential separation of

the wood fibers along the annual rings (fig. 43).

FIGURE 41.—Mineral streak and stain.

and shake, which arc defects. Mineral streak and mineral stain can be disregarded ¿M tie and timber and

local-use logs.

Pin Worm Holes

Definition.—These are small round holes, always

somewhat less than one-sixteenth inch in diameter

(fig. 42). Certain types are exceedingly minute.

Those found in some species, notably overcup oak, are

'^^i;*^^p^^*

FIGURE 42.—Pin worm holes.

Log Defects in Southern Hardivoods

FIGURE 43.—Ring shake.

Sometimes it is confined to definite sections along the

outer rim of wood, sometimes it is confined to the

center, and sometimes it is found all through the log.

Important ring shake is often so fine as to be invisible

in green wood, and shows up only when the wood is

dry.

27
Occurrence.—Although ring shake is definitely related to species, it is not found on all trees of any

species. On the other hand, it may be found in some

trees of every species. It seems especially prevalent

in overmature, leaning, and sweepy timber. A serious

butt injury to a tree may lead to ring shake. As good

second-growth timber stands develop, the occurrence

of ring shake will be greatly reduced. Today, however, much of the old-growth bitter pecan is shaky.

Ring shake is also serious in sycamore, túpelo, elins,

and overcup and chestnut oak.

Si¡inifieanee.—In factory Ions, ring shake confined

to the heart center or to definitely localized areas in the

periphery can be scaled out. Ring shake confined to

the heart center is not a defect, but peripheral ring

shake is a defect because it will stop cuttings. When

ring shake is general throughout the log, it is a good

reason for complete culling. It is a defect in tie and

timber logs. Localized shake can be disregarded in

local-use logs up to the point where the cull deduction

for it exceeds that permitted in the class.

Rot

Definition.—Rot is an advanced stage of decay in

which the structure of the wood has been broken down

and its usefulness ruined (fig. 44).

FIGURE 44.—Rot.

Occurrence.—There is no particular relationship to

species. Rot generally occurs in definite areas. A

frequent location is the center of the tree or log. Other

rotten areas resulting from wounds or knots are found

in the outer rim of wood.

Significance.—The significance varies with use and

location. In factory logs, rot confined exclusively to

the heart center can be overlooked as a log defect.

The affected section will, of course, be culled out in

the scaling. Even though they arc scaled out, peripheral rotten areas are log defects if they occupy over

one-half the cross-sectional area in any quarter between the heart center and the bark.

I?i tie and timber logs, center rot is a defect which,

except in large diameters, probably will eliminate

the log from the class. Peripheral rot is also a defect,

unless it is so superficial that it will extend into the

included tie or timber in only a few minor spots which

are not more than 3 inches deep. In local-use logs,

rot can be disregarded as a log defect provided the cull

deduction does not exceed the limits for the class.

Shot Worm Holes

Definition.—Shot worm holes are clean-cut round

holes about one-eighth inch in diameter ( fig. 45 ).

They are generally concentrated in and about doty or

rotten heartwood, especially open butt wounds.

Occurrence.—They are commonly found in oaks,

hickories, ashes, and occasionally in sweetgum heartwood.

Significance.—Since shot worm holes are generally

associated with rotten wood, they are not a defect in

factory logs if confined to the cull section. However,

if they extend beyond the bad section and increase the

area to be culled, they become log defects. They can

be disregarded ¿n tie and timber and local-use logs if

the allowance for associated cull is adequate.

Soak

Definition.—Soak is a moderately discolored area,

dirty mustard yellow, bleached brown, or dull gray

in color. The wood looks dull, dead, rough, and

spongy, and often water-soaked or weathered. Although it is considered by some as incipient decay,

soak actually is not accompanied by a softening of the

fibers; sometimes, in fact, they may be embrittled.

Occurrence.—It is most common in overcup and

water oaks on poor sites.

Significance.—Ordinarily, no cull deduction is made

for soak. In factory lumber, it is regarded as equal

28 Agriculture Handbook No. 4, U. S. Department of Agriculture
•^-

í

It

wx

J

'^-

F-455617

FIGURE 45.—Shot worm holes and associated rot.

in effect to mineral stain or localized slight dote.

