12 



The Florists'^ Review 



.luiA- IS, 1911'. 



iiitcrcvis us ;ill jiliki'. 1 ;iih ;ilsn ylad to 

 take this (p|i|i(ii t iiii it v ami cxiiicss to 

 Von ill Ijchall' ol llic lirlawaif ('(illc^o 

 A^riciiltural I;\|m>i mifiii Statinii and of 

 the I ' II i \ci-<it y ni' 1 'iini-\ I \ aiiia (Mil' sin- 



iiTcsl a|i|ircciat ii f I lie kindiicss of 



all till' sridsincn wlio have so <^rii('r- 

 <iusly si'ijt lis sweet ]M'a seeds and thus 

 toiiiii'ii ilie nucleiis t'or our invest ij:a- 

 tioiis of the diseases uf tlie sweet 



^'oll^ |ireseilt speaker is a lo\iT of 

 tloweis aii<l es|M'cially a l(j\er of the 

 f-weet |ie;i. The more ot' this llower I 

 saw, llie niori» (■(iii\ini-eii did I hecimie 

 tiial the sweid jiea is f;ir from lieiiii: 

 ;is free from insect ;ind fungous attaidis 

 ;i'- the iiiiijority of tlie seedsmen and 

 i: row els iioiiestly Imt erroneously lie- 

 lie\-e. Ill some of our best ^vrittell 

 manuals on sweet ]ie;(s the topic of 

 insect and fungous diseases liardly oe- 

 ciipies one (|iiarler id' a pa^e. 



Too Long in the Same Soil. 



That the sweet pea is liecomiiiy more 

 popular with the American jieoide 



needs no |il(M,l'. it' once \\e ^row- 



sweet jieas. W(. will ^low them all the 

 linie. Jlowe\er. most amateurs, either 

 tor hick ol space or unknowingly, 

 glow their sWeet pe;is in the same lot 

 ye.'ir ;ifter year. The result is tliat 

 di^ea^c- sel ill ami make it impossihle 

 any longer to iirow sweet |ie;is on that 

 same place. Immetiiately the seeds: 

 are Idamed and the eiistoiner begins 

 changing trade from seedsman to sm'ds- 

 maii, hut with no hetter results. Thus 

 lack of information on the part of tlie 

 grower or amateur, on the one hand, 

 and tli" slowness of the seedsmen to 

 adiiiil tliat the sweet pi'as can he 

 trouldeil jiy diseases. oil the other, 

 cause the lr;ide iinarialily to sulfer. 

 Hence, when considered ]iur(dy mi 

 ;in economic hjisi'^. the seedsmen are the 

 losers. Whatever ilisease the seedsman 

 is Viiliing to admit, he usually throw-- 

 the Idanie to high feeding or to the drs 

 ^\ e;it lier. I'roni im|niries sent out 1o 

 nio^t of the seeilsinell who grow sweet 

 pea- in tin- country, only two \;igiiely 

 admitted tli.at their sweet jieas are 

 troillded with Might. 



The Need of Investigation. 



We do not tor one minute doiilit tiie 

 until of the statement-- of all these 



gentlemen, lillt we |jelie\e that if the 

 see<|smeii tool; this matter more seri- 

 ously, they \\ould Soon reali/e that 

 their interest !■- ;it stake. It is some 

 times good for all et us to lie Iroiii .Mis 

 soni'i, in order that we may he shown. 

