rkr"led VVilcox. OCT1OBER, 1903. BULLETIN No. 126. ALABA MA. Agricultural Experiment Station OF THE Alabama Polytechnic Institute. AUB URN. A LEAF-CURL DISEASE OF OAKS. .With 1 plate and 3. text-figures. E. MEAD WILCOX, Ph D. (Harvard). MONTGOMERY, ALA,. rHE BROWN PRINTING CO., PRINTERS AND 1903. BINI)ERS STATION COUNCIL. C. C. THACH........................................President. J. F. DUGGAR............................Director and Agriculturist. H. B. Ross...........................Chemist C. A. CARY.......................................Veterinarian. and State Chemist. E. M. WILCOX................Plant Physiologist and Pathologist. R. S MACKINTOSH....... .Horticulturist and State Horticulturist. J. T. ANDERSON.. Chemist in Charge of Soil and Crop Investigations. ASSISTANTS. C. L. HARE .............................. T. BRAGG First Assistant Chemist. Second Assistant Chemist. .............................. T. U. CULVER............................ Superintendent of Farm. W. L. THORNTON .................. J. M. JONES ............................. H. 0. SARGENT.................... Assistant in Veterinary Science. Assistant in Animal Industry. .. ........ Assistant in Horticulture. The Bulletins of this Station will be sent. free ,to any citizen of the State, on application to the Agricultural Experiment Station, Auburn, Alabama. r " b A LEAF-CURL DISEASE OF OAKS. BY B. MEAD WILCOX. Several of the native oaks are widely planted and highly prized in this State as shade trees both along city and town streets and about private dwellings. No small part of the beauty of a city or town is to be found in the number and character of the shade trees along its streets. While shade trees about private dwellings add much to the general appearance and attractiveness of the home and contribute largely to, the comfort and pleasure of the occupants of the house. In fact, the general condition of the shade trees along the streets of any town may well be taken as a fairly accurate index of the prosperity and intelligence of the people of the community. Many of our people now appreciate the value of good shade trees and are desirous of protecting them against all their enemnies. The purpose of the present bulletin is to call attention to one of the fungus diseases of some of our native oaks that threatens now to destroy many of these trees, particularly in our cities and towns. If, incidentally, more interest is aroused in home and city adornment through the agency of good shade trees, a useful purpose will have been accomplished in that direction. It is a pleasure to acknowledge here the kindness of numerous correspondents in this and other States who have sent the writer specimens and notes of great value. I wish also to give expression here to my indebtedness to Dr. N. L. Britton, Director-in-chief of the N. Y. Botanic Gardens, and members of his staff, and Miss Josephine A. Clark, Librarian of the U. S. Department of Agriculture, for many exceptional favors and helpful assistance rendered in the consultation of the extensive litearture in their charge. 172 NATIVE OAKS USEFUL AS SHADE TREES IN THIS STATE. The distribution over the state of the oaks that are most important for shade purposes in this state follows. Quotation marks enclose the_ statements made in Mohr's Plant Life of Alabama regarding the special habitat of The species are arranged alphabetieach of the cally by the scientific names. species. SCARLET OAK. Q aecrcas: coccinca Muench).