Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. j | ? ak SS : hy f ALF ie ES eee ee 4 ~an ei UNITED STATES DEPARTMENT OF AGRICULTURE = wr ertets DEPARTMENT BULLETIN No. 1186 Washington, D. C. A February 8, 1924 WHITE-PINE BLISTER RUST IN WESTERN EUROPE. By W. Sruart Morr, Assistant in White-Pine Blister-Rust Eradication, Office of Blister-Rust Control, Bureau of Plant Industry. CONTENTS. Page. Page. Batrrocnehnon= =) 4 ost a 1 | Control measures recommended in Scope of the investigations________ Pe | SAD WNT) OY Sea a a Se ne es, Se ALT. Rtorrenirevinws = 9) =e so Srl 3 | Significance of HKuropean experience Susceptibility of blister-rust hosts__ 3 CO PAIN ericare ss: = Ses Sa ee 21 Relation of white pines to European Economic aspects of the blister-rust FORESTRY 2 aS Ae aera 6 LOD eins Aeiere se ee Pee 2 25 Importance of currants and goose- Summary of the blister-rust situa- RING eee ee oe Se te Se 9 On Ouro pe = 255 sk 26 Damage to eastern white pine in European experience a warning to EEO ete Ss Se ES ata ACTIN CA eee ee a gs eee 28 miterature; Cited2222 2— Sa 29 INTRODUCTION. Following the outbreak of the white-pine blister rust in the north- eastern United States and in Ontario, Canada, foresters and patholo- gists sought a method of combat, and to this end European litera- ture was scanned for assistance (40). The European scientists who studied the causal fungus (Cronartium ribicola Fischer) had con- fined their research almost exclusively to its biology. Their inves- tigations as summarized in literature contain many suggestions for combating the disease, and they advance the principle of control by host separation but yield nothing definite on the practical applica- tion of control measures suited to American conditions. During the period from 1917 to 1921 the United States Department of Agricul- ture, in cooperation with the New England States, New York, Wis- consin, and Minnesota, conducted extensive experiments to develop methods of practical control of the disease under forest conditions. These experiments have fully demonstrated that under average forest conditions in the northeastern United States, white pine can 1 The serial numbers (italic) in parentheses refer to “ Literature cited” at the end of this bulletin. 55162°—24——-1 1 2 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. be effectively protected (10). Control is accomplished by uprooting | all wild and cultivated currant and gooseberry plants (Ribes) within a distance of 600 to 900 feet of the trees to be protected. ‘The de- struction of wild currant and gooseberry bushes can be accomplished at a cost sufficiently low to make it practicable and profitable to safe- guard the valuable white-pine crop of the Northeastern States. In the five years from 1918 to 1922 the cost of removing 19,224,118 wild currant and gooseberry bushes from 1,504,945 acres of forest and pasture land averaged 31.8 cents per acre. Any white-pine stand protected in this manner is safe from further rust infection for at least 5 to 10 years, and in many cases permanently, depending on whether or not local conditions are favorable or unfavorable to the growth of wild currant and gooseberry bushes. Several years of careful study are required to develop and perfect the cheapest and simplest methods of control, since many phases of this work are still in the experimental stage. Meanwhile, the control measures that have been developed should be generally applied at once to prevent further losses from this disease. The writer, a forester, observed the blister-rust situation in several European countries in 1919 and 1920 and takes this opportunity to acquaint others with his observations, which should be of especial interest to timberland owners on account of the rapid spread of the disease in the Northeastern States and its occurrence in British Columbia and Washington. Unless otherwise specified, the state- ments are based on the writer’s observations. It would have been quite impossible to conduct the work without the assistance and advice of scientists, departments of agriculture, and forest officials in the countries visited. The writer wishes to express his sincere appreciation to those who freely gave their time and efforts, which contributed so largely to the progress of this work. SCOPE OF THE INVESTIGATIONS. The primary purpose of this work was to gather information re- garding European methods of dealing with the white-pine blister rust which would assist in the control campaign in America. To accomplish this purpose, plantations of infected white pine were studied, foresters and pathologists interviewed, and data compiled as to the actual and financial loss caused by the disease. This work was supplemented by visiting the nurseries to observe their sanitary conditions, in order that a first-hand opinion might be formed as to the justification of the rigid quarantine regulations adopted by the United States against imported nursery stock. In addition, all available historical and biological data concerning the fungus were collected in Norway, Sweden, Denmark, Great Britain, France, and Belgium. ‘Typical specimens of ornamental white pine were seen very frequently in European parks and arboretums (Pl. I.). Even under the most favorable conditions they become prey for the blister rust. As the writer was in Sweden during the fall of 1919 and winter of 1919-20, work was begun in that country and extended to cover Norway and Denmark. By the middle of July the field was shifted to the British Isles, then to France and Belgium, which were com- pleted on N ovember 1, 1920. Miscellaneous notes were also gathered WHITE-PINE BLISTER RUST IN WESTERN EUROPE. eB) | by correspondence from other European countries, including Ger- many, Switzerland, Holland, and Russia, although these countries _were not actually visited. HISTORICAL REVIEW. Both the Peridermium and Cronartium forms of Cronartium vibicola have been known in Europe for 65 years. Dietrich first used the name about 1856 in a collection of dried plants entitled “Plantarum Florae Balticae Cryptogamarum” (//, p. 287), and European writers generally attribute the name to him. Five years later, in 1861, W. Saellen discovered the fungus on white pine. near Helsingfors, Finland. The form on Ribes, as far as is known, was not found in that country until 1897 (25, p. 447-449). Rostrup, in 1865, found the disease in Denmark on black currants, while Kor- nicke first found it in East Prussia in 1865 (27, p. 281). It was unknown in the rest of Germany until Fischer de Waldheim found it on Ribes aureum at Stralsund in 1871.2 The following year Magnus found it on the same species at Kiel (29). The disease was reported on one or both hosts from western Si- beria