 We wiiiild feid highly gratitied and our 

 elfolts would lie well repaid if We could 

 impress \(M1 \vitli the fact that -wcet 

 jieas sulfer from disea-es which are 

 caused liy either insects or p.'irasitic 

 fungi. It i- to the l.eiielit ot' the seeds 

 man ;ilid the welllieilig of the trade 

 to admit these facts and recognize the 

 necessity ot' iii\ est igatiiig these dis- 

 eases and linding remedies for them, 

 and of disseminating liioadcast the re 

 suits ol' these limlings to all tlio--e in 

 terested ill them. 



liefore entering into the discussion 

 jiroper ot' the diseases id' the sweet ])i'a. 

 we wish to state that the Delaw.are 

 AgricMiltiiral K.xperiment Station, in co 

 ojieration with the I'liivirsity of renii- 

 syhania, has nuule it ]io-^silde for your 

 jiresent speaker to cjirry on tor the last 

 two years in\'est i^at ions ot' the diseases 

 of the sweet ]iea. The iiit'ormat ion 

 which we are al.out to i!i\c is id' ne 



cessity of a preliminary nature, since 

 we have hy no me.aiis exhausted the 

 -llliject. Nevertheless, we helieve that 

 we have gathered enough to justit'v the 

 present .address. The informatiou is 

 lii-t h;iiid. .MS it is all the result of our 

 |iersoiial in. est igatioiis and studies in 

 lioth held ;iiid la lioi ;it ory. In >Ci'wark. 

 I'td.. we now have one halt' acre of 

 sweet peas devoted exclusively to the 

 study of tlie diseases. 



Diseases Under Glass. 



In dealing with the diseases of the 

 swv'et ]iea. we have to recognize two 

 t lasses: first, diseases of the sweet 

 pea grown under glass; second, dis- 

 easi^s of the sweet ]>i'a grown out of 

 doors. 



I'lider glass, sweet jieas are not as 

 exteiisixidy grown as out of doors. The 

 time is nndoiihtedly rapidly apjiro.'ich- 

 ing when the market will call for more 

 swe(>t ]H'as in the wiiit(>r. We have 

 no information as to how many .are 

 tictually engaged in growing winter 

 sweet peas, and the success or failure 

 with wliiidi these growers nuet. We 

 know of n few growers who have at- 

 teiii]pted to grow sw(M't ]ieas under 

 glass, hut who have failed. I'or the 

 lieiudit of the i(>st of us, we will here 

 consider some sjucilic cases, in order 

 to liiing to your attention some of the 

 possilde diseases which troulde sweet 

 peas under glass. 



One Grower's Experience. 



A grower — I cannot gi\(-' you the 

 name — ^erected a forcing house for the 

 purpose of growing winter sweet peas. 

 His iirst attempt was a failure. His 

 ]dants began to die in s])ots. and only 

 liere and there did a ]dant remain 

 ali\e. The grower soon complained to 

 his seedsman and the latter kindly re- 

 ferred him to us. We immedi.ately 

 asked for a complete history of the 

 trouble and for sjieidniens of the dis- 

 eased jilants and soil. The following 

 is the story of the troulde as told l>y 

 till' grower hinisidf: •'The house the 

 peas are in was built last suminer on a 

 jdece ot ground which had been in 

 grass for over li\e years. I bought 

 the ground si.x years ago from a farm 

 er \vlio had corn in it for several Acars. 

 but always ]ioor. I ga\e it u heavy 

 dressing of horse nianuie ;ind had it 

 ]doweil .and sown with Ixeiitu ky bine 

 grass, and red (do\er seeiled on it. The 

 grass -was :i f.ailure and the clover did 

 not come at all. When I ])laiited the 

 pe.as, I inanureil heav llv. appl\iiig about 

 four inches id' cow manure ;iiid some 

 little horse ni.'iiiure. Those that did 

 grow did llnidy; the rest were a failure. 

 It is ;iltogetlier a puz/le to me, -.nxl I 

 hope you will be able to get at the 

 root."' 



A Complication of Diseases. 



