L TOBACCO DISEASES. U. TOBACCO BREEDING.

WOOSTER, OHIO, U. S. A., NOVEMBER, 1904,

BULLETIN 156._

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mi a 1 EXPERIMENT STATION, Wooster, Ohio.

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DA D:“WHITE; Presidents ss.c. <ccises ecastatert ole Ore tesa ncteeenete oo he ee pum Gastal ral Ok BS BRADEUTE; JS CCLELATY az foie sere ote Token sleie oe orev taal eee ele eae Xenia D2 Ls SAMBSON) * PreaSuPen oosies ssn cons aro oecetaravels bets eckeener one rere eee Cincinnati SAS UID RIG Kor ces teers cue oeimeumeary se iane gence = ey ete pees Meme Rr airs AeA RAS (ec t8 Mantua ATIVA AGER 665i ois'e 3 Sethe o aalesmnctits ms ibze uo vyaltye. ot = nanei@ ohora waneNeh st tes Tener ae eta eee Wooster

STATION STAFF.

CHARLES (Ei, MP HORNE, mle PAC acre yarcnsintreiie eee ener Ba RSE iS NO dias Bact Director MOA U UTE Ale (Ca IoDI oc pocbUbDo aomoDona6 oOo ues oO" He; culturist and Vice Director (Superintendent of Orchards, Garden: and Greenhouses. ) AUGUSTINE? D: (SEUBY,-B.oS Coro Sissi ne oe gait hes ae eer ee -..Botanist (In charge of botanical and plan physiological and pathological investigations. ) (Cra Cre, A WAC REGO cin tc otian ach Paty ahaceerels 8 ehh aan. Oe eee ieee Agriculturist

(Superinteident of Farm.) ry, TORN UW VAMES asus Colony ds as SS o-aile aaa alells ole sicheeloiarchs Resconic i Seen ees Chemist epetls GODDARD sear. fofer eroele ieee ete BS dcplombedeysie te Sa ene eters. oes ee eee Experimentalist He cAS GOSSARD; MES Sins co nem Saisie ohieie gt eters oe ater apeien Teenie lana Entomologist WTA SETS RRA MR S559. Gis walle ote estoy oh eile eb ide a ort eel aeRsy eel oe ns es oe anes area eas eacetisas Bursar CRAREN CES Win) WALD S Eris Comer nrreen sre erro ane nee eee Assistant Horticulturist (In charge of Greenhouses. ) Ideal als MSLOe HO oonanse bcoIOae ws teal BA cTauec heen se Seas EIeWe we Lt one onlone Assistant Horticulturist (In charge of Orchards. ) TSS. SHIOUSER Be 1S sais eres Ga a osiens ao merce ota te ete Assistant Entomologist JN VAN SEO OK AG NM ee tte heme cetera eeier arene Assistant Plant Pathologist YS AR WEL LONG doe We inieeceetd So eine ee eee eee Assistant Chemist Witira Mm TOG MES 22 ciwose sles se tverenl sole ero wo mye re leler el rete Teot reer poke eerie Farm Foreman CHARIPES PALE EVATERONictrstcietelsieicioietatseiee er ctenche loa neste rere Meteorological Observer CARY SWEET tic ctic a letecoitle ale Grasiecistans cieieile wualeleievelosevre rencterelomsie ole keke Rene Ke meaeRemene eee eae Mechanic IEA Dy) BY GF WARD INES Pin On AO UD OOO SOUS OMOOBUMOUOO NOC ARODOCOOOd eit ereeean Mailing Clerk MAR VSG OES ects toad. cia vert b ct ereraleus is setts eopyane vets the alone eietoke Memes ce eee Stenographer PU RIAUNUISoVVe tl Gr Soe teteget created folate creer colons aicteterele cee oh otcieretete le esi te otc at eae JEdrbauere EDWARD = NIOEINT toremmareleesiele eieremisiecleketers Supt. Northeastern Test-farm, Strongsville HENPY Mie WACHTER scscocc cece Supt. Southwestern Test-farm, Germantown IPAS A ISKCs COBO ABSA Scop odao oo Sonoda ak Supt. Southeastern Test-farm, Carpenter

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BULLETIN _ :

OF THE

Ohio Agricultural Experiment Station

NuMBER 126. NovrEmMBeEr, 1904.

-TOBACCO DISEASES AND TOBACCO BREEDING.

BYE AS 2 SHE BY.

I—TOBACCO DISEASES.

PRELIMINARY AND EXPERIMENTAL STUDIES OF MOSAIC DISEASE, ROOT ROT, BED ROT, BROOM RAPE AND CURING HOUSE TROUBLES IN OHIO.

INTRODUCTION.

The tobacco’ industry in Ohio, though apparently somewhat localized, has vital interest for the areas devoted to tobacco growing. The writer confesses a personal sympathy with tobacco growers by reason of early experience in the tobacco field. The recent es- tablishment at Germantown, Montgomery county, of a Station test farm upon which tobacco probiems are given especial consideration, brings Station officers into closer relations with the tobacco. in- dustry. Aside from such matters as arose from desultory cor- respondence, little attention has been given by the department in the past to the study of tobacco diseases. The present publica- tion is issued with the double purpose of presenting some matters of present value and of securing a closer study of tobacco maladies by the growers of this staple. We should be able, in time, to increase our present limited and fragmentary knowledge of the treubles of the tobacco plant bed, the tobacco field and of the curing

house. 87

88 OHIO EXPERIMENT STATION; BULLETIN 156. g pee 68

TOBACCO DISEASES CLASSIFIED. “| The tobacco plant, in common with many others, suffers from any lack of proper nutrition, and the diseases from this cause may Le varied. Wemay have unsatisfactory growth and maturity from lack of the 1:ineral plant foods or from lack of adequate mcisture. In the present discussion, however, we shall not attempt to cover this line of trou..'es; we confine ourselves rather to specific maladies which may affect particular plants without touching others living under like external conditions. Here a plant may have abnormal color variations in the leaves as by yellow though not dying areas in them, at the same time that the adjoining plants of the same variety and seed strain are normal in color and healthy in behavior. Or a plant may suddenly wilt ~own and fail to attain full recovery and yet another may suffer fron: dead spots in the leaves. All these abnormal features which impair the vigor, productiveness or health- fulness of such plants, we term diseases. We shall omit here the discussion of insect injuries, though these in a sense come under one of the divisions to be considered. The root rot and the wilt are parasitic diseases as we shall see later; they are caused by specific parasitic organisms. Non-parasitic diseases are such as have n0

specific parasitic organisms constantly associated with them.