in 1879,? Sweden in 1880 (14), Norway in 1885 (7, p. 70), Holland in 1885 (32, p. 239), France in 1889,* and during the fol- lowing decades from the British Isles in 1892 (33), Belgium in 1894 (31), and Switzerland in 1895 (/5). The date 1887 is perhaps the most significant in blister-rust history, for in that year Klebahn separated the old composite species Peridermium pini Willd. into three species, namely, Peridermium pini ribicola Kleb., Peridermium cornui Rostrup and Klebahn, and Peridermiwm strobi Kleb. (23). In 1888 Klebahn determined by inoculation experiments the re- lationship between the Peridermium form on Pinus strobus and the Cronartium form on Ribes. The same year, in company with O. Nordstedt at Grimstorp, Westgotland, Sweden, this belief was veri- _ fied when they found white pine and black currants growing close _ together and both badly diseased (22). Following the determination of the host plants the fungus has been repeatedly found and reported from several European coun- _ tries, attracting the attention of both mycologists and foresters. Its distribution covers nearly the whole of western Europe and the British Isles and, according to statements by members of the Nor- wegian forest service, extends to 634° north latitude on the Nor- ° wegian coast. The date of the introduction of the blister rust into America is not known, but circumstantial evidence indicates that it was first introduced from Europe about 1898. SUSCEPTIBILITY OF BLISTER-RUST HOSTS. FIVE-NEEDLE PINES. The current European opinion is that the fungus originated on Pinus cembra in Siberia, migrated to Europe, and became far more virulent on the exotic five-leaved pines than on its supposed original host. Contrary to the writer’s expectations, he found no Pinus 2Rabenhorst, L. Fungi europaei exsicatti, No. 1595. ’ Thuemen, Felix von. Mycotheca universalis, No. 2049. *Specimen. Natural History Museum, Paris. 4 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. “pos ie lh ea cembra infected in the countries visited, although a single instance of its occurrence on this species is reported from Switzerland (37). Besides occurring on Pinus cembra and P. strobus, it has been found (and seen by the writer, except as otherwise noted) in Europe on other species as follows: P. ayacahuite Ehrenb. (British Isles and Belgium), P. excels (Denmark, 36, p. 312), P. flexilis (Belgium, France, Germany (42), Norway, Sweden), P. koraiensis (Sweden), | P. lambertiana (Belgium, British Isles, France, Germany (42)° | P. monticola (Belgium, British Isles, Germany (42)), P. pentaphylla (British Isles),° and P. peuce (Belgium,’ Germany (42)). Inoculation experiments successfully conducted by many European investigators show that all five-leaved pines and Ribes tested are susceptible to the fungus, though varying greatly in their degree of susceptibility. The experiments also prove the independence of the two forms Peridermium pint and P. strobi. It is worthy of mention at this point that the earliest known Cronartium on Ribes, though not C. ribicola, was collected by Jacquemont (43), the French ex- plorer, in India in 1830 and determined by Leveille as Cronartium asclepiadeum.® This is particularly significant, since in 1914 a bark- inhabiting Peridermium was found on the Himalayan white pine (Pinus excelsa) and sent to the Mycological Bureau at Pusa, India. Dr. E. J. Butler, of the Bureau of Mycology at Kew, England, kindly forwarded a specimen of the Peridermium to the writer, who sent it to Dr. R. H. Colley, of the Office of Forest Pathology, for deter, mination. He found it to be distinctly different from Cronartium ribicola. CURRANTS AND GOOSEBERRIES. Herbariums in the botanical museums were carefully scanned for Ribes species serving as hosts for Cronartium ribicola and for the localities and dates of occurrence. A total of 29 species was recorded, covering all the western European countries. Of the common Ribes, the most readily infected is ntgrum (41), while grossularia and rubrum are less susceptible. The writer found the first-mentioned species, but not the last-mentioned, infected in Europe. In the Vil- morin Arboretum at Nogent sur Vernisson, Loiret, France, 35 species were examined, and only two were found infected, namely, Ribes _ caucasicum and Ribes propinquum, both of which were badly dis- — eased. European foresters regard P7bes nigrum as the most danger- ous species and consider other European Ribes as of little consequence as agents for harboring the white-pine blister rust. CURRANTS AND GOOSEBERRIES KNOWN TO BE SUSCEPTIBLE. ; The list of varieties shown in Table 1 includes all infected species _ of Ribes seen by the writer in herbariums and elsewhere in Kurope,as _ well as those observed by a correspondent, Prof. O. Juel, in 1920, in — the Botanical Gardens at Upsala, Sweden; but undoubtedly other — host species exist in other European collections. 5 Correspondence with Professor Von Tubeuf, 6 Reported by the Forestry Commission for Scotland. 7 Reported as having occurred at Groenendael, Belgium. é 8 Specimen in Cryptogamic Herbarium, Botanical Museum, Paris. PLATE °I. Bul. 1186, U. S. Dept. of Agriculture. A CENTURY-OLD WHITE PINE IN BELGIUM. This magnificent specimen in the Domaine of St. Ode, Luxembourg, is one of our finest American trees on foreign soii. Photographed by Prof. Charles Bommer, Brussels, Belgium. Bul. 1186, U. S. Dept. of Agriculture. PLATE II. A GRoupP OF 70-YEAR-OLD WHITE PINES IN BELGIUM. Michel, near St. Hubert in the western Ardennes, in This tree would cut 1,400 board feet, valued in Europe at approximately $40 per thousand on the stump. Photographed by Prof. Charles Bommer, Brusscls, Belgium. The largest tree in this group, at the farm St. 1909 measured 110 feet in height, with a diameter of 33 inches at breast height. WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 5 TABLE 1.—List of species of Ribes infected with blister rust as seen by the writer in certain herbariums and elsewhere in EHurope and by Prof. O. Juel in the Botanical Gardens at Upsala, Sweden. [Names recorded from the specimen labels are shown in boldface type. The synonymy has been furnished by Dr. Frederick V. Coville, and the synonyms are here printed in SMALL CAPITALS. Doctor Coville believes that the gooseberries are more satisfac- torily regarded as belonging to Grossularia, a genus distinct from Ribes, which com- prises the currants. The species are_so treated in the revision of the family Gros- sulariaceew in the North American Flora (9). American species or varieties are designated by an asterisk (*). EHxrpianation of symbols.