-This known ' oak is frequent in the mountain region in "dry uplands, sandy and rocky soil." .well LAUREL OAK. (Quercus laurifolia Michx-. This species occurs over the southern half of the state but is most characteristic of the central pine belt and the coast plain. It occurs in "low rich woods." This is one of our most highly prized shade trees on account of its evergreen foliage. This oak is (9uercus nigra WAT'ER OAK. rather common from the Tennessee river valley south to the coast occurring naturally in."low rich woods and sandy pine-barren swamps." This tree is very widely planted as a shade tree in every part of the state. WILLOWXY OAK. (Quercus 1)hellos L - ThTis species is found front the 'rj'enInessee river valley southwTard the central pine belt of time state hut is not common in the southern half of the state. It occurs "in the bottom lands, borders of swamps. Most frequent in the, coves of damp soil." the Tennessee basin iu low woods of a This is also widely planted as a shade tree' and in some towns practically to. the exclusion of all other oaks. L. to cold' BLACK OAK OR QUERCIT'RON OAK. (Quercus the Tennessee occurs tvlutinta' Lam.) -This species from 173 river valley south to the upper portion of the coast pine belt. The bark is the so-called "quercitron bark" employed for tanning and as a dyestuff while the timber is of some value. LIVE OAK. (Quercus virginiana Mill. ) This oak occurs only in the coast plain district and rarely extends north of about 310. This, one of the valuable timber and tanning trees of the state, is at times in the coast plain counties a very important shade tree. SYMPTOMS OF THE DISEASE. The disease now under consideration makes its appearance early in the spring before the new leaves are mature. A number of grey or bluish spots appear on the leaf and the more rapid growth of the parenchyma of the leaf at these points renders the surface convex on one side and concave on the other. The concave side of this spot or area is: frequently on the upper side of the leaf but the spots on the same leaf may show variation in this regard. Somi trees have been seen in which the great, majority of the concavities were upon the lower surface but this is by no means the rule. These characteristic depressions, or "pockets," in the leaf result from the more rapid growth set up in that part of the leaf by the presence and action of the fungus causing the disease. These areas vary in diamnieter from 0.25 to 1 cm and are either isolated or confluent. In some of the narrow leaved oaks, such as Quercus phellos and laurifolia, it is not rare to find the spots confluent over so large a part of the whole leaf that the leaf is as badly curled as occurs in the peach leaf-curl, a closely related disease. The rapid spread of the disease from one leaf to another may lead to a partial or even complete defoliation 174 of the tree in early summer. However serious the outbreak of the disease and the resulting defoliation may be, the tree generally attempts by the formation of new leaves to compensate itself for the foliage lost. In extreme cases of defoliation it is not uncommon to see a tree with an entirely new foliage covering in midsummer. In most cases the second growth of leaves is not so badly injured by the disease as was the first and it may entirely escape the attacks of the disease. It is plain therefore from what has been said that the general effect of the disease upon the tree is much the same as defoliation due to any other cause. The effect of such a disease upon the life of the tree may best be appreciated when one recalls the fact that one of the most important functions of the leaves is to elaborate within their tissues the food material for use by the various parts of the plant in the building up of new tissues and other purposes. Even the roots are dependent upon the leaves for the food required for their growth and the defoliation of the tree may result in the most serious damage to the root system of the plant. Defoliation may result also in the great reduction of the growth in diameter of the stemn, and particularly in the reduction in the amount of reserve food material stored up in stems, roots and buds for the following year's growth. The second growth of leaves results from the proleptic developmeint of buds intended for the following year's growth. And since, as just stated, these buds have had stored in them less food than usual owing to the diseased condition of the foliage of the tree, it is natural that the second growth of leaves developing from them should not be so luxuriant as was the first leaf covering of the tree. Under such conditions, therefore, the tree enters upon the second