656 



HOKTICULTURE 



November 9, 1912 



PRESENT KNOWLEDGE OF SWEET 



PEA DISEASES AND THEIR 



CONTROL. 



A paper by J. J. Taulieubaus, Delaware 

 College Agricultural Experimeut Sta- 

 tion. Newark, Del., read before tbe 

 Americau .S\^'eet Pea Societ.v, 

 Boston. July 1.5. 1912. 



{Ccntinut'd from page Jj2) 



I have already mentioned the spot- 

 ted, or mottled disease of sweet peas 

 under glass. This is a new disease 

 to this country and it is a very dan- 

 gerous one. In its attacks it is not 

 restricted to greenhouse conditions 

 alone but it is also a serious disease 

 of sweet peas outdoors. For the sake 

 of convenience we will call this the 

 "mosaic disease." It is readily distin- 

 guished by a yellow dotting or mot- 

 tling of the leaf, presenting in some in- 

 stances a beautiful mosaic structure, 

 hence its name. Affected leaves seem 

 to linger for a time but they eventu- 

 ally lose all the chlorophyll and soon 

 drop off. A better symptom of this 

 disease is a curling of the leaves at the 

 tips, very much resembling the curling 

 of leaves induced by the green aphis, 

 but in this case the aphis has no asso- 

 ciation. The disease makes its ap- 

 pearance after the seedlings are from 

 three to four weeks old. Often, the 

 disease is so bad and the curling S3 

 pronounced that the plants thus af- 

 fected cannot make any headway and 

 remain dwarfed. An attempt is made 

 of these curled parts to produce a few 

 flowers, but the latter are borne on 

 very short peduncles as compared with 

 the long peduncles of healthy plants 

 of the same variety. Frequently, how- 

 ever, the affected plants outgrow the 

 disease entirely, and thus a distinct 

 line of demarcation can be made be- 

 tween the previously diseased part and 

 the healthy part of the new growth. 

 At other times infected plants keep on 

 growing, and even flowering, with the 

 disease keeping pace. Attempts to cul- 

 ture and to isolate the organism which 

 causes this mosaic disease have failed. 

 Like the Peach yellows, the mosaic 

 disease of the tobacco and tomatoes, 

 this mosaic disease of the sweet pea, 

 too, can be reproduced by a puncture 

 with a sterile needle from a diseased 

 into a healthy leaf. Yet no organism 

 could be obtained in culture, nor could 

 it be detected with the microscope. 

 Nevertheless, this disease is con- 

 tagious, as is the Peach yellows. 

 When the disease first made its ap- 

 pearance in our experimental sweet 

 pea field, the diseased areas were im- 

 mediately located in order to learn 

 something of the spread of the disease. 

 They formed two small areas, one in 

 about the center of the field, the other 

 in the southeast corner. Within ten 

 days another survey was made and the 

 whole field was found to be contam- 

 inated. With the exception of the 

 dwarf Cupid varieties, which are seem- 

 ingly immtme, all the rest were found 

 to be affected with the mosaic. When 

 first investigating this disease we 

 thought that, perhaps, this mottling of 

 the leaves was merely a variegated 

 condition. We also thought that per- 

 haps the curling of the tender tips as 

 well as the mosaic effect was due 

 primarily to the presence of aphids, 

 which at the beginning of the season 

 were so plentiful. Experiments were 

 then undertaken to determine definite- 

 ly these points. Accordingly, sterile 

 pots with sterile soil were planted 



£UlllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllUlllllllllllllllilllllllllllllllllllllllll!£ 



I LOBELIA CARDINALISl 



5 Most Beautiful Flower of New England, Perfectly S 



= Hardy; Grand for Bedding; Brilliant Scarlet Flowers, 5 



= Fine Strain of New Seed. 50c pkt. post paid. 5 



I Mt. Desert Nurseries Bar Harbor, Me. | 



^IllllllllllllllllllllllllllllllllllllllllllllllllllllllilllllllllllClllllllllllllllllillllllllllllllllllll^ 



with sterilized seeds. Each pot was 

 isolated in a glass chamber and the 

 plants were allowed to grow for three 

 weeks to see it any disease would de- 

 velop on them. However, the plants 

 remained very free from any diseases. 

 The pots with plants were then 

 divided into four lots; into lot 

 I. were introduced a few stem mothers 

 of aphids from affected mosaic plants 

 in the field. In lot II. were intrcduced 

 a few stem mother aphis, from appar- 

 ently healthy plants in the fields. The 

 plants in lot III. were punctured with 

 sterile needles and by pricking a 

 mosaic-affected leaf, and then punctur- 

 ing with the same needle the healthy 

 leaves. Lot IV. was merely punctured 

 with the sterile needle, and these weie 

 designed to serve as checks. In each 

 lot there were two pots with plants in 

 order to duplicate each experiment. 

