/} /7/ TO U.S. DEPARTMENT OF AGRICULTURE, Bl REA1 i IF PLANT INDUSTRY- (uvular No. 3. B. T. GALLOWAY, Chief of Bureau. SOME STEM TUMORS OR KNOTS ON APPLE AND QUINCE TREES. GEORGE G. HEDGCOCK, Scientific Assistant, [nvestigations of Diseases of Fruits. GOVEH-. N . 1908 DEPOSITORY Digitized by the Internet Archive in 2013 http://archive.org/details/tumorsorOOunit Bl Rl LI OF PLANT INDUSTRY. : : Galloway. • r: F. Woods. '■mi Pathology, Erwin F. Smith. Pathologist in Charg s - ~en Metcalf. Pathologist in C nd Plant :am A. Orton. Pathologist in I T. Swingle. siologist i- Cotton Breeding Investigations, Archibald D. Shamel and Daniel X. Shoemaker. Physiolo- - Archibald D. Shamel. Wightman W. Garner, and Err.-- 5 P. Har:: - iogist in Chr.:_ ■tant Plant Breeding Investigations. Thomas H. Kearney, SoU Bad and Water Purification Investigations. Karl F. Kellerman. Physiologist Bionoi ;s of Tropical and Subtropical Plants, Orator F. Coot. Bionomist Iture Investigations. Rodn-v i: - ;st in Charge. Crop Technol Plant ligations, Nathan A. Cohb. Crop Technol. - _ omic and Rat. ;;ie. Botanist in Chr.:- Farm Ma' "TiHiam J Spillman. Agriculturist in Charg M -- Horticult-: ■ :3.m W. T: S iperinter . Sugar Tovrnsend. Pathol . Hon Investigations. - ^-oneld. Agriculturist in Charge. Agriculture It, Agriculturist in Charge. - 5 B. 1 cert. 1 list i William A. Taylor and G. Harold Powell. Pohk - 5ta .^ard M. Byrnes. Superintendent. ■ i and Plant Introductio' -irchild. Agricultural Explorer in Charge. - V. Pip*r. Agrostologist in Charge. _ s'r.anahan. Crop Technologist in Charge. Pathologist in Charge. Plant Introduction Garden. Mayer. Expert in Charge. South Jen, Bro - "dward C Gre*-n. Pomologist in Ct - Farm- ttion Work. Seaman A. Knapp. Special Agent in < button (Directed by Chief of Bureau >. issistant in <• Editor, J. E. Rock^v Chief Clerk, James E. J CON'] I. NTS. t tacurrence i if tumors 5 I >tic 'ii li Experiments it Structure of tumors lit Relation of the tumors t>> other forms of disease II Effecl of the disease upon trees 12 -i mi i- to nurserymen, nursery inspectors, and orchardists 1"> 9ired "ii the distribution and severity of stem tumors or knots.... I (J [Cii 3 I I LIST RATIONS i - Fig. !. Stem tumors on an old apple tree at Mesilla Park, X. Mex (j 2. si cm inn Kirs cm a Meech quince tree at < Ihico, ( !al 7 ;;. Young tumors forming at the base of twigs on a Charlamori apple tree at Fayetteville, Ark 8 l. Older tumors than those shown in figi . 3 on a < harlamoff apple tree at Fayetteville, Ark it 5. Knots produced from a tumor on a cutting taken from a Charlamoff apple tree ami kept in moisl soil 1(1 6. Knots produced from tumors on a cutting taken from a Meech quince t ree near Chico, Cal It* 7. Longitudinal section of a tumor on an apple limb after throwing out roots when placed in soil 11 8. Longitudinal section of woolly-knot on a root-grafted apple tree grown from apparently healthy scion and root 11 9. The woolly-knot form of hairy-root on a Northern Spy apple tree grown in an experiment 1- 10. The simple form of hairy-root on an apple seedling grown in an experiment L3 1 1. The origin of hairy-root from buds on an apple seedling L3 [Cir. :: I 4 B. P. I :!'• SOME STEM TUMORS OR KNOTS ON All AND OUINCE TREES. OCCURRENCE OF TUMORS. A peculiar form of tumors or knots has been observed by the writer during the past five years occurring on the trunks, limbs, and twigs of apple trees (fig. !) and quince trees (fig. 2) in a number of local- ities in various portions of the United States. These localities arc in some cases widely separated, indicating that the disease may be found occurring over a wide extent of territory. The t ■- on the quince have been observed at Chico and other points in California, and re- ports of their occurrence, with specimens, have been received by the writer from Ansted, W. Va. Those on the apple have been noted in :i number of localities in California. Oregon, New Mexico. Texas, Arkansas, Kansas, Nebraska, Iowa, Missouri, Ellinois, and West Virginia. Specimens taken from apple seedling trees have been received from Mr. C. <>. Woodbury, of the Indiana Agricultural Experiment Station, collected in southern Indiana. Garcia, of the New Mexico Experiment Stat ion. reports the disease on apple trees from Mesilla Park, Hatch, and Garfield, X. Mex. Garman, of the Kentucky Experi m Station, has described a form is paper records the results of observations and experiments on a type of disease thai occurs in the apple and quince orchards and is particularly troublesome to nurserymen. The tumors described are related to hairy-root and crown-gall, and this publication summarizes a part of an extensive inves- tigation which Doctor Hedgcock is pursuing on the crown-gall and related dis- eases. The paper brings oul some importanl facts regarding the relation of the knots above ground to certain forms of hairy-root, and contains advice to nurserymen .