THE ERECT OF THE OAK HILT FUNGUS UPON OAK HOOD DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy In the Graduate School of the Ohio State University WILLIAM tf.BRANDT, BJU, M.Sc. The Ohio State University 1954 Approved ty: 'f e w i ACKN0HLEDGEMENT5 The writer wishes to express his deepest gratitude to Or* W.D. Gr^r for counsel and adrioe during this investigation, to Or* H*C* Young for suggesting the problem, to the Ohio Agricultural Exp­ eriment Station for sponsoring it, to the Statistics Laborstoxy at the Ohio State University for guidance, to the Department of Mechanics of the Ohio State University for adapting a machine to the purposes of the investigation and for use of the machine, to the Department of Electrical Engineering for use of an analytical balance and space in an air-conditioned laboratory, to the Forest Products Laboratory at Madison, Wisconsin, for advice and for the isolates of wood-rotting fungi used in Part U of the study, to George J* Bart and Oren W* Spilker for isolating associated fungi and procuring boards for blocks, and to maqy others who gave assistance and material aid* \ If) 107 ii CONTENTS Introduction ------------------------ 1 Part I. The Effect of the Oak Wilt Fungus on Oak Wood and on Sates of Decay ty sone Fungi Associated with It* Materials and Methods ----------------- 5 Results ------------------------ 16 Part II* Durability of Oak Wilt-Killed Oak* Materials and Methods ----------------- 24 Results ------------------------ 26 Summary —————————————————————————— 26 Literature Cited ---------------------- 29 Autobiograpty ----------------------- 30 -1- THE EFFECT OF THE OAK >.TLT FUNGUS UPON OAK HOOD INTRODUCTION During the course of oak wilt investigations, majy workers ob­ served what appeared to be a rapid loosening of bark on trees which hud died of the disease* This loosening and sloughing of the bark seemed much more rapid than on trees killed ty other agents such as lightning and girdling* These observations gave rise to suspicions that the wood of oak trees killed ty the oak wilt fungus decayed more rapidly than the wood of heal tty oak trees* If accelerated decay actually did occur, it would have been necessary to remove oak wilt- killed trees from the forest proportionately sooner than other timber; the manufacture of lumber from diseased trees would have to take place sooner, and there would possibly be serious doubts regarding the dura­ bility of the lumber thus obtained. This stu<fy was undertaken to attest to ascertain the direct and indirect effects of the oak wilt fungus (Endoconidiophora fagacearun Breti) upon oak wood, the direct effects being possible decay of the wood by the oak wilt fungus; the indirect effects a possible oak wilt- induced acceleration of the decay caused by other organisms* There are two distinct aspects to this wood decay problem: (1) the decay of standing timber and (2) the rotting of structural timber and lumber. These are due to the interaction of two factors: envir­ onment, and the fungus inoculum. The forest environ— nt includes widely—ranging physical conditions such as temperature, light, and moisture, which influence the kinds of fungi growing in the forest and -2- the amount of vegetative and reproductive growth of these fungi. These in turn determine the relative amounts of fungus inoculum to which a tree might be exposed and how fast the tree will decay if conditions permit it to become infected. The internal environment of the standing tree is usually much different from that of lumber; for instance, the moisture content of a standing tree is generally greater than that of seasoned lumber. In addition( the external environment of much structural wood is more uniform than the external environment of the wood of a tree in the forest. The effect of the interaction of ail these factors, as well as others, is that the fungi which usual ay inlect standing timber do not commonly cause decay of structural wood. No doubt a field study involving periodic testing of diseased oaks which were left in the woods would have given the most direct information with reference to standing timber. Such a study was not feasible in Ohio since it would have meant purposely leaving centers of infection scattered throughout the forest areas, a practice not deemed to be in the public interest. Instead, a laboratory investiga­ tion was undertaken in which an effort was made to subject oak wood to preliminary treatment with the oak wilt fungus or its products and then to subject it to infection ty fungi found to inhabit oak wilt- killed trees. Part I deal» with this work. The resistance of wood to decsy is termed durability. Therefore, insofar as structural timber is concerned, the primary interest is the relative durability