I. NON-PARASITIC DISEASES OF TOBACCO. 1. THE MOSAIC DISEASE.

The mosaic disease, or ““Frenching’’, of tobacco, locally known in Connecticut as “‘calico,’”’ is one of unusual interest. ‘The diseased plants exhibit such a mottled appearance of the leaves, due to the alternating areas of darker green and yellowish green in them, as to make the appearance of the plants very striking. The leaves are veritable mosaics; as such they catch and hold the interest of the observer. Certain plants will exhibit these characteristics and color markings while others near them have the normal, uniform green color. Jn the tobacco field, as most will recall, plants with abnormal color are quite frequent in unfayorable soil situations and especially around wet areas. This class of situations is how- ever by no means the only one; no particular specifications may be made to apply generally in th’s respect. The mosaic disease oc- curs in practically ail tobacco areus of this state and of the United States and under favorable soil conditions; indeed the disease is general throughout the tobacco growing districts of Europe and Asia as well. Along with the mottled, or mosaic z_ pearance of the leaves we may have distortions of the leaves ave to the unequal- rate of expansion in the more healthy and in the siseased areas of the leaves.

TOBACCO DISEASES.

Pate I—Tobacco leaf showing Mosaic Disease.

90 OHIO EXPERIMENT STATION: BULLETIN 156.

Possibly no other type of plant disease has so long resisted the efforts of investigators to discover the cause producing it. It seems now that we must class the mosaic disease of tobacco, the yellows of the peach, peach rosette, the mosaic disease of tomatoes and the mosaic disease of forcing house cucumbers, which the writer has recently investigated at Ashtabula, Ohio, in one and the same group of maladies. To discover the actual cause, or causes of these diseases has long been the aim of students of plant pathol- ogy. In recent years decided progress appears to have been made; but as yet the final word is to be said on this matter of cause. Mayer’ early made a careful study of the disease. He showed that the disease is transmitted by inoculation and concluded that it must be the work of bacteria. In 1898 Beijerinck” made a decided contri- bution. He showed that the juice of diseased plants, filtered through porcelain filters, yet retained the power of producing the disease when a small drop of it was injected intoagrowing bud of a healthy plant; he also found that diseased tissue kept these infectious qualities even after drying and retained its injurious properties in the soil during the winter; he further demonstrated that the so‘l around the roots of diseased plants may affect the roots of healthy plants. Studies of the disease have been made in our country by Sturgis’ and by Woods”. The lest named publication will be of very great value to any one who wishes to study the conditions surround- ing the production of the mosaic disease in tobacco. Just as in a sense Beijerinck was the discoverer of what he called “a living fluid contagium”’ which he regarded as the cause of the .disease, Woods was able to go further and ascertain the presence of certain enzyms in the plants known as oxidizing ferments and named ovédase and peroxigase. Both these investigators were able to transmit the dis- ease by inoculation of fluid from diseased plants into the young por- tions of healthy plants. The difference between the results of the one and the other is in the specific designation by Woods of the oxi- dizing enzym as the active agent in producing the disease.

'Mayer, Adolph, Ueber die Mosaikkrankheit des Tabaks. ieee Versuch Station 32:451-467 pl. I (1886). Review in Jour. Mycol. 7:382-385.

*Beijerinck, M. W., Verhandelingen der Koninklijke. Akademie van Weten schappen te Amsterdam, Deel © No. 5. See also Centb. f. Bakt. Par. &c., II, 5:27-33 (1899).

sSturgis, W. C., Conn. Exp. Station, Report (1898), 250-254.

*Woods, Albert F., The Destruction of Chlorophyll by Oxidizing Enzymes. Centbl. f. Bakt. Par. &c. II, 5.745 (1899).

5Woods, A. F., Observations onthe Mosaic Disease of Tobacco. Bull. Bureau of Plant Industry, U. S. D. A. 18:1-24, pl. I-VI.

TOBACCO DISEASES. 91

More recently still Hunger’ has investigated the mosaic disease of Deli (Sumatra) tobacco. Hunger’s observations had led him to believe that the disease may be communicated by touching first diseased then healthy plants, as when the coolies seek for the young worms, that is, the larve which eat the tobacco leaves. He planned and carried forward an experiment, using a definite system in the matter of touching, and found as a result that a very high percentage of the healthy plants, touched directly after a diseased plant had been touched in the same tour, became diseased. Hunger has contended, as a result of his latest work, that not only is the disease infectious by means of the fluid extracts from diseased plants, but it is also infectious, we may almost say contagious, by this method of touching.

It has been customary to speak of the mosaic disease as a phys- iological one, because no parasites in the sense of living or parasitic organisms are associated -withit. I have for the present contented myself with calling it a non-parasitic disease.

EXPERIMENTS TO DETERMINE COMMUNICABILITY OF MOSAIC DISEASE.