year's growth with a very small supply of reserve food material. The cumulative effect of the disease may therefore result in many cases in the death of the tree from actual starvation. It is very rare 175 however that the most, severe attack of the disease will resuit in the death of the tree duringthe first year. FUNGUS CAUSING THE DISEASE. The fungus causing this disease is one of the lower Ascomn a group characterized by the formation.of its spores in small sacs of '"aci," singular "ascus." This fungus is very closely related to the Iwoascus deforman causing the well known leaf-curldisease'of ycetes, peaches. m Unlike the latter our fungus does not possess a perennial 'mycelium and. is carried over from one. year to 'another entirely through the agency of the ascospores. These germinate in the spring and, form a, mycelium that spreads out beneath the cuticle' of the leaves of the host to form there more or less extensive network of hyphw. From this vegetative, mycelium asci arise in large a numbers. These are-,more or less cy ndrical in form and are packed closely together side by side. See Fig. 1. the Fig. .- CGross section of a portion of a diseased leaf, showing the young. asci of the fungus. Each division of the scale is equivalent to 10 mu. 176 The asci arise between the epidermal cells and true cuticle and break through the cuticle toward maturity. Each ascus contains at maturity a large number of small spores though it is probable that in younger stages the typical condition is the 8-spored ascus. These'original 8 spores however multiply to a large extent within the cus resulting in the much larger number that be found in the Mature asci. The asci in the material have examined arefrwomi. 50 to 75 mu long and from 15 to 25, mu wide. The measured vary from 1.5 to 2.5 'mu in diameter. As has been mentioned in the discussion of syinptomoloy of the disease, the asci arise in small roundish ,areas upon the surface of the leaf. In the original.deof this fungus Desmazieres states that the spots arise on the lower surface of the leaf but this is We havenocertainy not uniformly the case. ticed that in Qucrcus velut'ina, the black oak, the spots are generally upon the lower surface only. The ame fact is recorded for this species by Robinson 1887. In 9 ercus 'nigra,the water oak, and someother species the spots occur on both the lower and upper surfaces of the leaves. In all the species examined these spots are at first rather definite bu't, sooner or later several, of the spots, fuse together so that the spore bearing areas became very in- the is to as- we spores the 'scription definite .and large. has Like many of the fungi the species, under consideration been referred to, under a rather large number of names in the past.. Desmazieres in 1848 published the Mont. & Desm. to include the sinnew genus gle new species Ascomyces coernlescen-s Mont. & Desm. But the genus Taph via had been established by Fries in 1815 who assigned to it but .onespecies, Taphria popuina, now known as Taphria aurea. Fries in 1825, however, complicated matters. by altering. his Asconzyces first 177 -published' name Taphria to Taphrina, to avoid, as he stated at thetime, confusion with Taphria a genus of insects.. Tulasnel in 1866 revised the genus Taphrina of FPries and made it include also the species of Exoascus. Robinson followed Tulasne and Johanson also in including all the species of the generaAscomyccs and Taphrina and Exoascas in the genus Taphrina, as extended by Tulasne. In my judgment the plan followed by Schroeter 1894) in taking up the original genus Taphria Fries is by far the best, and is in accord with present practices. assigns to this genus all thosespecies whose asci at maturity are multisporic and to the genus Exoascus Facrkciwi he assigns all those species whose uasci .at maturity are 8, or rarely 4, spored. In accordbe writ'ance with the above statements our species !tenTaphria coeralescens (Mont. & Desm.)Schroeter, and the following would be its synonmy Ascomyces coerulescens Mont. & Desm. 1848. Taphrina coerulescens (Mont. & Desm.) 1866. Schroeter shold Tulasne. Ascomyces quercus Cooke. 