When heavy enough to be so considered, soak becomes

a factory Ion defect, but can be disregarded in tie arid

timber and local-use logs.

Spider Heart

Definition.—Spider heart is a multiple radial separation of the wood fibers starting at the pith center

and running out in at least three directions (fig. 46).

Occurrence.—Spider heart is related to species, size,

and degree of maturity. It is common in scarlet,

ovcrcup, and water oaks, and is likely to be found in

chestnut oak. The most important occurrence is in

large, fully mature or overmature trees.

Significance.—Spider heart will ruin the products

in which it occurs. If it is confined to the heart center, it is not a defect Í7i factory logs and in local-use

logs. When it extends beyond the heart center in

factory logs and when it occurs to any degree in tie and

timber logs, it is a log defect.

FIGURE 46.—Spider heart.

Spot or Flag Worm Holes

Definition.—Spot or flag worm holes arc clean-cut

holes about one-thirty-second to one-sixteenth inch in

diameter, typically occurring in pairs (fig. 47). They

arc invariably surrounded by an oval or elongated

stained or (in oaks and elms) bleached area or "flag."

Occurrence.—In red and silver maple and post oak,

spot worm will be found in almost every tree over the

entire range of the species, but intensity will vary from

tree to tree. In soft elm, beech, chestnut oak and

white oak, occurrence is spotty and some localities

are entirely free. White oak over most of its range

is free, but damage is likely to be found on sites which

are dry or lacking in lime.

FIGURE 47.—Spot or flag worm holes.

Log Defects in Southern Hardwoods 29
Significance.—In factory logs, spot worm holes with

their arrompanying flags arc defects except in heavily

damaged oaks and maples. In these species, the lowered value of such lumber is recognized by special

grades and the holes need not be considered as log

defects when utilization practice is to use such grades

(WHND: worm holes no defect). Spot worm can

be disregarded in tie and timber and local-use logs.

Wind Shake

Definition.—Wind shake is a single radial split extending to both sides of the pith (fig. 48). Sometimes

it is confined to the heart center, but often it will go

to the perimeter of the heartwood. Damage is usually

most serious in butt logs, but many times the split extends the entire length of both the butt and upper logs.

Occurrence.—Wind shake is most serious in black

oak, southern red oak, scarlet oak, and northern red

oak growing on upland sites in the south central United

States west of the Mississippi River. It is more prevalent in older trees than in the younger ones, and it is

possible that, as site conditions improve and good

second-growth timber stands develop, the occurrence

will be greatly reduced. Wind shake is also found in

some of the white oaks, particularly chestnut oak, on

upland sites throughout the Appalachian region and

the remainder of the South. It becomes serious along

about the middle of slopes and is worst on the ridge

tops.

FIGURE 48.—Wind shake.

Significance.—In factory logs, wind shake can be

scaled out, and that which is confined to the heart

center is not a defect. Where it extends to the perimeter of the heartwood in logs where the sapwood

band is narrow, it is a defect because it will stop cuttings. Most wind shake is so serious that it disqualifies the log for a tie or a timber log. Wind shake may

be disregarded in local-use logs unless it is severe

enough to cause the log to split open in handling.

GENERAL APPEARANCES WHICH WARN THAT LOG DEFECTS

SHOULD BE SOUGHT

Thus far, the discussions have been concerned with

specific features of logs which, if properly identified

and evaluated, are guides to accurate log appraisal.

Sometimes, however, a log or tree can be evaluated by

general appearances, or warning signs may herald the

presence of specific log defects.

Signs in Standing Timber

There is a definite relationship between timber quality and site condition or past history of the stand. Poor

site, past fire damage, and overmaturity are often clues

to the presence of such defects as insect damage, shake,

or stain.

General condition and appearance of individual

trees in any given locality serve either as a specific guide

to lumber defects which have no other outward indication of their presence (shake or mineral stain, for

example), or as a warning to intensify search for important log defects (such as bark distortions) which

cannot be seen at a glance. To appraise basic difTerenccs in appearance of standing timber requires training and familiarity with each species over a wide range

of conditions. But keen observation and practice will

enable one to determine and recognize the characteristics of sound, healthy trees, and, by comparison, those

of trees likely to be defective.