-is to how to avoid the trouble. These investigations were begun at the Mississippi Valley Laboratory, St. Louis, Mo., under the direction of Doc- tor Hermann von Schrenk, and will I"- continued under the direct! r Mr. M. B. VTaite, Pathologist in Charge of investigations of Diseases of Fruits. B. T. Galloway, Pathologist and Physiologist, and Chief of Bureau. Garman, II. Diseases of Nursery Stock A Knot Disease of Apple Trees. Keuiu.k\ Agricultural Experlnieul Station, Bulletin 03, pp. 106-107 and flg. 4, L901. I : 3] 5 6 SOME STEM TUMORS OR KNOTS ON APPLE AND QUINCE TREES. of knots occurring on apple trees which is apparently the same disease; this he reports from at least two localities in the State. ' l^MM ^^_ 1 ti M^^^H ■B . 4$ j imL- j - ^^^'41 \Sk** :% -^ f ; y& KJr^tn Bpr vjl hrJH 1 jr Ik »% I 1 " ■|^ *^¥ : (Br 9K^ • i - [ ^ 9 IP I V*Jr££>Sfl L>jj f Pjjjjj Fig. 1 — stem tumors on ;m old apple tree at Mesilla Park, N. Mex. Waite, of the Bureau of Plant Industry, reports the disease as com- mon on the apple in tidewater Maryland and Virginia. DESCRIPTION. On the apple tree this disease appears most often oil the trunk and larger limbs (fig. 1), but in a number of instances it has been found [Cir.3] SOME STEM TUMORS OR KNOTS ON VPPL1 VND QUINCE FREES affecting the twigs and smaller 1 iml >~ (fig. 3), A g I example of the disease as found on all parts of the tr< ccurs on a Charlamoff apple tree in the experimental orchard <>f the Arkansas Agricultural Experiment Station, Fayetteville, Ark. This was first reported to the Bureau of Plant Industry by Vincenheller, of that station, who kindly donated the tree to the Department of A.griculture for further Fig. - Stem tumors on a Meech quince tree al Cuico, <':ii study. The progress of the disease on this tree has been noted for three successn e years. The tumors on this tree arc exceptionally large at the beginning, and frequently appear in the form <>l' a smooth swelling surrounding the base of a dormanl bud (fig. 3), quite often the terminal bud of [Clr. 3] 8 SOME STEM TUMORS OR KNOTS ON APPLE AND QUINCE TREES. a twig, and may be noted at the end of the growing season. In the form usually occurring on many other trees, the swellings appear on twigs and limbs indiscriminately, apparently having no connec- tion with the formation of buds. The tumors vary greatly in size on the same and on different trees; some are as small as a pea: others attain a size of 2 to 3 inches in diameter. This variation in size is noted even at the beginning of the formation. Imma- ture tumors are often formed on all por- tions of the tree, quite frequently occurring at the base of twigs (fig. ?>) or springing from older limbs or from the trunk. Dur- ing the first period of their growth the swellings are covered with a thick, fleshy layer of meristem and bark tissues. The growth for the first year or two i- often very rapid. At the end of a varying period of time, usually one to three year-, depend- ing on the variety of the tree and the condi- tions of growth in the locality where it i- found. the bark covering the tumors be- comes ruptured by the rapid formation in the interior of a very peculiar structure; the bark tissue ceases to grow, hut the inte- rior tissues develop a structure similar to that found in root formation in the hairy- root disease. As the bark breaks away, small elevations, -which resemble short thickened root caps, appear on the surface of the tumors, giving them a very warty ap- pearance (fig. 4). The knots now resemble I he origin of the formation of the woolly- knot form of hairy-root described by the writer" in a lecture to the National Nursery- men's Association last year. The tumors in their older form in some cases become hollowed out by a slight decay of the tissue in the center, which results either directly from the disease or from the entrance of wood-rotting organisms which are foreign to it. The mature form of these knots ( lie;. 