—Bru=—Botanical Museum, Brussels, Belgium; Chr=Botanical Museum, Christiania, Norway; Cop—Botanical Museum, Copenhagen, Denmark; Lon—British Museum, London, England; Sto=Royal Museum at Stockholm, Sweden (contains the herbariums of Rehms and Sydow, as well as those of Swedish collectors; Upsala—Botanical Gardens, Upsala, Sweden ; Vil=Vilmorin Arboretum, Nogent sur Vernisson, France. ] Name of species. Where seen. Remarks. Seen by the writer: - : 5 ; 3 albidum* L.......--- one ae en ee This presumably is Ribes albidum Paxton, which is an albino form of 2. glutinosum Benth. alpinwed Jo... 2... =. - Chirk Ons SbOn 2c. = 2 4 DpeMEICN NUM WI) eo oreo. ei. ....| See floridum. apiifolium........--- NEA OY GG Ope) 1 ae = ee ee According to Janezewski (22) this is a hort:- cultural variety of R. nigrum L. atropurpureum Mey ._... Se. Se ee ee According to Janczewski this is a variety of R. petraeum Wult. aureum* Pursh.....- Chr Cop sion, ‘Sto_-2- 2... This is probably R. odoratum Wendl., the com- : mon very sweet-scented golden currant of gardens which often passes under the name FR. aureum Pursh, a related species seldom cul- tivated and with little odor. See also ginkae- folium and tenuifiorum. caucasicum......-.- RG ee a eee ee Listed as holosericeum No. 7432 in Vilmorin’s “ catalogue. This is probably R. holosericeum Otto and Dietr., a hybrid of R. petraeum and R.rubrum. cynosbati* L........- ae Cea aes ee See gracile. DIACANTHA Pall....... Pe ae eae See Saxatile. floridum* L’Her..... gfofa sa Se ee oe eee The name R. floridum L’ Her., published in 1785, isasynonym of the much older R. americanum Mill., published in 1768. fontanesii* Colla..... Os SEOs ae ork 8 2 The name #. fontanesii Colla is a synonym of R. odoratum Wendl. ginkaefolium*......-)_._.. Ce eee Rae Ba cehs Sree This is presumably a form of R. aureum cata- logued for many years by Spaeth, a Berlin nurseryman, under the name f. aureum gink- | gifolium. Grrrmmontiai ee Fo) 2 cee. ak See albidum. gordonianum®* Lem.} Lon, Sto................-. This is a well-known hybrid between R. odoratum and FR. sanguineum. ; gracile* Michx.......- 2 esd Se Sas is eee ere Michaux’s F#. gracile is a smooth-fruited form of R. cynosbati L., but the plant that usually passes under the name Ff. gracile is R. mis- souriense Nutt., the Missouri gooseberry. grossularia L........ BrisCop-Lon; Sto. 25.2 -e - heterophyiirar Phi); |; lon, Sto: ..-.:.-<....---- According to Janczewski this is a variety of R. punctatum Ruiz. and Pav. POSE UICEPIMr OLLON |e 4. Soin e et Sse dee nim' See caucasicum. and Dietr. intermedium Tausch; Lon, Sto.......-...... .....| According to Dippel l. intermedium is a hybrid between FR. americanum and R. nigrum. longiracemosa Wil- |.......... Beers eee les Inoculated by Prof. W. Somerville, of Oxford. son. miacropotrys Pihw7 |) Lon, Sto:.. i. 22:2. 222: and Pav. menziesii* Pursh..... aes i Ne ofa eee een ae This is a well-known gooseberry of southern Oregon and northern California, but the name ; has often been misapplied to other Pacific coast species. See subvestitum. missouriense* Nutt. ..... QGs- sapere ea ee Wievuwe te. Bru, Chr, Cop, Lon, Sto...| See also apiifolium. niveum * Lindl.....-. MON SOs += a5a- 5 S22 Bolte : cru = ORO Ss fe ee ee See aureum and fontanesii. orientale Desf.......- ONS SUO4-tascen Sete Petes - oxyacanthoides* L.__|.._.. Os gS re ee sd parvifolia * Phio..... i eee GOS? tS eae cee This should be parvifolium Phil. petraeum Wulf....-. M@OP ss SLOr: = 22) + SA Es oN See also atropurpureum. PEpiagiytre Pure OV See ek Aceording to Janezewski this is R. warszewiczii } ancz. PUNCTATU Ms tuUliz, AMG) |e S22 .c258 op se-u- ses se) See heterophyllum. Pav. 6 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. TABLE 1.—List of species of Ribes infected with blister rust, etc.—Continued. : eee mec jl Name of species. | Where seen. | Remarks. Seen by the writer—Con. Facemos2- Wilson ie os ote eee ee eae | Inoculated by Prof. W. Somerville, of Oxford. LOtCUnGT OM wan |PLone Sto... = Michx. rubrum. L........-... Br, Cop. Sto. va... 46 5. Sanz uineung Purshel ons tO: 25. sets te ce saxatile Pall. 2s -2\te4.4 C022 4. eee ee | Thisis R. diacantha Pall. setosuml* Lindl2:: 2-|-42-: (6 ieee See ee ie © Subvestittum *..s22 230.2 GO i 38 i ef Bees sent ' The original PR. subvesiitum published by Hooker and Arnottis asynonym of R. menziesii Pursh., but other Pacific coast species of gooseberry have sometimes passed under the name of R. subvestitum. (SOUR ee ees 2 ee This is a synonym of R. aurewm Pursh. The name has sometimes been misapplied to R. gracillimum Coville and Britton. tenuifiorum Lindl.--| WARSZE WIGZI dan C7 sos \Ste tk Pie ae nce Sees See propinquum. Seen by Prof. O. Juel: ; americanum = Mall |>WUipsalae= 22 sso 8 aureum * Pursh..... ese COE toes Pes 2 cee ee biebersteinii Berl... .|.---. 04s See tae es Oe This is regarded by Janczewski as a variety of R. petraeum Wulf. divaricatum > Dousl.)\: dos.) = se ee divaricatum var. |-2... GO esi a Se | This is probably intended for divaricatum var. glabrifolium. glabrifiorum Koehne, a smooth-fiowered form | of R. divaricatum Dougl., a common northwest- coast gooseberry. : gordonianum* Lem.!.....- OG oe = it fee INERME Rydberg......|...-.. GO! ia). 4S ee eee | See oxyacanthoides nevadensis. multifiorum Kit.....|....- GOr 2 fate ee see ee Loi s4 bBo el Deen aa tisss2 G0 tSa=: -eera ees es orientale Desf_.-<=_..|.:--- GOs janis oet ee : oxyacanthoides|..... G0. ”: Sees a Ieee ~.| This is R. inerme Rydberg, the wine gooseberry. nevadensis.* PETRAEUM Wulf.......|..... GOs. Ree a a ee See biebersteinii. pinetorum * Greene_|...-- GO. oo et eee pubescens Swe... -|:2_-- dois Rave basse ee. oe This is doubtless R. rubrum pubescens Swartz. TUDE eS eee COS Ss 32954 = eee See also pubescens. sanguineum* Pursh_|..... G02. cS ee oe sylvestre Mert. and |..... COS eee ae ee This is asynonym of Fk. vulgare Lam. Koch. VULGARE Pam 42 |e GOSS Se re See sylvestre. RELATION OF WHITE PINES TO EUROPEAN FORESTRY. Kuropean forest conditions form a striking contrast to those in America. In Europe conservative methods of management and utilization have been in practice for centuries, whereas in America we are considering only the ways and means of applying such methods. Labor costs, though now abnormally high in Europe, as elsewhere, have usually been very low, a factor which has con- tributed largely to the success of forest practice abroad. With the development of forestry as a science, exotic tree species have been sought for study and experimental planting. There has been a continual search for species which would become readily naturalized and establish themselves under different conditions of planting and site. Trees from the New World were eagerly sought after, both for ornamental and forest planting. Many of the newcomers soon found a permanent place in the list of desirable species