In 1904, under the direction of the writer, Mr. True Houser, field assistant of the department, conducted experiments in the plots of the test farm at Germantown along the line suggested by Hunger’s work on Deli tobacco. A few inoculation tests were also made, including in all 30 plants. The plants were inoculated in different ways; some by insertion of a small fragment from a diseased plant in an incision of a healthy plant; others by injection of awatery extract of diseased plants into healthy plants. In every case the inoculated plants contracted the mosaic disease, the length of time a’ter inoculation befere appearance of evidence of the dis- ease varying from one to two weeks, usually from 9 to 12 days.

There was no apparent difference between those inoculated near the base and those inoculated in the tender portion, although, asa rule, only the new growth showed the evidence of the disease. In some instances, where rather young leaves were inoculated, the disease afterward appeared. In this connection inoculations were made of extracts from plants suffering with what is locally known as yellow french, wherein the plant has a general yellow aspect.

Hunger, F. W. T., De mozaiek-ziekte bij deli-tabak. Deel I. Verslag van de op Deli met betrekking tot de Mozaiek-ziekte genomen proeven in de jaren 1901-1902. Med. s’ Lands Plantentuin 63, Batavia, 1903.

*Hunger F. W. T , Die Verbreitung der Mosaik krankheit infolge der Bc- handlung des Tabaks. Centbl. f. bakt. Par & c IT, 11:405-408. (1904).

Drief resume of Par. 4, Med. s’ Lands Plantentuin, 63 (1903) contributed

y the author. .

92 OHIO EXPERIMENT STATION: BULLETIN 156.

No result was obtained and no communication of the yellow condition, thus confirming an opinion previously held that this discoloration is due to the influence of unfavorable soii conditions.

- Blossoms of various plants were inoculated through the nectar by transmission of nectar from diseased plants, as by insect visit- ation. A slender brush of horse hair was used for this purpose. No evidences of disease were observed as a result of this method.

MOSAIC DISEASE COMMUNICATED BY TOUCHING.

The touching experiments were planned to test the danger of communicating the disease through handling first diseased then healthy plants, as in the operations of transplanting, worming, etc. The touched plants were arranged in sets of eleven plants each. In each set were three series of three plants each, marked a, 6 and c, respectively. The plant @ of each series was touched directly after touching a diseased plant then 4 and cin succession without retouching a diseased plant. Series 1 was touched but once; Series 2, twice on succeeding days; and Series 3, three times on successive days. The same plant was used for c of both Series 1 and 2, or of Series 2 and 3, making a total of eight plants for the three series. ‘The three remaining plants were treated as follows: one marked P was touched with considerable pressure (in some cases sufficient to break open the tissues of the leaf) after having done likewise to a diseased plant; one marked .S was touched upon the stalk; and the remaining one, marked Z, was touched upon the lower leaves. The last three plants mentioned were touched twice on succeeding days.

In all cases, where no’ otherwise stated, the touching was done on the upper or middle leaves.

Over 400 plants were touched, but owing to circumstances which prevented the collection of sufficient data from part of them, those with insufficient data have been omitted in the table. After the touching, the disease becomes visible, if communicated, only upon the new growth and is to be studied as in the cases of inoculation.

To insure against unintentional touching, the healthy and dis- eased plants were wormed and topped at separate times. The following table shows in the first part the results obtained upon touching the plants as determined upon the dates given, and also the increase of disease in the surrounding portions of the field. It will be observed from this table that the lowest percentage of plants becoming diseased under the 1c heading was 35.7 per cent., while the highest was 90 per cent., and the average of all the tests,

TOBACCO DISEASES. 93

after the lapse of one month, gave an increase of disease due to this cause amounting to 68.66 per cent. Against this increase in the ex- periment was an increase of less than 3 per cent in the surrounding plots described in Table I as “not touched.”” These experiments confirm the results obtained by Hunger and show the necessity of great care if the spread of this contagious disease is to be checked. In the light of these experiments of 1904, it seems highly probable that the inferences made in 1903, as to the spread of the disease ‘in the handling of the seedling plants, or otherwise, during the field practice of that year, are well founded.

TABLE I—Showing the results of observations and experiments as to the spread of the mosaic disease in tobasco upon ordinary plants and upon those touched with fingers after previous touching of diseased plants.

PLANTS TOUCHED

Manner} Total Plants diseased | Increase of disease) Total of disease Date of of No. by Aug. 12. from Aug.12-Aug.31} up to Aug. 31. touchiny. of eoebing |) plants: No. Per cent.| No. jPer cent.|| No. |Per cent. July 26-20 .-...... scheme 3a 20 16 80 2 | 10 18 90

ro. ole 3b 20 lL 55 7 35 18 90 ee ae ge reer oe 3c 6 2 33.3 3 50 5 83.3 bee Ga Sek oT 2a 20 8 40 5 | 2% Bo 65 ReMi Maire Gses frastivta. sins 2b 20 8 40 8 40 16 80 TBE ee ee SENS. la 20 7 35 2 10 9 45 ‘Sirs aus" aoe Ib 20 6 30 3 15 Weed 45 AS Might bee agree cae Ic 14 4 28.6 1 (fell 5 30 7 Hommes lai ere tel ce. : 2-8¢ 14 4 28.6 6 42.8 10 71.4 : Been aeraeas seine. 12 20 12 GO 5 25 17 85 a ed ode Saha hiais Ss 20 10 Ha) 4 20 14 70

Soe Cae a Onee L 20 6 ra) 6 30 12 60 Ss a ait actos ooo Se 1-2c 6 2 33.3 3 50 5) 83.3

Gramd totat ow fb Pls. 220 96 45.66 | 55 | 25 151 | 68.6 PLANTS NOT TOUCHED .* | | 6012 | 92 | 1.53 77 1.28 286 4.76

*At the beginning of the experiment, 119 plants of the total number, 6,012, or 1.98 per cent. were dis

eased in the areas herein studied, PREVALENCE OF MOSAIC DISEASE IN SOUTHWESTERN OHIO.