1878. Ascomyces alutaceus Von Thuemen. 1879. Exoascus coeruiscens (Mont. & Desm.,) beck. 1887. Taphria coerulescens (Mont. & Desm.) 1894. PREVENTION OF THE DISEASE. Sade- Schroeter, The fungus causing the disease now under consideration is an- annual and its myceliiu does, not perennate within the tissues: of the host as is .true of many of the closely related forms, such as the !peach. leaf-curl fun- gus. The treatment of such fungi, is very. much more readily-carried out than is the case with perennial- fungi, 178 a portion of whose mycelium lives over winter within the host plant, itself. In fact in the case of the particular fungus causing this disease no part of the mycelium enters the host plant farther than directly beneath the cuticle of the leaf. During the spring of 1902 an attempt was made to prevent, the appearance of the disease upon a specimen of the water oak, Q ercus nigra. The ordinary Bordeaux mixture was employed, made according to the following formula: Copper sulfat or "blue vitrol" .... 4 lbs. 4 lbs. JUnslaked lime ................ 50 gallons. Water ....................... Place the copper in a coarse cloth sack and dissolve it by suspending the sack in a wooden vessel holding about 115 gallons of water. Thel lime is then to be slaked with just enough water to ensure thorough slaking. The slaked lime is then to be made into a paste having the consistency of thick cream by adding water and stirring. When the solutions thus prepared are cold the lime water is to be poured into the copper sulfat solution through a fine sieve. Water is then to be added to make the solution up to the required 50 gallons and the whole thoroughly stirred before and while using. If too little lime has been employed the solution may injure tender foliage and the potassium ferryconaid test should be applied to determine this point. The test consists in adding to a small sample of the prepared mixture a few drops of a solution of potassium ferrocyanid made by adding one part by weight of the salt to five parts of watIf, upon the addition of a few drops oil this solution, er. the bordeaux mixture becomes a reddish-brown one may know that not enough lime has been employed in the preparation of the spraying solution. After the addition of more lime test again in the same manner and consider 179 the solution ready to use only when no discoloration appears after the addition of a few drops of the test solution to a small sample of the spraying mixture. The tree employed in our experiment was thoroughly sprayed about ten days before the buds opened and then at intervals of ten days three more sprayings were given. The dates were as follows: February 26, March 9, March 18, and March 26. Of course the first and all subsequent dates must be determined by the advancement of the season. Although the sprayed tree was in close proximity to unsprayed trees of the same species that were badly injured by the disease, the sprayed tree was only very slightly affected by the disease. More extensive experiments must be undertaken before one could say with any certainty that this line of treatment will in all cases he effectual in preventing the outbreak of this disease. But the one positive demonstration of the value of this treatment renders it very probable that the disease may be held in check by such treatment as that outlined above. It is expected that further experiments along this line will be undertaken during the coming spring with several species of oaks that are known to have had this disease during the present season. HOST INDEX OF THE FUNGUS. The fungus now under consideration has been reported as occurring on the following species of oaks in the states named. Quercus alba L. White Oak. Conn. N. J. Quercus brevifolia (Lam.) Sargent. Blue Jack. Ala. S. Car. Quercus coccinea Muench. N. J. Wisc. Quercus digitata (Marsh.) Sudworth. Spanish Oak. Ala. 180 Quercus laurifolia Michx. Laurel Oak. Fla. Quercus marylandica Muench. Black Jack. Ala. Quercus minor (Marsh.) Sargent. Ala. Quercus nigra L. Water Oak. Ala. Fla. Quercus pheltos L. Willow Oak. Ala. Fla. Qucrcus rabra L. Red, Oak. N. HI. N. Y. GEOGRAPHICAL DISTRIBUTION OF THE DISEASE. The Figure 2. distribution of this disease by states is shown in Fig. 2.