30 Agriculture Handbook No. 4, U. S. Department of Agriculture
Obvious clues to decadence are stagheadedncss,

bad fire scars, and large, open wounds. Less conspicuous but of the same nature arc dry tops, dead

limbs, healed scars, and rotten knot holes, often overgrown except for a gaping, oozing center. Such features indicate decadent timber which may carry parevidence of lack of vigor (dead limbs, thin top, and

poor foliage), are among these (fig. 49).

In general, abnormally dark or abnormally light

bark is a bad sign. In hickories and cherrybark oak

and the water oaks, early stages of deterioration are

evidenced by a darkening of the bark, usually accomFiGURE 49.—Good, medium, and poor conditions of

ticularly the inconspicuous defects and unheralded

ones like stain and spot worm. When such gross features occur, defects are very likely to be present in

damaging proportions. Evidence of such defects in

the form of small overgrowths, often partially hidden

under extended but broken bark scales, will generally

be plentiful and easily located upon close examination.

In addition to the gross features indicating decadence, less obvious general appearances are very important signs of probable defects. Color, thickness,

and configuration of bark, particularly if coupled with

F-455618-20

three willow oak trees, as indicated by bark characteristics.

panied by a thickening and roughening. In extremely

advanced stages of deterioration, the color trend in

these species reverses, and the bark bleaches out to a

dead, light gray and scales off to some extent. In

species with bark normally soft and corky, such as

yellow-poplar and sweetgum, the darkening is accompanied by a "jjlating" and smoothing out of the

bark. On the other hand, defective white oak timber

in all stages of deterioration is indicated by a lightening of color and a thinning and scaling off of bark. In

all species, bark looks dry and lifeless when vigor is

lost. Where such conditions attract attention, close

Log Defects in Southern Hardwoods 31
inspection is necessary if important log defects are not

to be overlooked. The relation of timber condition

to appearance is definite, and sometimes so extreme

and positive that an experienced observer has no difficulty in appraising the degree of deterioration solely

on this basis.

However, poor general appearance of bark is not an

absolute indication of defect of any specific kind.

Yellow-poplar, sweetgum, basswoods, and túpelos are

rarely subject to insect attack (yellow-poplar in some

localities is apt to be severely attacked by ambrosia

beetles, the damage being referred to at times as spot

worm, grease spots, black hole, calico poplar). In

these species, poor bark appearance generally indicates

slow growth or approaching maturity, or, if localized, a

cull section. In fact, an area of poor bark in these

species is as good a sign of cull as a butt or stem bulge.

On the other extreme are the oaks and the hickories.

Here poor appearance, although also a sign of lower

vitality, does not reliably indicate specific location or

extent of cull. It is, however, almost an invariable clue

to hidden or obscure bark distortions. Close inspection of the bark of poor trees of these species will often

reveal scattered, medium-size, dry holes that penetrate

the bark scales but do not lead into the wood. It will

also reveal that any abnormal roughening is due to

numerous horizontal breaks or cracks in the bark ridges

or scales. In the bark cracks and under the scales containing the holes will generally be insect-caused log

defects (fig. 50). In most cases, other log defects will

have been noted before the examination has gone that

far.

In other species, such as sycamore, and the ashes and

maples, the significance of bark appearance is quite

variable. In all species, however, poor or abnormal

appearance should lead to intensive search for log

defects.

At least two types of local bark discolorations deserve

notice. One is the so-called "tobacco juice" exudation—a small, usually damp, dark brown spotch with

a drying gray border, found up and down the bole. It

is unmistakable evidence of fresh insect damage which

can be disregarded unless the splotches are very numerous or are accompanied by bark distortions typical

of long-established infestations.