for use by the arboriculturist and the forester, foremost among which was Pinus strobus. In Europe the eastern white pine of North America (Pinus strobus) is invariably called ‘“ Weymouth pine.” According to Belon (8) this tree was growing in the royal nurseries at Fon- tainebleau, France, in 1553. If that is true, it is the earliest record of its appearance in Europe. It was not until after its introduc- WHITE-PINE BLISTER RUST IN WESTERN EUROPE. yi tion into England in 1705 and later into other European countries that the tree became prominent abroad. From the beginning its distinct and ornamental beauty interested foreigners (Pls. I and IT). Gold and silver medals were offered for plantations of Weymouth pine in England by the Society for the Encouragement of Arts in 1765 (17). This tree is now well known abroad and is one of the most widely distributed of introduced American species. Unfortunately in several countries Cronartium ribicola has taken such heavy toll that some foresters are wary of planting it, while others have abso- lutely discontinued its cultivation. White pine although widely distributed is not the commercially important forest tree in Europe that it is in America, for it is not a native species. The total area which it occupies is negligible in com- parison with the forested areas of European countries. The ease with which the wood can be worked and its varied uses for joinery, pattern making, matches, and in shipbuilding for masts, yards, and deals brought imported white pine into much demand abroad. Ac- cording to Laslatt, timber inspector of the British navy, when ships were built of wood “white pme served well for masts and bow- sprits,” but he says it was not strong enough for hght spars subject to great and sudden strain. For such requirements it was surpassed in strength and durability by Oregon fir (25, p. 356-366). To-day in Europe it is difficult to obtain white pine free from knots and sapwood. . In England the value of the best quality is advanced to 6s. ($1.50) per cubic foot. During the war the timber controller fixed the maximum price at 9s. 8d. per cubic foot, or approximately $389.75 per thousand board feet (20). Standing white pine has brought equally high prices. thoir weakenad tore broken of br thee, ee ee tion at Groenendael, the writer saw no cases where the suggested control methods have been adopted. Bommer emphasized the need of exterminating the fungus in the nurseries by destroying infected trees. Pechon in conversat:on with the writer placed little faith in the treatment with chemical solutions to check the development of the fungus and strongly advised the removal and burning of infected trees. Such a practice, however, is futile unless the currants and gooseberries in the locality are also destroyed. It is a common practice in many European nurseries to grow white- pine stock and Ribes near each other. After attention was called to 20 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. the blister-rust menace several of the nurseries of Belgium and France specializing in conifers for exportation discontinued the growing of black currants, since this species caused the most damage to pine. In other nurseries where the currants are of major im- portance the cultivation of five-leaved pines has been abandoned. The nursery beds shown in Figure 11 are in one of the largest of the French forest nurseries, situated near Orleans. These were started since the war and contain Austrian and Scotch pines, but no Ameri- can five-needle. pines, the growing of which was discontinued. BRITISH ISLES. British foresters declare the rust to be altogether too prevalent, but have made no efforts to control it. The fungus has raised more interest and concern among fruit growers than: it has among the foresters, because the former feared a decrease in their black- -cur- rant crop, entailing financial loss. Fic. 10.—A 17-year-old white-pine plantation near Epinal in the French - Vosges. Blister rust has attacked 52 per cent of the trees. his entire plantation is ex- posed to further infection from black-currant bushes growing 600 feet distant. It is doubtful whether merchantable timber will ever be obtained from it. Trials made at Oxford, England, to check the rust by spraying Ribes proved quite unsuccessful (2, p. 24). Reference to the spray- ing of young pines with a fungicide is made in the Quarterly Jour- nal of Forestry (5), witha statement that in a Belgian nursery seed- lings sprayed with a 1 per cent solution of potassium permanganate had been effectively protected. Chemically treating diseased parts of stem or limb may retard the development of the disease, but results thus far obtained are rather uncertain. Silvicultural methods will never control the fungus as long as Ribes bushes are permitted to grow in the neighborhood, but the opinion prevails that such methods may slightly decrease the amount of infection through better aera- tion and the entrance of more sunlight into the stand, especially if it occupies a moist site. If the black currants had been removed from the neighborhood of the plantation at Oxford, it would not be in its present poor condition (fig. 12). Control of a forest disease on as extensive a basis as the blister- rust work in the United States has no parallel in foreign forest prac- tice and presents a striking contrast to the limited measures of con- (Ee nee ieenash ee WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 21 trol which they have apphed to small groups or isolated ornamental specimens. Strenuous efforts to control the blister rust wherever it occurs are not made in Europe because the tree lacks the commercial status necessary to warrant such action. No European country has carried out a definite scheme of study for the control of Cronartium ribicola covering a number of years. The work done in the past has been conducted by individual initia- tive and interest, the investigators working independently and in some cases apparently unaware of each other’s activities. The work in Sweden by Eriksson was prompted by a popular fear lest the disease on Pinus strobus should prove a menace to the native Pznus sylvestris, the principal forest timber species. GERMANY. Klebahn’s work in Germany was undertaken from a purely sci- entific viewpoint. He paid little attention to the practical side of the question when he saw that the foresters were not concerned about it. When the United States restricted the entry of five-needle pine nursery stock in 1912 because of the fungus, the nursery- men took a greater in- terest in the subject. Large nurseries situ- ated near Halsten- beck, Germany, con- ducting an extensive export trade were par- ticularly affected by Fic. 11—A large forest-tree