-The disease described in' this Bulletin is known to be ent inthe states shaded. pres- disease there It is very likely that the particular fungus causing the indicated herein considered is found outside of the .-ares hut serious outbreaks of the disease are to be expected only in the gulf states. pear It would ap- that the climatic and other conditions. are in that region more favora1ble to the development of the fungus 181 than those prevailing to the north and west. Specimens of leaves showing the disease and the fungus herein described have been examined by the writer from'the following States: Alabama, California, Colorado, Connecti- cut, Florida, Georgia, Illinois, Louisiana, ,Massachusetts, Mississippi, New Hampshire, New Jersey, York, Rhode Island, South Carolina and Wisconsin. New Fig.P 3.--The disease, described in ent in the counties shaded. this Bulletin is known to be pres- 182 In figure 3 is shown the local distribution of the disease in this State counties so far as the writer has been able to examine material. The disease no doubt much damage in every county of the State hut particularly in the counties south of the Tennessee river valley. Material of the disease has been examined from the following counties : Autauga, Barbour, Bullock, Calhoun, Chilton,' Clarke, Coffee, Cullman, Lee, Mobile, Montgomery, Sumter and Tuscaloosa. 'by does Jefferson, OTHER SPECIES CLOSELY RELATED TO TAPHRIA COERULESCTIS. The following notes upon related species described as growing upon species of Qucrcas may be of interest. Ascomyces extensus Peck .1886. Reported on leaves of Quereus macrocarpa from New York state. kruchii Vuillemin. 1891. This species was found by Kruch. in Italy upon leaves of Quercus i-icis, and. is )y Schroeter referred to Taphria. Ascornyces quercus Cooke. 1878. This was reported by Cook in Rovenel's American Fungi upon leaves of Quercus cinera. It is identical appa-. rently with our Taphria cocrulescens. Ascornyces rubro-brunnusPeck. 1887. This was reported by Peck upon leaves of Quercus rubra. It is quite probable that all the above species belong in the genus Taphria but their specific standing we have not refer to the matdetermined with sufficient certainty ter in this connection. Eaoascuss to BIBLIOGRAPHY. following bibliography contains a list of the most articles consulted by the authori in important books The and the preparation of this bulletin. The titles are arranged 183 year of publicationprinted.dialphabetically with rectly beneath the name of the author. Atkinson, G. F. 1897 Some Fungi fron Alabama. Collected chiefly the during the years 1889-1892. Bull, page 13 Taphrina coerUniversity 3 :1-50. ulescens is reported from Alabama upon Quer- -the 'On of of Cornell cuas atica, cinerea, falcata obtusiloba, nigra and phellos. Cooke,M. C. 1878 Ravenel's American Fungi. Orevillea 6:129146. On page 142 is the original description (rAscotnyces quercus sp. n. This is reported from South Carolina upon leaves Quercus cinerea. Oook M. C. 1883 North American Fungi. Grevillea 11:106-ill. On page 106 are notes upon Ascornyces qacrcus Cooke. Desmazieres, J.-B. ll.-J. 1848 Dizieme notice sur les plantes cryptogames recemment decouvertes en France. Ann. Sci. Nat. Bot. lishes the new genus A scorn ges Mont. et Desm. 11110:342-361. On pages 345-346 he estab- to hold Ascoryces coeru'lescens Mont. et Desm. sp. n. Fries, -E. 1815 Observationes Mycologicee. 