The writer and Mr. True Houser have studied the disease in the Germantown district during the seasons of 1903 and 1904. Taking some 12 farms in the vicinity of Germantown, Montgomery county, including the Station test farm, there was not a single farm on which the mosaic disease did not occur in 1903. ‘The varieties grown here are chiefly a cigar leaf filler. known as the ‘“‘Zimmer’”’

94 OHIO EXPERIMENT STATION: BULLETIN 156.

and the Connecticut seed leaf. The percentage of diseased plants varied from less than 1 per cent. to 43.5 per cent. in these scattered areas. Upon the Station t-s* farm, where 9'-1ting was deferred untu somewhat late, owing to de.ays incideat*o ¢lotting and ditching the | tobacco areas, a very curious but withal interesting state of facts was found to hold true in 1903. As is common in tobacco fields, the plots were of a definite number of rows and the results have been calculated dealing with the row as a unit, with the plot as a unit, with the fertilized plots and with the unfertilized plots of the area. The variations range from 0 to 56 per cent. of diseased plants in individual rows of the several plots and from 0 to 38 per cent. in the plants of the whole plot. No differences were discov- ered as between fertilized and unfertilized plots. To the writer it appears that the most striking feature exists in the extremely wide variation in the number of diseased plants in different rows of the same plot. Statedin its briefest form, we may repeat that the per- centage of diseased plants varies from nothing—that is no diseased plants—to a little over half (56 per cent) inindividual rows, and oc- casionally this range is found within the same plot. Possible explanations of this variation in the amount of disease occur to one. First, although the plants were set by machine, they were handled in removal from the plant bed, and the tendency would probabiy be to gather the plants from a limited area into a single bunch. Such bunches might represent a large number of plants diseased in the plant bed, despite the intention to reject diseased plants. Sec- ond, the apparent contiguous, or more or less contiguous situation of the diseased plants in the row may arise from the communica- tion of the disease after the manner described by Hunger, as above quoted. That there was in these plots late occurrence of the disease is shown by the fact that one or more stalks in the plot, which had been shorn of the later branches of the panicle to preserve a few early blossoms for seed, became subsequently diseased. The lateness of this discovery prevented carrying out a series of carefully planned observations, as suggested by the facts already given. In 1904 the seeds from a diseased plant of 1903 were planted at Wooster but no disease occured in the progeny. PREVENTIVE SUGGESTIONS.

Our preventive suggestions must finally be based on fuller knowledge than we now possess. ‘Two suggestions stand out prominently in the light of the observations made during the past two seasons at Germantown.

TOBACCO DISEASES. 95

First, all plants showing disease in the plant bed should be removed. |

Second, it will be found advisable to destroy the diseased plants in the field after removal.

The reason for the first suggestion will be evident and need not be further discussed. The basis of the second suggestion is the proved communication by touching, first, diseased then healthy plants. This amounted to about 69 per cent. of infection in 1904. (See Table I). It is recognized that we must know more of the actual losses, both as to quantity and quality, resulting from the mosaic disease before we can secure the largest interest on the part of the practical tobacco grower.

Koning’ has already shown the need for care in topping. In this, he reported the result of an experiment on a large scale, in 1897, in which diseased plants were first topped and directly a great number of healthy plants had tops broken by means of the fingers infected by the diseased plants; 88 per cent. of these healthy plants afterwards became diseased. It is clear therefore that any hand- ling of the plants must discriminate between healthy and diseased ones. ‘To top, worm and sucker diseased and healthy plants separately at different times, with disinfection of the hands before passing from the diseased to the healthy, is essential if.we hope to limit the spread of the mosaic disease in the field after it once appears.

II. PARASITIC DISEASES OF TOBACCO. a. DUE TO PARASITIC FUNGI AND BACTERIA. 1. ROOT ROT (BLACK ROOT).

In 1899 the writer received from Mr. B. W. White, of Neville, Clermont county, Ohio, specimen plants of size for resetting, the roots of which were attacked by a fungous disease which they had designated “black root”. This trouble was described as being very bad wherever beds were made the second or third year upon ground that had been devcted previously to the seed bed.. The roots of the plants were discolored externally, especially on the shin or internode immediately above the earth’s surface, often accompanied by cracking and deformation (Fig. 1.). A brief examination with the microscope disclosed the constant presence of the very characteristic parasitic fungus which we may call the tobacco root rot fungus, 7/zelavia basicola Zopf’ (Fig. 2).

‘Koning, C. J., Die Flecken- oder Mosaikkrankheit des hollandischen Tabaks. Zeitschr. fur Pflanzenkr. 9:55-80 (1899).

*Zopf, Die Pilze. 1890, page 97.

Yo OHIO EXPERIMENT STATION: BULLETIN 156.

From a drawing by F. M. Van Fook.

Fic. 1—Tobacco seedling affected with root rot.

So far as known to the writer, this is the earliest reported oc- currence of this fungus upon the roots of tobacco in America, and of this a note was presented before the Botanical Club of the American Association for the Advancement of Science, at its Pittsburg meet- ing. (See Science, new series, 1900.) Peglion' has earlier reported upon the root rot of tobacco in Italy, attributed to the same fungus, and in America Thaxter has reported its occurrence as a root rot of the violet.” Some years ago the writer studied the fungus in connection with nematode enlargements upon the roots of the cul- tivated Begonia rubra.* Latterly, in 1903, similar specimens were received from the plant beds of the Station test farm at German- town. ‘The Assistant Pathologist, J. M. Van Hook, has recently discovered 7%irelavia producing root-rot of ginseng. In the first case mentioned, from Clermont county, the variety of tobacco was

1Attid. R. Aced. Lincei CCXCIX, V. I-II pp. 32-99.