nursery in France. The seed : an v beds, started since the war, contain Austrian pine, Scotch this restriction. They pine, and Norway spruce. called upon Klebahn to witness that their stock was free from blister rust, which testimony he was bound to decline, since the fungus is difficult to detect on seed- lings. To Klebahn’s knowledge measures against the disease have not been taken anywhere in Germany, since Pinus strobus, aside from the nurserymen’s point of view, is of small economic im- portance. It is said that in the municipal forest of Heidelberg there are mature white-pine plantations covering nearly 150 acres. This is probably the largest single plantation of the species in Europe. Professor von Tubeuf, who has made a careful study of the blister rust in Germany, expects that in the future white pine will be grown less and less in that country.” : SIGNIFICANCE OF EUROPEAN EXPERIENCE TO AMERICA. The observations made abroad on the susceptibility of sugar pine, western white pine, and the limber pine show that these species are as readily attacked and as severely damaged by the white-pine blister rust as is the eastern white pine. Laurie found western white pine #2 Correspondence with Professor von Tubeuf, 1920, 22 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. fatally attacked at Murthly Castle, Scotland, in 1893, although no record of the occurrence was published until 1898 (26). The rust so badly damaged and disfigured the beautiful ornamental specimens Fic. 12.—Interior view of a white-pine plantation in Bagley Wood, near Oxford, Eng- land, in which 84 per cent of the trees are in a dead or dying condition. Every tree shown is diseased, and the tree in the foreground produced spores on October 15, 1920. Black currants were growing only 100 feet away. growing in the Murthly Castle Park, which had reached a height of 60 feet, that it was necessary to cut them down. To-day, only one tree remains of the original group of 50. This tree, having a diameter of 26 inches and a height of nearly 90 feet, is probably the ee WHITE-PINE BLISTER RUST IN WESTERN EUROPE. Te largest specimen of western white pine in the British Isles. It, too, is being killed by blister rust. In young plantations of western white pine at Balmoral Castle, Scotland, the blister rust is gradu- ally working with telling effect. Neger reports this species as being attacked by the rust in Germany (30, p. 280). The California sugar pine was found diseased in Scotland, France, and Belgium, and is reported from Germany.’® A most striking example of damage done to a single tree was observed at Murthly, Scotland. An arboretum specimen, 20 years old, with a height of 20 feet, is so heavily attacked on every limb to a height of 8 feet from the ground and so severely constricted on the stem that 1t is practically worthless. The late Sir Edmund Loder, of Horsham, Sussex, England, stated in correspondence that young sugar pines on his estate were attacked and killed by the rust. The appearance of infected trees in Belgium and France indicates that this species is highly susceptible. The limber pine was seen diseased in Norway, Sweden, and France, and Tubeuf states that it is infected in Germany (42). One of the most interesting cases of damage to the limber pine by the blister rust was seen at Softeland, near Bergen, Norway. In a plantation of {-year-old trees numbering 300, each tree was diseased and one- third of the number killed. The infection may be directly attributed to black-currant bushes growing in a garden 650 feet distant. At the Alnarp Forest nursery in Sweden 100 seedlings 6 years old were destroyed in 1920 because they were found to be diseased. A few younger seedlings remaining in the nursery (fig. 13) had de- veloped the disease in only two cases. In the National Arboretum at Nogent sur Vernisson, France, 12-year-old trees of this species have been killed by the disease (fig. 14). The Mexican white pine is heavily infected, the disease being found on this species in Belgium and England. Extensive planta- tions of these trees do not exist abroad, since they have been planted chiefly for ornamental purposes. The severity with which the fungus has attacked them and its rate of development clearly demon- strate that they are readily susceptible. These facts are of special significance to the United States and sound a clear call to action. The recent discovery of white-pine blister rust in British Columbia and Washington and the wide- spread abundance of wild currants and gooseberries in the Pacific coast and Rocky Mountain regions (there being about 60 species) place the valuable western five- “needle pines in an extremely hazard- ous position. Furthermore, climatic conditions of the West appear to be favorable to the spread and development of the fungus. There is a striking resemblance between the climate of western Nor- way, where the disease worked destructively in white pine and limber pine, and the northwest coast of the United States. Observations in Norway on the growth of the Douglas fir and Sitka spruce show that these indigenous species grow admirably in that region, thus giving evidence of the similarity of the climate of the west coast of Norway and of America. They give such promise of excellent volume production that in the future these trees will undoubtedly play an important role in the forestry practice of that country. 18 Correspondence with Professor von Tubeuf, 1920, 24 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. During the wet summer of 1917 (2, p. 24) the blister rust de- veloped so heavily and so seriously on cultivated black currants in England that nurserymen became alarmed and feared a decided setback to their currant crop because of defoliation of the bushes." A climatic cendition favorable to the spread of the rust on the currants results in an increased amount of pine infection. French Fic. 13.—Wimber pine (Pinus flexilis) growing in a nursery at Alnarp, Sweden. Blister rust first appeared here in 1920, at which time 100 seedlings 6 years old were de- stroyed. The young trees were growing within 300 feet of black currants and goose- berries. This shows the results that may be expected from an exposure of this species to the white-pine blister rust. foresters maintain that the disease is much more abundant during a wet year than in a dry one.* A _ similar opinion is upheld by members of the Belgian forest service. In the western United States the two factors of an abundance of wild currants and goose- berries and a climatic condition favorable to the fungus will work together to the detriment of the five-needle pines. European cli- ‘ 14 Notes obtained from Kew Garden Laboratory, through the courtesy of Dr. A, D. ‘otton. 