The other type of local discoloration is a large patch

or streak running down the stem and originating at a

broken top or an open wound or knot hole in the main

sti-m. When coming from a broken or hollow top of the

major stem, the discoloration is usually an overflow of

rain water. When the discoloration originates elsewhere than in the top, it is caused by water seeping

from a pocket of decay. However, the mere fact that

it is seeping or running usually indicates that decay

is not far advanced, or at least that the cull section is

not an extensive hollow. Ordinarily, the decay will

not pass the next lower fork or body node. However,

when such a situation is found on the merchantable

stem, it is a log defect if not cut out.

F-45562I-22

FIGURE 50.—In the oaks and hickories, holes like this one

(left) call for careful search for the the actual defect. The

hole was made by an emerging grub, and beneath the scale

{right) is the overgrown evidence of his presence.

Signs on End of Log

The lumber defects underlying surface abnormalities (log defects) sometimes show up in the end of the

log. This fact is particularly useful where logging

operations have scraped the log so that overgrowths,

in particular, are hard to find. If the previous inspection has not found surface indication of the associated lumber defects, grub channels and bark pockets

in the end of the log call for a rccheck of the surface.

The ends of very large logs may give positive indication of heavy insect infestation, the external signs of

which have been overgrown so long as to be obliterated.

In such cases, because the afl'ected area outside of the

heart center represents such a large part of the highgrade lumber, the exposed defects themselves must be

evaluated in appraising quality. Otherwise, such end

features merely warn that a recheck should be made.

32 Agriculture Handbook No. 4, U. S. Department of Agriculture
CLASSIFICATION AND EVALUATION OF LOG ABNORMALITIES

Classification

It has been shown that certain abnormalities which

indicate wood blemishes may be disregarded as log defects under certain conditions in any type of log, and

that some may never be disregarded. The latter

group needs no further definition; the first, however,

requires some explanation.

In standing timber, an abnormality may be disregarded if it will not be included in the logs that are

€ut out.

Size and character of the abnormality are other important conditions, particularly in tie logs. Concentration is another factor important in judging significance, particularly of end defects, and especially in

factory logs. Position of defect within the log is another consideration. This works two ways. Defects

and imperfections confined to the heart center of factory logs are minimized; in tie and timber logs, they

are maximized, particularly in small and medium

diameters. In local-use logs there are few degrading

or disqualifying defects as in other logs. The important items are unsound scalable defects which are

taken into account only in the aggregate to determine

net scale and which, if excessive, disqualify the log.

Table 1 classifies the defects that have been discussed on the preceding pages.

Evaluation

Heretofore, each defect has been discussed independently in relation to potential use of piece, but not

in relation to other defects. The implication may have

been that each defect bears equal weight as a quality determinant; i. e., a small knot is equal to a large

knot; a large knot is equal to a seam; a seam is equal

to a burl; and a burl is equal to a concentration of grub

channels in the end. With local-use logs, this question is unimportant because there are so few significant log defects.

For tie and timber logs, the implication that one

defect is of equal weight with another will also probably hold, for the major influence of log defects appears to be either to admit or exclude the logs from the

class. For example, the effect of an extremely large

knot or of loose heart would be equal in that either

would render the log unsuitable for tie and timber use.

In factory logs, however, the situation is less simple.

Here the primary effect of defects is to limit clear cuttings. A secondary effect is directly to degrade boards

which, without the particular blemishes, would be of

higher grades. Relation of defects to log size is important because it is common practice to eliminate or

segregate lumber defects in wide boards by ripping.

The effect of blemishes can be minimized in this way

if the resulting boards are within the width limit for

the grade specified in the rules (see appendix, p. 35).

In principle, a very tiny knot is equal in degrading

effect to a large knot. However, a run of factory logs

may yield enough wide boards, from which small knots

can be ripped out, so that the mere presence of the

knots in the log may not actually mean low-grade

boards. Because of this possibility, it may be necessary,

in logs of large diameters, to discount log defects

which indicate very small knots, whereas full weight

may have to be given to large knots in logs of all sizes.

Other defects in factory logs may have the effect of

degrading all of the lumber in the log to a very low

point. Slight bird peck, for instance, might be disregarded as a defect in logs otherwise defect-free.

If, however, bird peck were very heavy, the procedure

might be to give it the ultimate significance and consider that even in the absence of all other log defects,

the bird peck would relegate the log to the lowest factory grade, if not to a lower class.