*Report Conn. Agr. Exp. Station 13:166-167 (1891). SBulletin Ohio Agricultural Experiment Station, 73:228. (1896)

TOBACCO DISEASES. | 97°

White Burley; the Germantown specimens were of a different vari- ety. It is apparent that we have here a parasitic root rot disease which, while manifesting itself more conspicuously upon the young plants in the plant bed, may be com- municated to the larger plants of the field should any diseased ones es- cape rejection. Aside from the dark color due to the reaction~:between the parasitic fungus and the host on the dis- eased areas, the symptoms of the dis- ease are not different from other inju- rious root diseases.

In the matter of preventive measures it is clear, from the Clermont county ex- perience that, plant beds should be made upon new earth each year. Further-

more, all plants with black root should be From a drawing by FM. Van Hook. | rejected in resetting. The field develop- Fic. 2—The fungus of tobacco root rot : 5

Thielavia basicola Zopi. Camera lucida yspent of the trou ble remains open for drawing of the fungus as it occurs Bpey ]

ginseng, tobacco and begonia. @ an r with us.

conidial forms; ¢ ascospores. All mag- study Wat

nified 665 diameters.

23 BED ROT:

On June 22d, of the present year, the writer observed areas, in the plant beds of the Germantown test farm, in which the plants had damped off, or rotted, asa result of the attacks of some specific fungus. The destruction in these areas was strongly marked and the diseased plants showed all gradations from fallen to lesion-marked stages of the disease. (See Plate II). Specimens were collected and photographed and microscopic examinations were also made. ‘These show that we have here injury due to the fungus /?hizoctonia. It is not possible at this time to state any further specific characteristics of the fungus, which does not appear to differ essentially from its forms upon other plants, in- cluding the potato.

The source of the /?eAizo tonia appears to have been in the soil employed or in the added manures. It is evident that we have here to deal with a plant bed trouble (which we have named dcd rot) of possible serious character, as well as with the root-rot pre- viously described. The occurence of this bed rot warns against -e-seeding in old plant beds. It is quite possible that soil treat- -aent with formalin, of the strength employed for potato treatment

98 OHIO EXPERIMENT STATION: BULLETIN 156.

From a photograph by F M. Van Hook.

Priate I--Bed rot of tobacco seedlings. produced by the fungus Rhizoctonia.

ae

TOBACCO DISEASES. 99

might improve conditions, but the chances are much against the successful use of formalin in earth where tender seedlings, like those of tobacco, are to be grown and transplanted. It is neces- sary in all such cases to reject diseased plants. It does not appear that this fungus has been previously investigated in its capacity to injure tobacco. Subsequent to the bed studies, or during August, plants in the field were observed showing peculiar injury ina rib- bon like band extending frem root almost to the growing tip. These plants tend to wilt down and especially to turn to the side with this ribbon lesion. The injury, we have determined, is asso- ciated with the bed rot trouble and doubtless results from the transplanting of some seedlings marked by this fungus.

3. DECAY OF TOBACCO SEEDLINGS.

Behrens’ has described a wilting and decaying of tobacco seed- lings, in which the symptoms consist of a wilting and a slime lixe covering of the wilted parts. With this a dirty green color 1; noticed, previous to becoming black. In the later stages a fungus may be seen covering the parts, especially the young secd leaves. This is identified by Behrens asa species of A/fernaria, possitly identical with A. fenu/s. While it is possible that this disease may have been met with in the young seedlings of the plant bed in our tobacco districts, it has not been my privilege toexamine specimens’ as yet. Tobacco growers are solicited to send specimens of the young seedlings which may be found drooping, or dying, in tie plant bed.

4. THE GRANVILLE TOBACCO WILT.

Within the past three years a destructive wilt of tobacco has been studied in Granville county, North Carolina. The symptoms’ are described as a drooping of the leaves, which soon become soft and flabby, as if suffering from want of water. Asa rule, the lower leaves droop first, the wilting gradually proceeding from the ground upward. Frequently the leaves of one side of the plant succumb earlier than those of the other. Often even a single leaf wil show only one side infected. The wilted leaves soon die, dry ud, and eventually the whole stalk dies, but remains standing with its dead leaves still hanging, and isnot to be confounded with the temporary wilt due to lack of moisture, excessive heat, etc. At the stage of ear-

1Behrens. J., Ueber den Schwamm der Tabaksetzlinge. Zeitschr. f. Pflanzenlcr, 2:327-332;, (1892).

’See Bull. N. C. Agr. Exp. Station 188: (1903). ‘‘The Granville Tobacco Nile: 2

100 OHIO EXPERIMENT STATION: BULLETIN 156.

liest wilting a section across the stem shows discoloration of the woody portion; at more advanced stages the wood is found, either ‘in its internal or outer parts, to be punctured with longitudinal black stripes. I have been informed that this disease was ob- served in the vicinity of Germantown during 1903. The disease differs from that known as “‘sore shin” in the south, in that the stem of the wilt-affected plant never topples over from loss of roots, as is true in sore shin.

Fic. 3—Tobacco plant attacked by the Granville, North Carolina, tobacco wilt. (from Bulletin 188, North Carolina Experiment Station.) CAUSES OF THE GRANVILLE TOBACCO WILT.

Two studies have been published up to this time with respect to the cause of the Granville tobacco wilt. The one by Stevens and Sackett (North Carolina Agricultural Experiment Station Bulletin 188, September, 1903) the other by R. E. McKenney (Bu- reau of Plant Industry, Bull. 51, 1903.) Stevens and Sackett have at- tributed the disease toa species of bacterium and have produced the disease from cultures of the germ obtained from affected plants.