18 Oral statement to the writer, ae Pangaea Be At re ety hae ee St hinias WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 25 matic conditions suitable to the growth of the five-needle pines were found favorable to the development of the blister rust. ECONOMIC ASPECTS OF THE BLISTER-RUST PROBLEM. The problem of controlling the blister rust in eastern North America is distinctly an economic one, and the practical application of forest pathology must aid in the protection of a basic industry by maintaining forest production. The task at present has developed beyond protecting merely a restricted area; it involves the entire country west as well as east. It has been positively demonstrated in eastern North Amer- ica that this disease can be controlled at a reasonable cost by up- rooting allcurrant and gooseberry bushes within 900 feet of white-pineforests. The blister rust can not be eradicated from North Amercia, but the local destruc- tion of currants and gooseberries prevents damage to pines within the control area. The value of the commercial eastern white pine alone amounts to $276,- 000,000 7 an asset well worth insuring against the rust. Re- cent careful studies made on the rate Fig. 14.—Limber pine (Pinus flevilis) in the National of rea h Arboretum at Nogent sur Vernisson, France, dying from =P = d of the a blister-rust attack. The 12-year-old tree in the center fungus in New York, was much weakened in 1920, as indicated by the yel- T : a lowing and shedding of the needles, and died the fol- New Hampshire, V er- lowing year. This species appears to be a ready victim mont, and Massachu- to the rust. setts show 15 per cent general infection. This is only the beginning of the invasion, for the disease is comparatively young here, having been only 25 years in the country and not imported to any appreciable extent until 1909. During the next decade it will gain impetus, spread with ever- increasing force, and impress its seriousness upon the public mind. The crux of the situation lies in the fact that the young white- pine growth which should become the commercial stands of the next 30 years will be severely hit. Clearly the control of the disease by the removal of currants and gooseberries in the East must be vigorously pursued. 16 Estimate of the United States Forest Service. 26 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. WESTERN NORTH AMERICA. One of the grave problems now confronting the Federal and State Governments is the safeguarding of the five-leaved pines of the West from this European pest. Now that the disease has made its appearance in British Columbia and Washington, what will be the result? The final outcome is difficult to forecast, but it is certain that the western five-leaved pine forests are in grave danger. Ob- servations made in Europe upon the susceptibility of sugar pine, western white pine, and limber pine to the fungus showed that these trees are as readily attacked and as severely damaged by the white-pine blister rust as is the eastern white pine. It means that 5228,400,000** worth of growing timber is to become the prey to a very insidious and dangerous disease. A widespread attack in this region is imminent and threatens to bring immeasur- able loss to private owners as well as to the Federal Government. To judge from the severity of the disease on these species of pines in Europe, it is no exaggeration to predict that the presence of the blister rust in the Northwest threatens the future position of these valuable pine species in the timber markets of the world. DECIDED STEPS OF ACTION NECESSARY. The action demanded by present conditions in order to contro] the blister rust is summarized as follows: (1) Energetic control of the disease in the East by the general eradication of currants and gooseberries in pine-growing sections. (2) Prompt and decisive action to control the disease in the West. (3) Eradication of the cultivated black currant, the most suscepti- ble alternate host of the blister rust and the most active agent in its spread and establishment. : (4) Strict adherence to and prosecution of the quarantine laws prohibiting the shipment of five-needle pines and currant and goose- berry plants from infected territory. Also the continued enforce- ment of the quarantine placing an absolute embargo on foreign nursery stock, thus preventing the entrance of the blister rust and other pests from foreign countries. Conditions demand such action. The scope of the problem is more than regional or national; it is international. Neither evasion of the quarantines nor laxity in the prosecution thereof can be permitted. The lability is large and the hazard great. SUMMARY OF THE BLISTER-RUST SITUATION IN EUROPE. The white-pine blister rust was first discovered some 65 years ago on pine and currants in the Baltic Provinces of Russia. Six years later it was seen to attack seriously 30-year-old white-pine trees in Finland and was marked as a dangerous tree disease. It is difficult to state where the disease originated, but the facts available to the writer indicate that Russia was the original home and Pinus cembra its host. From there it migrated and gradually spread over western Europe. Its occurrence was noted with increasing frequency from 1880 to 1900, particularly in those countries, such as the British Isles, Den- mark, Germany, and Sweden, in which plant pathology is carefully 17 Estimate of the United States Forest Service. t - uals ates heh tae. oa. area y WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 24 studied and in which tree species from America were being con- tinually sought for experimental forest planting and ornamental purposes. The first known occurrence of white pine in Europe was in the Royal Nurseries at Fontainebleau, France, in 1553. It was not exten- sively planted until after its fir st introduction into England in 1705 and later into other European countries. From the outset it gained the high regard of arboriculturists and foresters abroad because of its distinct ornamental beauty and the excellence and suitability of its wood for many purposes. To-day it is well known in Europe, having been one of the most widely distributed of the introduced American trees. Nurseries undertook the cultivation of white-pine stock for do- mestic sale and for export trade in localities where currant and gooseberry bushes were present, a practice which contributed largely to the spread of the fungus in Europe and America. As the de- mand for nursery stock increased, European nurseries, particularly those of Germany and France, undertook to meet the requirements. Until 1912 they could raise and ship white pines to America with- out restriction. This policy resulted in the importation of the white- pine