1) resembles greatly the outgrowths upon the limbs of a num- ber of kinds of trees described by Sorauer 6 in Germany under the ■- FlG. '■'>. — Young tumors form- ing at the base of twigs on a Charlamoff apple tree al Fayetteville, Ark. <*Hedgcock, George <;. Prevention of „ Apple Crown-Gall and Hairy-Root. National Nurseryman, vol. 15, pp. 192-193, 1907. American Fruits, vol. T. p. 69, 1907. Apple Specialist, vol. I. pp. II 15, 1907. 6 Sorauer, r. Kropfmaser. Handbucb der Pflanzenkrankheiten, vol. 1. pp. 7::i t::i ami fig. :;s, 1886. [Cir. 3] SOME STEW rUMORS OR KNOTS OK U'IM.l IXD QUINC1 I 9 name of Kropfmaser, with which form of disease they may be identical. A similar form on Pirns mains chinensis has been de scribed by Kissa. On the quince tree the disease originates quite similarly to thai already described on the apple tree, with the exception that tumors not been noted affecting the end and base of small twigs. The disease appears first in the form of small swellings on various por- tions of the limbs and twigs of the trees. In a year or two the fleshy bark of these is broken open by the formation of num< root like structures, and the tumors assume a Mack, roughened ap- pearance, but resemble greatly in strucl ure the older forms described on the apple tree. These peculiar outgrowths (fig. 2) are often ren numerous on the limbs and trunks ot' quince trees. EXPERIMENTS. A number of limit- diseased simi- larly to those shown in figure 2 wer< taken from quince trees at Chico, Cal., and others similar to those shown in figures 1. 3, and 1 were taken from an apple tree at Fayetteville, Ark., and entirely cov- ered with moist soil at the Mis souri Botanical Garden, St. Louis, Mu.. during the month of March, 1906. A fter these had been covered with moist soil for about four week- they were taken out, and a number of the tumors had pro- duced root- in abundance from the surface (figs. ■'• and 6), bul no roots were thrown out from any other portion of the limbs. In the case of the apple limbs each of these knots, after the} had developed roots from I to 2 inches in length from further growth in the soil, agreed in appearance and structure with the knot- occurring in connection with one form of the hairy- root disease of the apple, known as the woolly-knot form (see fig. 9). In February, 1907, -cum- were taken from the Charlamoff tree pre- vioush mentioned, some of which contained knot- or tumor- like those Fig. I. Older tumors than those shown in figure ■". on a Charlamoff apple tree lyetteville, Ark. Kissa, V w. Kropfmaserbildung bei Ptrus malus ehinei fii i- Pilanz ?nkrankhelten, vol. 10, pp. 129 132 and 2 plates, 1900. [Clr. Z] Zeltschrift 10 SOME STEM TUMORS OR KNOTS ON APPLE AND QUINCE TREES. shown in figure '■'>. while others were smooth and apparently healthy. About 70 per cent contained no knots or tumors; these were grafted on piece roots from healthy apple seedlings. One hundred of these grafts were planted and grown on the Potomac Flats, near Washing- ton, D. C. The trees grown from these were dug at the end of the season, and 69.3 per cent were found to be diseased to a greater or Pig. 5. — Roots produced from a tumor on a cutting taken from a Charlamoff apple tree and kept in moist soil. Fig. 6. — Roots produced from tu- mors on a cutting taken from a Meech quince tree near Chico, Cal. less degree with the woolly-knot form of the hairy-root disease. The remaining trees were apparently healthy, having smooth roots. Those scions which had tumors before planting developed in nearly every instance root- from the tumors, which then agreed in structure and appearance with the woolly-knot form of hairy-root. STRUCTURE OF TUMORS. If a section is made longitudinally through one of the tumors taken from the limb of an apple tree after root- have been forced from it by moisture (fig. 7) and through one of the underground rooted tumors of the woolly-knot form of hairy-root (fig. 8), an identical structure is revealed. The wood elements of both are much distorted and disarranged, growing somewhat in a fan shape from the origin of the tumor- near the center of the stem or root. The [Cir.3] SOME STEM M MORS OB KNOTS ON \1TI.I I.ND QUINCE TREES. 