TOBACCO DISEASES. 10]

McKenney, on the other hand, has found the conidia of a fusarium in the vessels of diseased plants and attributes the causal relations to the fusarium, which also causes wilting of cotton, cowpea and other plants. Whether it may be found upon another investigation that one or both of the organisms suggested are the cause of this - wilt, we apparently have here a parasitic disease of which the cause is propagated in the soil and is peculiarly adapted to be destructive in case the same soil is planted successively in tobacco. With dis- eases of this kind we are sure that crop rotation becomes a neces- sity, and soil which produces the disease may be regarded as “tobacco sick’. The writer would be very much pleased to re- ceive information concerning the occurrence of this trouble, or of similar troubles, in Ohio tobacco fields. I am indebted to Pro- fessor Stevens for the illustration of this wilt (ig. 3). 5. LEAF BLIGHT (FROG EYE).

Tobacco, in common with most foliage plants, is attacked by more than one species of parasitic fungus which produces abnor- mal conditions in the leaves. Of this the leaf blight fungus, Cercos- pora nicotianw, Eilis & Everhart, isone. This trouble has been de- scribed by Sturgis’ as occurring in North Carolina. The writer has met with various spotting conditions on tobacco in Ohio and inserts this note respecting leaf blight to bring forward observations in this line.

6. WHITE SPECK AND BROWN SPOT.

From North Carolina has come to us the description of another disease of tobacco, under the name of white speck, attributed to the fungus J/acrosporium tadscinum Ellis & Everhart’. . Another species of the same genus Muacrosporium longipes K. & E.” is cred- ited in the same state as the cause of brown spot.

7-8. DOWNY AND POWDERY MILDEW.

In Java, Van Breda de Haan has reported both a powdery and downy mildew of tobacco and referred them respectively to Erysiphe communis, (Wallr.) Ley. and Phytophora nicotiane n. sp. In Australia these mildews are reported and referred tothe same fungi. The downy mildew, should it occur with us, may be expected to prove destructive. The destructive character of the downy mildew of cucumbers as well as the downy mildew or rot fungus of the potato may be recalled in this connection. The powdery mildew of the pea and of many weeds and other plants, as well as this one of tobacco, may be expected to disclose themselves by a whitish covering of the growth of the fungus and is much less liable to prove destruc- tive.

IReport Conn. Agr. Exp. Station, 20:273-277 1896. 2See Journa: of Mycology 7:134, 1892.

702 OHIO EXPERIMENT STATION: BULLETIN 156.

6. DUE TO PARASITIC FLOWERING PLANTS. 9, BROOM RAPE OF TOBACCO AND HEMP.

The most of our plant diseases, as we use the term, are pro- duced by theattacks of parasitic fungi and bacteria. A few diseases, however, are due to parasitic flowering plants, such as the dodders which attack flax, alfalfa, cloverand certain wild plants. These dod- ders are like other flowering plants, produced from seed -which has matured in seed pods or capsules, but they are strongly marked by the absence of green foliage; being parasites these have not the ne- cessity for chlorophyll to be acted upon by sunlight in elaborating food, so the plant does without the green leaves. Broom rapes, which are likewise parasitic flowering plants, are analogous ina certain way to the dodders but, different in that the broom rape is attached to un- derground parts of the host plant—that is to the roots—while the dodders become attachedto the parts above the earth.

The broom rape of tobacco, Orobanche ramosa L. was earlier known in Kentucky upon hemp than upon tobacco; it attacks also the tomato, rape, cabbage, parsnip, etc., and is known in Japan, India, Europe and the United States. It has been described and illustrated by Garman™*. It is from the last named bulletin by Garman that we note the host plants of the different species of broom rapes. In this (Bulletin 105) Garman reports the occurrence of Orobanche luduvania on tobacco in Davis county, Kentucky. ‘The nearest allies, among our common native plants, of this tobacco broom rape are the beech drops and the squaw root; also the flowering broom rape, which the writer has collected in the vicinity of Columbus. Any one who is particularly interested in the broom rapes of cultivated plants will do well to consult Professor Gar- man’s Bulletin 105. The accompanying illustrations, Plates III, IV and V will show the manner in which the broom rape occurs in Ohio tobacco fields. It has been reported to the writer from a small area near Neville, Clermont county, for several years past. Specimens were sent tome by Mr. White, in 1901. The photo- graphs from which the half tones were made were taken by the writer in September of the present year. It will be noted that the plants growing under the central tobacco plant of Plate III are in bloom, and this broom rape produces seed freely, so that it may be dispersed in the seed pod or through the seedsof plants like hemp and tobacco. It would appear less likely to become ad-

“The Hemp Broom Rape of Tobacco. Bull. Ken. Agr. Exp. Sta., 24: 1890; &

Annnal Rpt. Ken. Agr. Exp. Sta., 1890, pp. 57-73, with 8 figures.. Also Bull. Ken. Agr. Exp. Sta. 105, Mch. 1903.

TOBACCO DISEASES.

Photograph by A.

IlI— White Burley tobacco plant attacked by broom rape. Ovobanche +

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104 UuiO EXPERIMENT STATION: BULLETIN 150.

/ vom a photograph by A, D. Selby.

PLare 1V—Showing tobacco broom rape, Orobanche ramosa, fully developed on root of tobacco plant.

105

TOBACCO DISEASES.

‘*

From a photograph by A. D, Sclby.

PLATE V—Various stages in the development of the tobacco broom rape, Orobanche ramosa, upon the roots of tobacco.

106 OHIO EXPERIMENT STATION: BULLETIN 156.

mixed with tobacco seed. owing to the manner in which the tobacco seedis usually harvested. Theareaofinfectionin Ohio is smalland confined to somewhat low bottoms skirting the river upon two different farms in Washington township, Clermont county. Infec- tion here may have come from the transporting of seed by the water or it may have come from another source. The clus ters of the broom rape often attain a very large size after the har- vesting of the tobacco.. The amount of seed produced must be considerable, so that it will be difficult to get these tracts of land entirely free from the broom rape, so long as tobacco growing is practiced at intervals. We have no evidence from the small area in Ohio as to attack on other plants, but Garman states that in Kentucky, infested land may be devoted to grains or grasses with safety. Caution is advised with respect to the growing of tobacco plants upon soil which is even suspicious. It will be a great draw- back to tobacco culture to have other areas of the state so infested with rape as are many of the hemp and tobacco lands in Kentucky. The fact that it occurs in Ohio on tobacco would serve as a warning against its further distribution within the state.

c. CURING HOUSE TROUBLES OF TOBACCO.