blister rust into America about 1898, and this plague gradually spread through the northeastern white-pine region. Later, probably about 1910, it was introduced into British Columbia and has recently reached Washington. The spread of the blister rust followed the increase in the distri- bution of white pine in European countries, reaching even to the northernmost plantings of the species in Norway. Eastern white pine is not the only member of the American five-leaved pine group attacked by the blister rust. Other five-leaved pine species intro- duced into Europe for ornamental and experimental planting have hkewise become affected. Prominent among these are the California sugar pine, the western white pine, the limber pine, and the Mexican white pine. These species appear to be as readily susceptible as the eastern white pine. Cultivated black currants and gooseberries, especially black cur- rants, are very plentiful in European countries, and through them the disease is perpetuated with ever-increasing volume. Wild cur- rants and gooseberries are very limited as to the number of species, and the bushes are scarce in the forests. The control of blister rust as a forest-tree disease does not appear to have been seriously at- tempted abroad. A few efforts have been made to check the fungus on individual ornamental trees by removing the infected parts” or treating them with chemical solutions. The wholesale removal cf cultivated and wild currants and gooseberries is not practiced, not because of lack of knowledge of the damage done by the diseased currants, but because the currants are of more value to the people than the foreign white pine. The blister rust is gradually driving the white pine out of Europe. Unfortunately, the stands are gradually disappearing in Europe be- cause of damage by the blister rust. Foresters gener: ally are express- ing the opinion that the damage done by the fungus is too large to permit raising the species at a ‘profit. Often over 90 per cent of the trees in plantations are infected, and frequently one-third have been killed by the blister rust. Mature trees also are fatally attacked, as 28 BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. shown on eastern white pine in Sweden and France and western white pinein Scotland. Many European foresters have been enthusiastic over the future prospects of white pine in their countries, believing that it would come to occupy an important position in theirsystem of manage- ment and be regarded as an indigenous species. As shown by its growth abroad it has excellent volume ‘production, regenerates well (fie. 15), and is not exacting as to soil and moisture requirements. Such an optimistic outlook was held by foresters in Denmark, Belgium, and Norway, while the Germans had faith enough in the productive capacity of the species to plant considerable areas with white pine. Saat omelets SEB COR BEm if an € i? Fes ‘ E , Fad ii : EOP TI Prete: sale gest meyer tees nt eC A SR 88: pape 3 at ey gee Fic. 15.—Natural white-pine reproduction in the communal forest of La Mouche, Epinal, France. In this part of the forest 36 per cent of the young trees were attacked by the blister rust, thus greatly reducing the probability of a future crop. Other foreign conifers, such as Douglas fir, Sitka spruce, and Japanese larch, will gradually replace the disappearing white pine. Himalayan and Balkan pine will also come into more extensive use for forest planting. EUROPEAN EXPERIENCE A WARNING TO AMERICA. This disease is a most dangerous forest enemy. It readily kills mature trees, but the greatest menace is in sweeping out of existence the young pine stock of to-day which is to become the mature timber of to-morrow. Although it is slow in developing, it is nevertheless constant in action and certain in destruction, undermining the very security of our forest capital, without which continued forest pro- duction is impossible. Blister-rust control is a national problem. It is necessary to pro- tect a resource so essential as white pine for economic and industrial development. Simple and practical methods are available to any pine owner in the eastern United States which enable him to safe- guard his pines from this disease. The blister rust is spreading into the western white- -pine and sugar-pine forests and threatens the com- mercial extinction of these species. Vigorous action is required to de- velop and apply measures that will minimize the damage in the West. sone diem ad iis el (1) (2) (3) (4) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) al LITERATURE CITED. ANONYMOUS. 1765. An account of the premiums offered this year (1765) by the Society for the encouragement of arts, manufactures, and com- merce. For planting and husbandry. Jn Museum Rusticum et Commerciale, v. 4, p. 379-890. 1920. Report on the occurrence of insect and fungus pests on plants in England and Wales in the year 1918. Bd. Agr. & Fisheries [Gt. Brit.], Misc. Pub. 23, 65 p. AYRES, THOMAS. 2824. A description of a remarkably large gooseberry plant. In Trans. Hort. Soc. London, v. 5, p. 490-491. BALTz. 1919. Die Weymouthskiefer (Pinus strobus). Jn Forstw. Centbl., Jahrg. 63 (N. F. 41). p. 302-307. BEEvor, HucGH R. 1919. Young woods in Belgium. Jn Quart. Jour. Forestry, v. 13, p. . 272275. BELGIUM. CONSEIL SUPERIEUR DES FORETS. 1909. Rapport sur l’introduction des essences exotiques en Belgique. par le Comte Amédée Visart et Charles Bommer. 381 p., 6 pl. Bruxelles. Liste des ouvrages cités, p. 361-365. BLytTT, AXEL. 1896. Bidrag til kundskaben om Norges soparter. Forhandl. Vidensk. Selsk. Christiana, 1896, No. 6, 75 p. BoLie, CARL. 1890. Wann erscheint die Weymouthskiefer zuerst in Europa? In Gartenflora, Jahrg, 39, p. 434-488. CovILLE, FREDERICK VERNON, and BRITTON, NATHANIEL Lorp. 1908. Grossulariaceae. In North Amer. Flora, v. 22, p. 193-225. DETWILER, SAMUEL B. [1921.] White pine blister rust control, 1920. Jn Bul. 6, Amer. Plant Pest Committee, p. 1-6. DretTricH. HEINRICH AUGUST. 1859. Blicke in die Cryptogamenwelt der Ostseeprovinzen. Jn Arch. Naturk. Liv- Elst- und Kurlands, Ser. 2, Bd. 1, p. 261-416. ELwes, Henry JOHN, and HeNRy, AUGUSTINE. 1910. The trees of Great Britain & Ireland, v. 5,. p. 1001-1333, pl. 271-339. Edinburgh. ERIKSSON, JAKOB. 1890. Landtbruksbotanisk berattelse. 17 Blasrost 4 tall (Peridermium Pini (Willd.) -Wallr. och P. Strobi Kleb.) Jn Landtbr. Akad. [Sweden], Handl, och Tidskr., Arg. 29, p. 223-225. 1896. Nagra iakttagelser rG6rande blasrosten 4A tallstammar, dess natur och forekomstatt. Jn K. Landtbr. Akad. [Sweden]. Handl. och Tidskr. Arg. 35, p. 240-258, 3 fig. Bibliographical footnotes. FISCHER, EDUARD. 1898. Beitrige zur Kenntniss der schweizerischen Rostpilze. Jn Bul. Herb. Boissier, t. 6, p. 11-17. GoBLET d’ALVIELLA, FELIX. 