It is obvious, however, that the basis for evaluation

of defects, i. e., whether their effect is partial or full, or

whether they are considered individually or en masse,

must lie in a log grading system which will not only

evaluate individual log defects, but will also relate

them to the distribution or size requirements of the

product specification and to the other major quality

determinants such as size, crookedness, or position of

the log in the tree. Such a system will also segregate

the various use classes and thus give a basis for judging whether abnormalities are or are not log defects.

Log Defects in Southern Hardwoods 33
TABLE 1.—Classification of log abnormalities

LOG SURFACE ABNORMALITIES

Abnormalities

Adventitious bud clusters. . .

Bulges:

Butt

Stem

Bumps:

High

Low

Burl

Butt scar

Butt swell

Canker

Conk

Flanges . .

Flutes

Fork

Holes:

Large

Medium:

Ant, fresh

Ant, old

Birds, light

Birds, heavy

Grub

Increment borer. . . .

Tap

Small

Knots:

Sound

Unsound

Limbs

Overgrowths:

Knots and bark pockets.

Insects

Bird peck

Bark distortions

Seams

Splits

Surface rise

Wounds:

New

Old

Factory logs

Defect.

0).

0).

Defect....

«

Defect

0^)

No defect.

0)

Defect

No defect.

0)

0)

Defect.

No defect.

Defect....

No defect.

Defect

do...

do...

do...

«

Defect..

do.

do.

do...

do...

do...

do...

0)

{')

No defect.

do...

w.

Tie and timber logs Local-use

No defect.

0).

0).

«

«

Defect

0')

No defect.

(0

Defect....

No defect.

(')

0)

«.

No defect.

....do...

....do...

....do...

....do...

....do...

....do...

....do...

«.

«.

«.

«

No defect.

do...

do...

«

w

No defect.

do...

w.

No defect.

Do.

Do.

{').

No defect.

Do.

Do.

Do.

Do.

Do.

Do.

«.

No defect.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

No defect.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

LOG END ABNORMALITIES

Dote

Double pith

Grease spots

Grub channels

Gum spots

Loose heart

Mineral streak and stain

Pin worm holes

Rot

Shake:

Ring

Wind

Shot worm holes

Soak

Spider heart

Spot or flag worm holes.

0)....

D....

D....

Defect.

Defect.

Defect.

Defect....

(')

No defect. c)

No defect.

Defect

No defect.

do...

Defect....

do...

....do...

No defect.

do...

Defect

No defect.

No defect.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

Do.

1 Defect if not cut off.

2 Defect if large.

^ Defect if certain species involved.

^ Defect if not superficial.

5 Defect if large and deep.

^ Defect if not confined to heart center.

^ Defect if concentrated.

34 Agriculture Handbook No. 4, U, S. Department of Agriculture
APPENDIX

TABLE 2.—Basic specifications for standard hardwood lumber grades

[Adapted from the rule book of the National Hardwood Lumber Association, Chicago, January 1949. Published by permission of

the National Hardwood Lumber Association.]

Minimum requirements

Grade

Length i Width

Yield of

rough lumber

in clear-face

cuttings

Size of cuttings Cuttings 2

Firsts and seconds

Feet

8

6

4

4

Inches

6

4

3

3

Percent

83/3 A" X 5' or 3" X 7'

Number

1-4.

Selects ^

1 Common 662/3

50

A" X 2' or 3'' X 3'

3'' X 2'

1-5.

2 Common 1-7.

Sound w^ormv ^

3A Common 4

4

3

3

33/3

5 25

3'' x2'

1/'' X variable length

No limit.

3B Common To give 36 square inches.

1 Percentage of short lengths limited by grades; e. g., in firsts and seconds, only 15 percent can be 8 feet to 9 feet; in 2C, 10

percent can be 4 feet to 5 feet.

2 Number varies with surface measure (s. m.) of piece; e. g., IG with s. m. of 5 feet to 7 feet, 2 cuttings allowed; in IC with s. m.

of 11 feet to 14 feet, 4 cuttings allowed.