The tobacco diseases previously discussed relate to the growing tobacco plant; other troubles of the curing house, that likewise cause loss and impair the quality of tobacco, sometimes occur. Those engaged in the curing and subsequent handling of tobacco will recall many unfavorable conditions, which tend to affect the quality of the crop, aside from its original quality when first cured. The fermentations in the process of curing are regarded as essen- tial to proper flavor, but unless properly controlled these fermenta- tions may produce unfavorable results.

10. POLE BURN OR POLE ROT.

This is a disease of the curing house, referred by tobacco growers to the effects of warm, damp, foggy weather upon the newly hung tobacco. The first symptom is noticed in the neighbor- hood of the veins and the midrib of the leaves where moisture is abundant; later on the disease may extend. Sturgis has given usa very full description in the Connecticut Station report for 1891, pages 168-184. The entire contents of the curing barn may be leit quite worthless as tobacco by the extension of the deadly burn fun- gus. The disease may certainly be expected in every tobacco area in our country, as it has been known to exist in the past in Connecti- cut, Virginia, Kentucky, &c. The too close hanging of the tobacco,

TOBACCO DISEASES. 107

with the weather conditions already noted, will be likely to aggra- vate the trouble very greatly; while more room and a limited amount of artificial heat will be found to be favorable. Insufficient ventilation willlead to bad curing. The actual organisms of the decay have been studied by Sturgis, but it is doubtful whether

these are peculiar to this form of decay as against any other decays of vegetable tissues.

11. STEM ROT.

When the tobacco stalks are hung up in the curing house the leaves wilt and later dry up more or less, while the thick, succulent stem dries out but slowly. Under conditions which may prove unfavorable to the drying out, or even under average conditions, the danger of rotting at the stem is considerable. The stem rotisa disease of this character. It begins by white patches of a velvety aspect upon the diseased parts, more especially the stem. ‘The patches may spread to the veins of the leaf and induce unfavor- able results. Sturgis’ has reported upon this disease and found it to be due in Connecticut to a fungus known as JSotrytrs longibra- chiata, and Behrens’ agrees with Sturgis except that he regards this Botrytis longibrachiata as a form of PB. cinerea.

REMEDIES FOR STEM ROT.

In the curing house, this is usually remedied by gathering the diseased stems and destroying them and by the use of germi- cidal sprays in houses where the trouble has been serious. A spray consisting of formalin of the strength employed for potato scab should be very useful for this purpose and may be scattered throughout the building by using an ordinary spray pump, suchas is employed in orchards.

_ NOTES ON CURING HOUSE TROUBLE SOLICITED.

In order to present before tobacco growers some of the con- ditions recognized elsewhere, these brief abstracts of curing house troubles have been given in this bulletin. More complete notes and advices as to the occurrence of curing house troubles will be thank- fully received and will meet with response. It will be difficult to state just what our peculiar conditions may bring forth in Ohio until strict study has been made of these conditions in the curing house.

1Rpt. Conn. Agr. Exp. Sta. 15:184-186 1891.

2Trockene und nasse Faule des Tabaks. ,,Der Dachbrand‘‘ (Zeitschr. f. Pflanzenkr. 3:82. 1893.

108 OHIO EXPERIMENT STATION: BULLETIN 156. II. TOBACCO BREEDING.

PRELIMINARY STATEMENT CONCERNING SELECTION AND CROSSING OF TOBACCO IN RELATION TO NEW VARIETIES.

Since the establishment of the southwestern test farm of this Station, through the efforts of the Germantown Tobacco Growers’ Association, the various phases of the local tobacco problems have been under study. The Department of Plant Physiology and Pathology has been requested to take up the question of producing, or securing new varieties of tobacco for “cigar filler’? purposes.

In the various efforts made during the past two years, the results of which are in part indicated on subsequent pages, the botanist has been assisted by Mr. True Houser, field assistant of the department. The crossing and selection work has béen done by him under the direction of the writer, who wishes to express his obligation to Mr. Houser for efficient assistance.

It has been stated by many prominent tobacco growers that the Zimmer variety, so long grown for locally, cigar filer does not meet all requirements, and that, therefore, new varieties should be sought. In undertaking an investigation of this character the general principles involved are not essentially different from those in other jlines of plant breeding. "The methods may be stated in brief to consist either (1) in selection or (2) in crossing followed

*

by selection. _SELECTION- PROCESSES.

In the method of selection, new strains of established varieties are obtained by the choice of individual growing plants of the de- sired type, or types. These growing plants may be in special gardens or simply in the tobacco field. When suitable types are discovered the specimens are protected by bagging from undeter- mined cross pollination, and the plant is permitted to ripen a few of the earlier seed pods. At the time of bagging the other branches of the cluster are clipped off; the bagging must, of course, be done previous to the opening of the first blossom. ‘The pro- geny from the selections thus made, must subsequently be grown,. and the product after curing and fermentation, submitted to the necessary tests to determine its quality and special adaptations. It is apparent upon reflection, that this method has its limitations in regard to the extent of difference between the variety grown and the desired variety. If the variety already under culture possesses most of the desired characteristics, then this method of selection will prove well adapted; if, on the other hand, a wide

TOBACCO P@EEDING. 109

difference exists between the variety grown and the ideal new variety, either the process by s*'~ction alone 1 1s" se laid aside, or a longer time allowed for the breeding work in order to secure tne finalend sought. The tendency of the variety under culture to variation will naturally influence greatly the length of time nec- essary to attain the ends in question. However, one serious difficulty in tobacco breeding, and this applies at all stages to both methods, is the relative immaturity of the tobacco plants at the time the seed selection must. be made. It is but fair to state in this connection that selection alone, if unsatisfactory, must give way to other processes of breeding, and that whatever work is done must be done under the limitations imposed by the course of development run by the plants of the tobacco upon which we work.