11 bundle- nf wood) tissue are mingled abnormally with small patches of parenchymatous tissue. Springing from the surface of each of [ W-:*>m " : -/ : l> r 4— > M ^ngjgic^S* ^ -s^^^^A V JlXl^v/)u£ \ ^sj I' x Jw/^t/ V Fig. 7. Longitudinal section of a tumor on an apple limb after throwing out roots when placed in soil. s . —Longitudinal section of vvoolly-knol on a root-grafted apple tree grown from apparently healthy sciuu and c these forms are numerous fleshy roots which are often fasciated and distorted. These fleshy roots as they grow older either rot away in part or become \\ oody. RELATION OF THE TUMORS TO OTHER FORMS OF DISEASE. With our present knowledge, therefore, and as a result of the ob- servations and experiments previously mentioned, these tumors on the limbs and trunk- of apple trees may be considered the same disease as the woolly-knot U»\w (fig. 9) of hairy root; in other word-, they are the aerial form of hairy-root. The simple form of hairy-root, which was described first by Stewart, Rolfs, and Hall" and men- tioned later by the writer as a form of disease distinctly differenl "Stewart, 1\ •'.. Rolfs, I". M., and Hall, F. 11. Geneva, V v.. Agricultural Experiment Station Bulletin 191, pp. 300 301 and pi. ■_'. 1900; also Geneva, V 5 .. Agricultural Experinienl Station Report lit. pp. IT*', its and pi. 2','.. 1901. '■ Hedgcock, George <;. The Crown-Gall and Hairy [tool Diseases of the Ap pie Tree. Bureau of Plant Industry Bulletin No. 90, Pari [I, pi. •_'. fig. I, and pi. 3, lii:. 2, 1905. i i .3 | 12 SOME STEM TUMORS OR KNOTS ON APPLE AND QUINCE TREES. from crown-gall, is in the opinion of the writer only a form of the same disease as woolly-knot and these aerial tumor-. The simple form of hairy-root occurs most frequently upon seedling trees: it is present both on the stem and root portions of the trees. It consists, when it occurs on the roots, of numerous fine roots growing at right angles from the main roots or the taproot (fig. 10). These side roots arc very soft and succulent at first. but later harden and have a wiry appearance and texture. On the roots they arc usually quite uni- formly distributed in definite belts. Where this form occurs on shoots it springs more fre- quently from the vicinity of a bud (fig. 11), often just beneath it. These fine roots are formed in groups, or bunches, a great many often springing from a single origin. The origin of each of these clumps of roots is similar to that of the rudimentary roots in the aerial tumors. It follows, then, that the hairy-root disease may have at least three forms, which are more or less distinct: The simple, the woolly-knot, and the aerial forms. EFFECT OF THE DISEASE UPON TREES. Owing to the complexity in the forms of the hairy-root disease and the difficulty of obtaining accurate information as to their final effed upon orchard trees, and in view of the fact that extensive ex- periments are being conducted to determine the nature of each form and its effect upon the life and fruit fulness of apple trees, it will not he safe at present to make a definite statement as to the effect of these tumors further than to give the observations of the writer. ICir. 3] Fig. 9. -The woolly-knot form of hairy-root on a Northern Spy apple tree grown in an experiment. SOME STEM CUMORS OR KNOTS ON UM'l.i i.ND QUINCE TREES. l',\ A.pple trees from fifteen to twenty year- old badly diseased with these tumors have been observed in various localities in the Missis sippi Valley. The cores of the tumors ex- tended nearh to the hearl or center of the wood of the largest limbs, indicating that the tumors had been present during the life- time of the trees. Upon inquiry, the owners claimed that such trees usually bore as well as other trees in the orchard, and from all indi- cations tln\ were making a- good growth as other i iv,-. Tin' knots were apparently sound throughout, and a- far a- could be observed did no damage to the tree other than to ob- struct tli«' circulation to some extent. This interference with the circulation of the tree, however, can