of 1 timber from healthy trees and from oak wilt- -3- killed trees* The Forest Products Laboratory at Madison, Wisconsin, has developed certain methods of ascertaining the durability of oak wood ty me«tns of fUngi commonly found to be causal agents of the rot­ ting of structural wood* (Scheffer, et al* 1949) These methods, slightly modified, were employed in the experiments described in Part II of this paper* Little work appears to have been done upon the effect of non­ wood -destroying organisms on the durability of wood* Here are some comments from an early bulletin about chestnut timber: "Strength and Durability of Piscase-Killed Timber*" "Preliminary strength tests conducted by the Forest Service upon chostrmt killed by the bark disease indicated that sound wood from dead trees is fully as strong as wood fron healthy trees. Discase-kiLied chestnut seasoned on the stump is probably more durable than green-cut chestnut used unseasoned, owing to the former's comparative dryness* In 1910 a railroad in Pennsylvania rejected a shipment of chestnut ties from Long Island because they were cut from diseased trees. The ties were left piled on the right of way for three years, but upon reinapection in 1913 were found to be so sound that they were finally accepted." (Nellis, 1913). Baxter and Gill (1931) studied the rate of decay of chestnut blight-killed chestnut but not the rate of decay of non-diseaso-killed timber so a cougari son is not available from their work* Scheffer and Lindgren (1940) state, "The evidence indicates that whatever differences there nmy be are not of practical importance," in referring to the relative durability of fungus-stained sapwood and non­ stained sapirood* However, they mentioned some investigators who felt, on the basis of their own research, that stained wood was less durable, Prescott and Dunn (1949) state that, "Saprophytic types (bacteria) occassionally may increase the rate of decay ty fungi," but fail to -4- cite ary experimental evidence* There is some data concerning the effect of preliminary rotting by one fungus upon the rate of subsequent rotting ty another fungus. Findlay (193*;) found that subjecting wood to the preliminary decay of a brown rot fungus had no effect upon the rate of decay caused by a second brown rot fungus* Likewise, a preliminary rotting Ty a brown rot fungus had no effect upon the rate of subsequent rotting Ty a white rot fungus; but if a white rot fungus partially rotted the wood first, the rate of subsequent rotting ty a bro-n rot fungus was in­ creased. (Findlay, 1940)* Lehman and Scheible (1924) showed that a preliminary inoculation of wood with Coniophora cerebolla Pers* in­ creased the rate of decay caused Ty some other fungi. In 1943, Roth reported that incipient decsy in oak crossties and posts enhances the rate of decay as compared to the rate of decay of sound wood* - 5- PUtT I THE EFFECT OF THE OAK WILT FUNGUS ON OAK VOOD AND ON KATBS OP DECAY FT SOME FUNGI ASSOCIATED WITH IT MA1EBXALS AND METHODS: Teat Blocks The primary interest in this investigation was the rate of decay of dead oak trees in the forest* As stated in the introduction, a dir­ ect inrestigation was not desirable for reasons of sanitation* The obvious alternative to this, the comparison of the rate of decomposi­ tion of pieces of healthy* oak wood with the rate of decomposition of diseased** oak wood in the laboratory was thought not feasible because of the great amount of variation in decay resistance among individual trees* Unless this variation were eliminated, it would not be possi­ ble to infer whether axy differences resulted frou the effect of oak wilt or fToa the inherent variation present before testing was started* This variation oould hsve been overcome ty taking a large enough sample of oak trees; however, since snail blocks had to be used due to certain naterial considerations, a large enough sample would have in­ volved the cutting of dosens of oak trees in various parts of Ohio, a procedure which would have exoeeded the financial limitations of the project* Another possible method of overooming the variation is to take the test blocks from the same location in the same tree, extensive studies having indicated that such a procedure is valid* (Scheffer, et al* 1949) • Therefore this method was adopted* The major difficulty • heal tty — refers to aiy oak tree not infected ty the oak wilt fungus* ** diseased — aigr oak tree having mrmptoaut of oak wilt* - 6- iabartnt in this procedure is that ths blocks are sithsr ftos healthy oak trass or all frou diseased oak trass* To attempt to obviate this probloa, ths blocks vers out from a singla board of heart ty- oak wood, raadoaissd sad half wars inooulatsd with ths oak wilt fungus or trsatsd with