METHOD OF CROSSING AND SELECTION,

In the second method, namely, that of crossing followed by selection, we endeavor to secure the plants for subsequent selec- tion by crossing two given varieties. The nature of the tobacco flower and its adaptation to self-fertilization, as well as the labor necessary toinsure cross pollination, must be duly considered.

While tobacco blossoms are freely visited by birds and insects with long bills or probosces, such as the humming birds and the hawk moths which lay the eggs of the tobacco worm, thus con- tributing to cross pollination, the tobacco blossoms are seif. fertile without insect or other visitation. Their adaptation to insect visitation and attraction, through the nectariesof the blossom, are but a possible co-operation in the widespread cross pollination se- cured in the vegetable kingdom. If, therefore, we wish to cross- pollinize, the blossoms must be emasculated by removal of the im- mature anthers or pollen sacs, ata time just previous to the fall opening of the tobacco piossom. ‘This period is indicated both by the development of the corolia of the flower, including its chan-ze of color, and by the slight yellowing of the anthers, or pollen sacs, at the same time. The emasculated blossoms must then be protected from insect visitation, by covering with suitable bags of a hardened paper manufactured for this purpose. Since the anthers are re- moved before maturity, at this time the pistil is not mature, or receptive to pollen; tke receptivity continues for some days usually, unless pollination occurs. Ripened and bright yellow s from the sort it is desired to cross upon such an emasculated pistil, are chosen the next day, or subsequently, and upon the

*The bags used in this work were manufactured by Schmidt, Dusseldorff, Germauy, and may be obtained in various sizes.

110 OHIO EXPERIMENT STATION: BULLETIN 155.

cautious removal of the bag, applied to the stigmatic, or sticky surface of the pistil of theemasculated blossom. Caution in this manipulation is exercised so as toinsure only pollination by these chosen pollen sacs. Such crossing does not change the plants upon which it is performed, but the cross-fertilized seeds will be in- fluenced and grow, when sown, into plants having certain charac- teristics which resulted from the crossing. Usually these char- acteristics have been found to be more or less intermediate, varying from those plants showing very close resemblance to the one parent, by almost imperceptible gradations into types approaching the other parent. In our tobacco work, we have found thatin all, more strictly intermediate types have prevailed in the progeny; these types par- tale very decidedly of the characteristics of both parent varieties. The crosses thus far made, have included, more particularly, crosses between the large-leafed ‘Connecticut seed leaf” variety, and the slender variety grown in the Miami valley underthe name of “Cuban.” The illustrations will possibly show how the crosses exhibit the inter- mediate characters. Most of the crosses show much larger leaves than the Cuban, but with longer internodes than the Connecticut seed leaf. The actual qualities of the cured tobacco remain to be subsequently determined. SELECTION OF CROSSES.

In the manner above indicated, about 30 crosses were produced in 1903. The seed of some of these was lost, but 25 of them were grown during the season of 1904. These are recorded by the numbers under which the original cross-pollination was entered. In this instance, they run from No. 51 to No. 75, inclusive. The~ illustrations will show the variation in part. Another factor will be found in the yield of cured leaf, and still another in the quality of this leaf. For final application of the results of crosses, the favorable, or suitable sorts, must be determined by the processes of selection which have been heretofore discussed. ‘Ten out of the twenty-five varieties have been rejected, or at least set aside, and only fifteen of these are to be planted in 1905. ;

While, during 1904, only a single row of each number was grown in a plot, in 1905 duplicate 20th acre plots will be grown Of vediGn selected number, checked by standard plots of the Zimmer and grown along with plots of the ‘‘selection”’ strains of Zimmer and with plots of the Cuban and Connecticut'seed leaf. In this manner the habits of growth, productiveness and quality of the various crosses will be determined in the course of two to five years, ac- cording to the amount of retesting necessary.

TOBACCO BREEDING. 111

Numbers 53, 54, 55, 58, 59, 61, 63, 64, 68, 69, 70, 71, 72,74 and 75 have been selected for plot tests in 1905, while numbers 51, 52, 56, 57, 60, 62, 65, 66,67 and 73 have been set aside as of less apparent merit. It willthus be seen that the procedures in plant breeding require rather long periods of time; several years are ordinarily required in the selection of a suitable type, or variety, from crosses or from more or less fixed varieties already grown. It always remains to be determined, when across is grown, whether the plants are uniformly of one type, and if they are not, the sort must be grown repeatedly until the type is ‘“‘fixed.””. We made notes in’the field in 1904 which show that, with the crosses thus far studied, the variation among the plants of the rows of the same number in 1904, was much less than anticipated. It is expected therefore that the fixing of type with the tobacco crosses will be less prolonged than in the case of wheat and some other plants.

This statement of the processes employed and the progress made in breeding varieties of tobacco is published at this time, in order not only that the members of the legislature who, aided in the establishment of this tobacco test farm, and the members of the Tobacco Growers’ Association, may discover the manner in which the Station is carrying out its obligations, but also that the general tobacco growing public may know something of the operations in this line. Two or more years must yet elapse before the results of this tobacco breeding will merit further publication.

BULLETIN 150.

OHIO EXPERIMENT STATION

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From a photograph by A. D. Selby. Priate VII—Tobacco crosses of Connecticut Seed Leaf and Cuban varieties as grown in 1904. Nos. 71, 72, 74 and 75 have been selected for plot tests in 1905. No. 13 has been set aside as of less apparent merit.

BULLETIN 156.

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