 After ten days the lots which were 

 inoculated with the aphis from dis- 

 eased and healthy plants both began 

 to show the symptoms of mosaic. This 

 would therefore appear to show that 

 the mere puncture of aphis would be 

 responsible for the mosaic disease. 

 However, this is not the case, as we 

 will soon see. Moreover, it is easy 

 to suppose, and that on very good 

 grounds, that the aphis taken from 

 seemingly healthy plants in an infected 

 field might themselves have been in- 

 fected before. But this would be no 

 valid proof. Lot III., which was in- 

 fected with needle punctuies from dis- 

 eased leaves, began after ten days to 

 show the mosaic disease, while the 

 check punctures remained all healthy 

 to the end of the experiment. This 

 definitely proves that the aphids are 

 not the cause of the trouble but are 

 merely the carriers of the mosaic dis- 

 ease. It seems, therefore, that any 

 steps taken to control the aphids may 

 also serve to control the mosaic. From 

 this, too, it seems that not only the 

 aphis, but also any biting or sucking 

 insect may help to spread the disease. 



(To be continued ) 



CHICAGO NOTES. 



Theodore Vogel severed his connec- 

 tion with The Alpha Floral Co.'s re- 

 tail store on November 2nd. 



Fred Lautenschlager will represent 

 Kroeschell Bros, at the St. Paul 

 Flower Show, November 8-12. 



Ed. Eisner has closed his retail 

 store at 55th and Halsted streets and 

 the windows bear a "for rent" sign. 



Chas. Zapfe, 62nd street and South 

 Park avenue, is preparing to celebrate 

 in a fitting way the completion of 

 his first year in the retail business, 

 November 16th. 



The Chicago Flower Growers' Asso- 

 ciation has again added more growers 

 to its long list of stockholders. A 



project is under consideration where- 

 by the company hopes to build a range 

 of greenhouses of its own. 



Mr. and Mrs. A. E. Spencer of St. 

 Paul, Minn., visited Chicago on their 

 honeymoon trip. Mrs. Spencer, for- 

 merly Agnes C. O'Keefe. is proprie- 

 tor of the Swanson Flower Shop of 

 that city. 



Invitations have been received here 

 for the marriage of Alverta May Prall 

 and Arthur John Bauscher of Free- 

 port, 111., to take place at the home 

 of the bride's parents in that city, No- 

 vember 18th. The groom is a promis- 

 ing young florist. 



The new scarlet carnation. The Her- 

 ald, now offered for the first time 

 by the Chicago Carnation Co., is at- 

 tracting many visitors to the com- 

 pany's plant at Jollet. Last week visi- 

 tors from Oregon. California and Mex- 

 ico were among the number. 



Visitors: J. J. Karins, of H. A. 

 Dreer's, Philadelphia; Wra. Hild, 

 Milesville, S. D.; R. A. McPheron, 

 Litchfield, 111.; A. L. Glaser, Dubuque, 

 Iowa; Mr. and Mrs. A. E. Spencer, 

 St. Paul, Minn. 



HELP WANTED 



WANTED— Good, all-round man lor 

 violets. Single, good worker. B. Bingbam, 

 Pine Street. Dedbam, Mass. 



SEEDSMEN WANTED— Young men for 

 botli Vegetable Seed and Flower Seed De- 

 partments; mention .ige. experience, salary 

 anil reference. Peter Henderson & Co., 35 

 and 37 Cortland Street, New York City. 



S.VLESMAN of ability and reliability— 

 yonng or middle aged man of experience 

 in vegetable seeds, to cover wide range of 

 territory for old e.stablisbed wholesale 

 seed concern. State experience, references 

 and salary with first letter. Address "X," 

 care HORTICULTUKE. 



SITUATIONS WANTED 



POSITION in small private place, gar- 

 dening, dairy, coachman and general work. 

 John Toosey.' General Delivery, Hyde Park, 

 Mass 



POSITION with chance of advancement 

 with any up-to-date retail florist in Boston. 

 Young I'rotestant. having- had four years' 

 experience and willing to start at .flO.OT. 

 Am resident of Boston and can furnish 

 best of references as to character and 

 ability. Employed at present. Write to 

 C. W. H., 766 Central Avenue, Dover, N, H. 



FOR SALE 



FOE SALE— Retail Store in city of 

 16,000. Bargain. For full particulars ad- 

 dress "E," care H ORTICULTURE. 



FOR SALE — Fresh from factory, new; 

 10x12, 16x18. 10x24, double thick. A 

 and B qualities. Market dropped. Now la 

 the time to buy and save money. Parshel- 

 sky Bros.. Inc., 21.5-217 Maveraeyer St., 



Brooklyn, N. Y^ 



~FOR SALE; several thousand feet of 

 doulile thick greenhouse glass 10 x 15, 

 second hand, clean and good as new; also 

 one thousand feet •! in. cast Iron pipe and 

 one Hitchings No. S-16 greenhouse boiler, 

 very low price for cash and immediate 

 delivery. F. E. Palmer, Brookline, Mass. 