1919. Eléments de sylviculture, v. 1, xiv, 383 p.. 86 fig. Paris, Bruxelles. Principaux ouvrages consultés, p. 371-872. 29 30 (17) (18) (35) (34) (35) (36) BULLETIN 1186, U. S. DEPARTMENT OF AGRICULTURE. Hanson, C. O. 1911. Forestry for woodmen. 222 p., 15 fig., 12 pl. Oxford. HISINGER, EDWARD. 1876. Peridermium pini (Willd.) Pers. a corticola, d6dande Pinus strobus. Jn Bot. Notiser, 1876, p. 75. Hooker, J. D. 1879. The flora of British India, v. 2, 792 p. London. Howarp, ALEXANDER L. 1920. A manual of the timbers of the world... xvi, 445 p., illus. London. JANCZEWSKI, EDUARD, RITTER VON GLINKA. 1907. Monographie des groseilliers, Ribes L. Jn Mém. Soc. Phys. et Hist. Nat. Genéve, t. 35, p. 199-517, illus. KLEBAHN, H. 1888. Uber den Rindenrost der Weymouthskiefer, Peridermium (Aecidium) Strobi. Jn Bot. Notiser, 1888, p. 229-230, 236. 1889. Beobachtungen und Streitfragen tiber die Blasenroste. In Abhandl. Naturw. Ver. Bremen, Bd. 10, p. 145-155, pl. 1. Bibli- ographical footnotes. LAMARCK, J. B. DE, and CANDOLLE, A. P. DE. 1815. Flore frangaise . .. Ed. 3, t. 4.,944 p. Paris. LASLETT, THOMAS. 1894. Timber and timber trees native and foreign. Ed. 2, com- pletely revised ...by H. Marshall Ward. xx, 442 p., 34 fig. London and New York. . LAURIE, JAMES. 1898. Diseased Pinus monticola. Jn Gard. Chron., ser. 3, v. 23, p. 244. LIND, JENS. 1913. Danish fungi as represented in the herbarium of E. Rostrup. 648 p., 42 fig., 9 pl. List of literature, p. 555-606. Liro, J. Ivar. 1908. Uredineae Fennicae, Findlands rostsvampar. Bidr. Kann. Fin- lands Natur och Folk, Hiftet 65, 642 p., 15 fig. Foérteckning 6fver den i arbetet citerade literaturen, p. 585-605. MAGNUS, PAUL. 1873. Mycologische Bemerkungen. Jn Hedwigia, Bd. 12, p. 49-53. NeEceEr, F. W. 1906. Kleinere mycologische Beobachtungen. Jn Ann. Mycol., Jahrg. 4, p. 279-287. [NIJPELS, PAUL.] 1900. La Peridermium du Weymouth. Jn Bul. Soc. Cent. Forest. Belg., v. 7, p. STT-579. OuUDEMANS, C. A. J. A. 1885. Aanwinsten voor de flora mycologica van Nederland. IX en X. In Nederland. Kruidkundig Archief, ser. 2, deel 4, p. 203-278, pl. 46. PLowRIGHT, C. B. 1892. Cronartium ribicola. In Gard, Chron., ser. 3, v. 12, p. 187, 501. POIRAULT, GEORGES. : 1890. Les Urédinées et leur plantes nourriciéres. Jn Jour. Bot. [Paris], t. 4, p. 229-234, 245-251, 307-315, 342-348. Rostrup, EMI. 1889. Afbildning og Beskrivelse af de farligste Snyltesvampe i Dan- marks Skove. 380 p., illus., 8 col. pl. Kgbenhavn. 1902. Plantepatologi. ... 640 p., 259 fig. Kgbenhavn, WHITE-PINE BLISTER RUST IN WESTERN EUROPE. 31 (87) SCHELLENBERG, H. C. 1904. Der Blasenrost der Arve. Jn Naturw, Ztschr. Land- u. Forstw., Jahrg. 2, p. 283-241, 2 fig. Bibliographical footnotes. (88) ScHLicH, WILLIAM. ; 1919. The Bagley Wood sample plots. Jn Quart. Jour. Forestry, v. 13, p. 266-268. (39) ScH¢@YEN, W. M. 1897. Beretning om Skadeinsekter og Plantesygdomme i 1896. 58 p., illus. (Report of State Entomologist, Norway.) (40) SPAULDING, PERLEY. 1911. The blister rust of white pine. U. S, Dept. Agr., Bur, Plant Indus. Bul. 206, 88 p., 5 fig., 2 pl. Bibliography, p. 61-78. (41) Taytor, MINNIE W. 1922. Potential sporidia production per unit in Cronartium ribicola. In Phytopathology, v. 12, p. 298-800, '1 fig. (42) TuBrEuF, CARL von. 1914, Neuere Versuche und Beobachtungen tiber den Blasenrost der Weymouthskiefer. Jn Naturw. Ztschr. Forst- u. Landw., Jahrg. 12, p. 484491. (43) TuLASNE, L. R. 1854. Second Mémoire sur les Urédinées et les Ustilaginées. Jn Ann. Sci. Nat. Bot., sér. 4, t. 2, p. 77-196, pl. 7-12. (44) WappEs, L. 1896. Zur Naturgeschichte der Weymouthskiefer. Jn Forstl. Naturw. Ztsehr., Jahrg. 5, p. 205-219, pl. 13-14. French translation, without plates, in Bul. Soc. Cent, Forest. Belg., v. 4, p. 105-123. 1897. HITE-PINE BLISTER RUST may destroy much of the white pine of the United States. This destructive dis- ease probably had its original home in Asia, later reaching Europe. It was introduced into America during the years 1898 to 1910. European and American investigations indi- cate that this rust can not spread direct from pine to pine and that an intermediate stage of development on currant and gooseberry bushes is necessary before it can harm the pine. Studies of the disease in this country showed that the dis- iance to which currant and gooseberry bushes infect pines is comparatively short. This knowledge is the basis of the local control work in the United States, which was begun experimentally in 1916. These experiments prove that un- der ordinary forest conditions in the eastern United States a stand of white pine is subject to little or no damage from the rust if there are no European black currants grow- ing within a mile and no other currant or gooseberry bushes within 900 feet. European black currants are dangerous to pine at greater distances than other species because they are more susceptible to the rust and produce a much larger volume of spores per unit of infected leaf surface. The purpose of the study in western Europe in 1919-20 was to determine how destructive the blister rust had been to American white-pine species planted abroad and what steps, if any, had been taken to combat this disease in for- eign countries that would be of practical value in control- ling the disease in the United States. It was found that cultivated black currants and gooseberries, especially black currants, are very abundant in Europe and popularly con- sidered of more value than the foreign white pine. Conse- quently these bushes have not been removed from the vicinity of the white-pine plantations, and the blister rust is sradually driving these trees out of Europe by destroying such a large percentage that it is unprofitable to cultivate the species. White pine is being supplanted by other for- eign conifers, such as Japanese larch, Douglas fir, Sitka spruce, and Balkan pine. Very recently the blister rust has been found on the Pacific coast in Washington and British Columbia. This discovery is a matter of great concern, since there are seven different white-pine species in the West and the coun- try’s greatest white-pine resources are centered in the western white-pine and sugar-pine forests. Western white pine and limber pine apparently are more susceptible to the blister rust than eastern white pine. Sugar pine is also highly susceptible. To delay the spread of the rust through the eradication of cultivated black currants and quarantine enforcement and the development of practical local control measures adapted to the conditions found in western forests are the only alternatives to the ultimate extinction of the most valuable commercial pine-timber species of the West. 39 WASHINGTON : GOVERNMENT PRINTING OFFICE : 1923