3 Better face is seconds; reverse side of cuttings sound. Better face is seconds; reverse side of board No. 1 G.

^ Full log yield of IC and Better, with worm holes, knots, etc., not over % inch and stain, admitted into cuttings.

5 Sound cuttings. Lumber is suitable for low-grade crating and dunnage.

Indications of Deterioration in Dead Timber

or Stored Logs

Since timbermen frequently are concerned with

dead trees, or with logs which have been left in the

woods or stored for a lengthy period, it is important to

discuss briefly the indications of deterioration found

in such material, so that they can be distinguished from

those found on live trees or freshly cut logs.

Hardwood logs, particuarly in the southern lowlands, are highly susceptible to deterioration through

the action of insects and fungi. In summer, logs left

more than 2 weeks begin to deteriorate so rapidly that

even "hot logging" will not keep some species from

damage. Operations for hickory and persimmon for

dimension specialties are frequently suspended in late

spring and early summer because of borer activity.

For all other species, hot logging is a necessity during

this period. In the deep South, insects may cause

damage the year round.

Among the first to infest logs are the ambrosia

beetles. They start working almost at once in the sapwood, on the ends, or on spots where the bark has been

knocked off. Later, they may also go through the

bark and attack the remaining sapwood and sometimes

the heartwood. Their holes are so very small that it is

easier to spot a pile of flour-like "frass" than to see the

holes themselves. Ambrosia beetles are particularly

bad in sweetgum, maples, oaks, and yellow-poplar.

Their work degrades the lumber. Like shake, any

indication of it ("worms" in the trade) generally

renders a shipment suspect in the eyes of the buyer,

and puts the seller in an awkward position.

Another insect, especially bad in the ashes and

hickories, pecan, and persimmon, is the round-headed

borer. The grub of this insect causes degrade and

often outright culling by making medium-sized holes

throughout the wood.

Stain-causing fungi come simultaneously with, and

some are introduced by, the ambrosia beetles. The

first effect is a rather even sooty blue-gray or black

discoloration of the wood. Later, a felty surface may

develop. Stain proceeds from the ends and through

wounds. It does not develop rapidly under bark. In

early stages, stain does not degrade lumber, although

it affects its salability. In later stages, it definitely degrades lumber unless stain is specifically permitted by

the grading rules.

After stain corne "flowers." These are whitish,

yellowish, brownish, or grayish variegated mosaic

efflorescences, usually though not necessarily superimposed on the stain. They are evidence of a separate

fungus which causes decay. Since they are commonly accompanied by light mustard-colored or gray

Log Defects in Southern Hardwoods 35
bleached streaks in the wood, flowers are, in the trade,

considered as the beginning of dote and will not be

admitted into cuttings. It is general practice to trim

1 to 2 feet off the ends of boards cut from logs that

show flowers and yellow streaks on the end. Although

sweetgum and the túpelos are most susceptible to stain

and flowers, sapwood of most species will be attacked.

The water oaks are also hit hard.

On soft maple and on the hickories, elms, and hackberries, a fungus causing an inconspicuous internal

dry rot starts quickly. This fungus gives no surface

evidence of its presence until it has caused such advanced interior decay that the log is worthless. At

this time, the wood is weak, yellowish, exhibits black,

threadlike lines, and looks dry and bleached out.

The surface of the log may still appear sound, and

merely weathered. Other fungi betray their presence

by fruiting bodies (toadstools and brackets). These

generally indicate advanced dote and a high percent

of cull, if indeed the log is usable at all (fig. 51 ).

The ends of any logs left out in the weather will

check or split. The ashes, hickories, pecans, and overcup oak are prone to end-check throughout the year.

In other species, degree of end-checking varies with

the season. In good drying weather, end-checking in

cottonwood, the pecans, the hickories, and the oaks is

particularly bad. In general, end-checks are progressive, with the speed and severity related to rate of drying. In most logs of most species, they arc not serious,

for they generally go less than 1 foot into the log. On

logs of susceptible species, they may extend well into

the center and cause serious damage. Such extreme

checks are equal in cfl'ect to splits. The importance

of checks is also related to log size. Small logs may be

completely ruined by checks which in larger logs would

he unimportant.