not be considered beneficial I • it- grow th. Waite, of the Bureau of Plant Industry, ha- observed in many instances thai the ecu ters of old tumor- on mature apple tree ten decay, either di- rectly as a resull of tin- disease or through the entrance id' organ- isms which may seriously injure the tree. The climate and condition- of the Atlantic coast, where Waite made hi- observations, are different from those in which the writer's observations were made, and this may ac- count in some measure for the different ef feet observed. A Study of the effects of the forms of the disease occurring on the root- of the apple tree is in progress and it is hoped that the results may l>e published later. Some of these results are very peculiar; for instance, the writer was surprised to find, in planting out in ■'" ; n ''''"' origin of an orchard under the same condition- during halry-rool from buds mi an , , _ . appi, dung, ;> very dry season about . « m » apple tree-, one hall of which had root- diseased with hair\ font of tl„. woolly-knol type (fig. 9) and the other half healthy. smooth root-, that a greater -land of trees was obtained with the for mer. The loss in the case of the hair\ pool trees was aboul 19 per cent, [Clr. 3] Fig. 10. The simple form of hairy roo t mi a a a pp I e sei dling grown in an ex- periment. 14 SOME STEM TUMORS OE KNOTS ON APPLE AND QUINCE TREES. and of the trees with smooth roots about :'>•_! per cent. This may be accounted for in part by the increased tendency to throw out roots in the case of the trees diseased with hairy-root. This peculiar behavior on the part of trees diseased with hairy- root is further explained by another experiment. Since apple trees are propagated commercially by grafting and budding, never by cuttings, because they root so rarely, it was a surprise to find that cuttings from trees with hairy-root are often able to throw out roots readily. In an experiment where 100 cuttings were taken from the shoots of yearling seedlings badly diseased with the simple form of hairy-root (fig. 10) and planted in moist soil in the greenhouse in early spring, more than 50 per cent rooted readily and 25 per cent grew into trees. On the other hand, out of 100 cuttings taken from healthy seedlings of the same lot, only 5 per cent rooted, and even then so feebly that none of them grew into trees. This experiment was carried out on an ordinary greenhouse bench with 8 inches of soil, without bottom heat. Some of the diseased quince trees observed by the writer in Cali- fornia were much stunted in their growth, but were considered a profitable investment by the owner on account of the crops of fruit which they had borne for several years. The quince trees in Cali- fornia appear to be quite universally affected with this disease, though usually with only a mild form. Xo indication has been found that the disease spreads in the orchard from one tree to another, either in the case of apple or quince trees, and experiments in which inoculations were made with chips from living tumors indicate that it is either very little or not at all contagious. In the case of apple trees, the percentage of disease on the roots of trees in nursery rows increases perceptibly from the first to the second year and remains i he same or decreases from the second to the third year. This observa- tion is based upon an extensive experiment. It might easily be true that a reasonable amount of this disease on a tree stimulates it and encourage- fruit production. That it does stimulate root production and may temporarily stimulate the growth of the tree are facts now well known to the writer and have been ob- served in many instances in the case of nursery trees. The disease, therefore, appears to be not as injurious as one would think. It can hardly be possible, however, that in the long run trees seriously affected by this disease will not sutler. Branches badly affected, as shown in figures 1 and '_!, certainly must have their movement of sap greatly impeded, their general activities much curtailed, and eventually their life shortened. It is not believed, however, that small tufts of hairy-roots on very limited areas of the root system of an apple tree will in any way perceptibly affect the growth and fruit- fulness of an apple