The di-easecj specimens which this 

 grower sent us revealed some highly in- 

 teresting things. It was pl;iiiily seen 

 that the |d;in1s sulfered from more than 

 one dise.ase. < )n the exterior the phaiits 

 looked healthy, but ;i idoser (>xamina- 

 tion revealed a \(dlowisli. sickly ap- 

 pearance. The seat of the trouble in 

 some cases was coiiliiied to the roots 

 only, and in others that ji.art of the 

 stem .just aboxe the roots, in tli(> first 

 instance we found a typic;il c;ise of eid- 

 worms, lleterodeiji radicicola. better 

 iviiowii ,'is root-knot disease. Those of 

 \-ou who grow \iolets ha\e surtdy nut 

 with this trfiuble. It is evident that 



roots cri|)]ded with eelworm canm 

 make much headway. Of the otiu 

 s|iecimeiis, where the sciit of the di 

 ease seemed to be located at the jun. 

 tioii between the roots and the sten 

 the latter was found to be covered wit 

 a white weft of line mycelium thrcao 

 of a j'uugus. (Jii splitting open th 

 stem, it was found to be fdled wit: 

 the same white mycidium and intei 

 mixed with small sclerotia. Culture 

 (d' this mycelial growth readily gav> 

 a ]iure culture of a sclerotiiiia. resem 

 bliiig in all appearances the Sclerotinia 

 libertinia, a fungus whiih causes tin 

 damping olf of lettuce and so niaiiv 

 other jilants. 



Due to Infected Soil. 



In order to establish definitely tin 

 relationship of this sclerotinia fungus 

 to this disease of sweet peas under 

 glass, sterilized seeds were planted in 

 sterilized pots and soil in the labora 

 tory. All the seeds germinated and 

 the ]dants were allowed to grow for 

 three weeks, with no disease appearing 

 on them. Then the pots were divided 

 into two lots. ()iie was left as a check 

 and the other was inoculated with the 

 pure culture of the sclerotinia by in- 

 troducing pieces of the fungus in the 

 soil. Both lots, check and infected 

 jdaiits, were covereil with bell jars to 

 imitate the moisture condition of the 

 greenhouse. After four to si.x days, 

 Avilting of the inoculated seedlings be 

 gan, whereas the checks remained 

 healthy. This was repeated several 

 times, with always the same results. 

 This conclusivcdy shows that the fun- 

 gus Sclerotinia libertinia will produce 

 a disease on sweet peas under glass 

 when juesent in the soil. This fungus 

 IS usually brought into the greenhouse 

 with the soil or with the manure. From 

 the account which the grower gave us, 

 it was purely a case of infected soil, 

 and this explains why his sweet jieas 

 failed. Cross inoculations with this 

 fungus from the sweet i>ea and the one 

 from lettuce produced typical cases of 

 wilt in each, thus proving comdusively 

 that this fungus from the sweet pea is 

 the same as the Siderotinia libertinia of 

 the lettuce, and that the sweet peas are 

 at stake if they are made to follow a 

 crop of lettuce which suffered from this 

 disease 



Investigating the Soil. 



Several other fungi were isolated 

 from the diseased stems and roots 

 ahove discussed. Tnociilations with 

 I'lire cultures of these fungi on healthy 

 seedlings jiro\ed to be active parasites. 

 We are not here giving our iiual word 

 on these fungi, as more ivxperiments 

 are still under way. 



While werking on the ilist\'ises of 

 the loots and steins we have also in- 

 \estigated the soil which was sent to 

 us by the grower, .\ccordingly, a few 

 sterilized pots were filled with the soil 

 and sterilizeil seeds planted in it, and a 

 tew other sterilized pots were lill(>il 

 with sterile soil and ;ilso sown with 

 steiili/.(>d seeds. The same amount of 

 seeds were ]danted in both lots of pots. 

 After ten days the seeds in the sterile 

 sidl germinated and grew well, while 

 the seeds in the sick soil germinated 

 only sparingly. I'pon idoser examina- 

 tion these noil germinated seeds were 

 found to be rotted, and of those few 

 plants which grinv one half had their 

 roots nearly rotted. In culturing 

 these roots the sjinie fungi were ob- 