FIGURE 51.—Brackets arc a sign that rot has made at least

the sapwood useless. The heartwood may remain sound

for a considerable time, but very careful examination is

needed to determine how far decay has spread.

Common and Scientific Names of Species Referred to in the Text

Lumber or local name '

Ash

Basswood

Beech

Birch, yellow

Blackgum

Blackgum, swamp

Cherry

Cottonwood

Cottonwood, swamp

Elm, soft

Elm,cedar

Sec footnotes at end of table.

Recognized common name ^ Scientific name "

Green ash Fraximis pennsylvanica lanceolata

White ash F. americana

Basswood; linden ^ Tilia spp.

American beech Fagus grandijolia

Yellow birch Betula lutea

Black túpelo; blackgum Nyssa sylvatica

Swamp túpelo; swamp Ijlack lupelo ^. . . . N. sylvatica biflora

Black cherry Prunus serótina

Eastern cottonwood ; eastern poplar '. . . . Populus deltoides

Swamp cottonwood; .swamp poplar ^. . . . P. heterophylla

American elm Ulmus americana

Cedar elm U. crassijolia

36 Agriculture Handbook No. 4, U. S. Department of Agriculture
Common and Scientific Names of Species Referred to in the Text—Continued

Lumber or local name ^ Recognized common name ^ Scientific name ^

Hackberry Hackberry; common hackberry ^ Celtis occidentalis

Sugarberry; sugar hackberry ^ C. laevigata

Hickory Hickory Carya spp.

Honeylocust Honeylocust; common honeylocust ^ Gleditsia triacanthos

Magnolia Magnolia... Magnolia spp.

Maple, soft Red maple Acer rubrum

Silver maple A. saccharinum

Maple, hard Sugar maple A. saccharum ^

Oak, black Black oak Quercus velutina

Oak, burr Bur oak Q. macrocarpa

Oak, cherrybark Cherrybark oak ^ Q. Jalcata leucophylla ^

Swamp red oak Q. Jalcata pagodaefolia

Oak, chestnut Chestnut oak Q^. montana

Oak, chinquapin Chinkapin oak (¿. muehlenbergii

Oak, cow Swamp chesnut oak Q^. prinus

Oak, Delta post Post oak Q^. stellata

Oak, forked-leaf white White oak Q. alba

Oak, laurel Laurel oak Q^. lamijolia

Oak, northern red Northern red oak Q. borealis

Oak, Nuttall Nuttall oak (¿. nuttallii

Oak, obtusa Diamondleaf oak Q. obtusa

Oak, overcup Overcup oak Q^. lyrata

Oak, pin Pin oak Q^. palustris

Oak, post Post oak Q. stellata

Oak, scarlet Scarlet oak Q^. coccinea

Oak, shingle Shingle oak Q^. imbricaria

Oak, Shumard Shumard oak (¿. shumardii

Oak, southern red Southern red oak Q^. Jalcata

Oak, swamp white Swamp white oak Q. bicolor

Oak, turkey Turkey oak Q. laevis

Oak, water Water oak (¿. nigra

Oak, willow Willow oak Q^. phellos

Pecan, sweet Pecan Carya illinoensis

Pecan, bitter Water hickory C. aquatica

Sapgum Sweetgum Liquidambar styraciflua

Sycamore American sycamore Platanus occidentalis

Tupelo Water túpelo Nyssa aquatica

Walnut Black walnut Juglans nigra

Willow Black willow Salix nigra

Yellow-poplar Yellow-poplar; tuliptree ^ Liriodendron tulipijera

1 According to local usage.

2 According to "Check List of the Native and Naturalized Trees of the United States, Including Alaska." U. S. Forest Service,

Washington, D. G. 325 pp. Rev. ed. 1944.

3 According to "Standardized Plant Names," by H. P. Kelsey and W. A. Dayton for Amer. Joint Com. on Hort. Nomencl.

J. Horace McFarland Co., Harrisburg, Pa. 675 pp. 2d ed. 1942.

Log Defects in Southern Hardwoods 37

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