tree or decrease its length of life, rcir. ::j SOME STEM rUMORS OR KNOTS ON iPPLE AND QUINCE FREES. L5 SUGGESTIONS TO NURSERYMEN, NURSERY INSPECTORS. AND ORCHARDISTS. Nurserymen are ad\ ised to be careful in the selection of scions and stocks for propagation and to see thai they are always taken from health} trees. The experiments of the writer in the case of 1 1 1 * - apple indicate that all forms of hairy-rool on scions increase where the scions arc taken from diseased trees. The following suggestions based upon experiments and observa bions arc made to nursery inspectors: Apple or quince trees badly diseased with any of the forms of hairy-root, whether aerial, woolly- knot, or simple, should be discarded as unfit for planting. Figures 1. ■_'. 3, l. '•'. and LO represent severe tj 7 pes of aerial, woolly-knot, and simple forms of hairy-root. The last two forms occur on the root- of trees in the nursery, while the first is found as a rule only on orchard trees, probably as a later development of the more intense forms of the disease on the root s. [f all trees affected with traces or milder forms of the disease as it occurs on the roots were discarded, it would mean the rejection of nearly all of the tree- grown in some localities. Such trees when they have a vigorous root system, notwithstanding trace- or mild forms of the disease, apparently grow as well a- healthy trees with smooth roots, or in some cases may grow better for the first few year-, so far as ha- I n ascertained l>\ experiments and observations. Until it can he shown that the piv-ciicc of the milder form- of the disease on the root - of nursery tree- will lead to it- further spread in the orchard, or that such tree- arc unprofitable for planting, it doc- not seem justifia ble to condemn them. On the other hand, the writer is not ready to assert that they are equally as good for planting as trees with smooth loot-. There is a difference of opinion as to what constitutes a healthy root system; some would limit the application of the term " healthy v to tree- entirely free from fibrous root formation on the main rout-. The writer has observed that trees with a very fibrous root system are often the product of certain kinds of soil and arc apparently as healthy as tree- more nearly free from such roots. Such tree- are equally as good for planting as those with smooth root- and might easily be mi-taken for diseased tree- slightly affected with trace- of hairy root. Until it can be -how n that librou- root- arc inferior to -i th roots and that the milder forms of hair} root seriously affect orchard trees, the writer is not ready to recommend the destruction of such trees in the nursery, since this course would probably involve an unnecessary loss of many thousands of dollars to the nurserymen and a consequent increase in the price of trees to the orchardists. [Clr. 3] 16 SOME STEM TUMORS OK KNOTS ON APPLE AND QUINCE TREES. ' Reports have been received from a number of localities where all the trees in orchards affected by these tumors ( fig. 1) have been cut down on account of their presence. In the absence of data proving the disease to be seriously injurious and in view of the writer's ob- servations, orchardists are advised for the present to allow such trees to remain in their orchards in cases where there is no apparent spread of the disease and where the trees are bearing profitable crops of fruit. If, on the other hand, the trees are not doing well as compared with healthy trees, it would be better to remove them. REPORTS DESIRED ON THE DISTRIBUTION AND SEVERITY OF STEM TUMORS OR KNOTS. It will readily he seen that further information as to the distribu- tion and severity of this disease is needed. To this end it is proposed to visit as many localities as possible where outbreaks of the disease are reported. All persons who have observed stem tumors or knots in orchards will confer a favor and will aid in accumulating data if they will report the localities where the disease occurs, with notes as to its severity. All communications should he addressed to the Bureau of Plant Industry. U. S. Department of Agriculture. Washington, D. C. Approved: mlllMMill James Wilson, Secretary oj Agriculture. 3 1262 08929 0042 Washington, D. C, April 1. 1908. [»'ir. 3] o