1:217. On the page gives the new genus Taphria Fr. and cited a single species under it, ie lists of Populus nigra, tremula populina" on and dilata ta. Fig 3 on plate 8 shows Taphria Fries but leaves "Taphria populina. Fries, E. 1825 System orbis vegetabilis. On page 317 he gives the generic namie Taphrina which he Nublsti Lutes 184 for the previously published name Taphri'. His reason for so doing is stated to be to avoid fusion with the genus of insects named Tapbria. con- Fries, E. 1829 Systema iycologicum. On pages 520-521 are notes on Tcphrina Fr. Fries, E. 1849 Summal vegetabilium scandinayhe seenci :eratio .ysstematica et criitica....2.:518. On the page cited is a description of Taphrina Fries with populina as the mentione1 species. L. 1.860 Euumcratio Fungorum Nassoyke. On page 29 he gives a description of the new genus e cies .Exoascus pruni, and gives a figure of the samespecies in figure 26 on plate 1. This establishes the genus Exoascus. Fuckel, L. 1869 Symbo-aie Myvcologicae. Beitraege zur Kenntniss der rheinischen. Pil ze. On page 252 he gives un- Taphrina first Fuckel, and der the genus Exoascus Fuckel )the. following species : prutni, def onnans and alni. Fuckel here states his preference for separating the mnulti spored species from the 8-spored, assigning the the former to the genus Ascornices and Taplhrina as done lat- ter. to the genus Exoascus; and his objection to the inclusion of both genera in the one genus by Tulasne in 1866. Ikeno, S. 1903 92 :1-31. Die, Sporenbildung von Taphrina-Arten. p1. 1-3. Flora fig. 1-2. Johanson, C. J. 1885 Om svaiupslaegtet T'aphrina och dithoerande svenska arter., Oefversigt af K. Vetensi. Akad.. 185 Forhandl. 1885 :29-47. p1. 1. Figrues of the following species are given: Taphrint borealis, carnc'a, nana, polyspora, Joteftillae and sadebeskii. Johanson, C. J. 1885 Studien uebler die Pilzgattung Taphrina. Bot. 'Central.bi. 33 :222-223, 251-256, The author reports Tapl-ina coeralescens in Sweden and Norway. Kru ch, 0. 1890 Sopra un caso di deformazione (Scopazzo) 'der rani deli' Elce1. Nota preliinare. Maipighia Record of Taphrina Quercas on 4 :424-430. ilicis in Italy. This, fungus was described as Exoascas Kruchii by Vuilleinin in 1891. Patterson, F. W. 1895 A study of North American parasitic Exoascaceoe. Bull. Lab. Nat,. list. State Univ. Iowa 33 :89-135. p1. 1-4. Peck, C. H. 1886 Report of the 'Botanist in 39th Report of the Regents of the University of N. Y. On page 50 he describes the new species tscwn yces extencas on Quecus macrocarpa. Fig. 1-3 on plate 1 284-287. represents this species which Peck staties is dis- tinct from Ascomyces quercas in "the character of the spote and also the spores." Peck, C. HI. 1887 Report of the Botanist in the 40th Report of of N\at. History* the New York State for the year 1886. On page 67 he gives a description of the new species Ascowtyces rubrobruarneus on Q. rubra. Meseum 186 IRobinson, B. L. 1887 Notes on the Genus Taphrina. Annals of Botany 1:163-176. Saccardo, P. A. 1880 Fungi dalmatici pauci ex herb. illustr.iR. de Visiani .additio uno -altierove mycete ex agliaet Michelia 2:150-153. On page 153 is a description of Ascrnyces alutaceus Thueml. upon.Quevua robor. Saccardo, P. A. 1898 Sylloge Fungoruln. 13..........Host list for the species of T'aphrina. Sadebeck, R. 1887 Die Pilze (Winter 12 :10. Sadebeck hereasthe genus Exoassigns Taphria coerulcsceens cus. Sa.debeck, R. 1893 Die parasitischeu Exoasceen. Eine Monographie. Jahrb. d. FHamb. Wiss. Anst. 102 :1-110. p1. 1-3. Sadebeck, 1895 Einige, neue Beobachtungen kritische Bemerkungen ueber die Exoasceae. Ber. Dent. bot. * Gesell. 13 :265-280. p1. 21. Cchroeter, J. *1894 Protodiscinee. Engler n. Pranti's Nat. Pflanzenfam. 11:157-161. fig. 136, HI. and J. Smith, W. G. 1894 Untersuchung der Morphologie und Anatomie pannonio,. to R. und der durch Exoiasceen verursachten Spross-und Blatt-Deformationen.. Forst. natural. Zeitschr. 3 :420-427, 433-465, 473-482. 1 plate and 18 text figures.Thuemen. F. von. 1879 Zwei nene blattbewohnende Flora von Wien. Verb. d. K. K. Ascomyceten der Zoool.-Bolt. Ge- 187 sell. Wien 29 :523-524. He describes as anew species Ascon yccs alutaceus on Quercus cens. e, L. B. Super Friesiano T'aphrinarum genee et. Ann.. Sci. Nat Bot. V-5 :222-136. He refers AS cornyces coerulescens of Mont. and Desm. t Taphrinacoerulescens. Tin, P. L'Exoascus Kruchii sp. nov. Rev. Mycol.' 13 " pube - ,'66 91 141-142. This species collected by Kruch iii Italy and its effect upon Quercus described was ilicis by him in 1890.