280 



THE GARDENERS' CHRONICLE. 



[April 27, 1912. 





EDITORIAL NOTICE. 







ADVERTISEMENTS should be sent to the PUB- 

 LISHER, 41, Wellington Street, Covent Garden, 



Letters for Publication, as well as specimens of plants 

 for naming, should be addressed to the EDITORS, 

 4 1, Wellington Street, Covent Garden, London. 



Communications should be WRITTEN on onk side only of 

 the paper, sent as early in the week as possible and duly 

 signed by the writer. lfdesred, the signature will not be 

 printed, but kept as a guarantee of good faith. 



Special Notice to Correspondents.— The Editors do not 

 undertake to pay for any contributions or illustrations, or 

 to return unused communications or illustrations, unless by 

 special arrangement. The Editors do not hold themselves 

 responsible for any opinions expressed by their correspon- 

 dents. 



Local Hews.— Correspondents will greatly oblige by sending to 

 the Ed tors early intelligence of local events likely to be of 

 interest to our readers, or of any matters which it is desirable 

 to bring under the notice of horticulturists. 



disease seems to have abated somewhat and found that they suffered from 



ice but it is still very trouble- virulent attacks of the disease even when 



virule 



some, reducing the vitality of the affected there were no infected plants within a 



considerable distance. The rapid dissemi- 

 nation of the disease, at the time of its 



plants. 



The disease shows itself as a number 

 of brownish lumps or pustules, chiefly on appearance in Europe, also suggests very 

 the under-surface of the leaves. The pus- strongly that it must have been carried 



with the seeds and rootstocks. 



tules consist of masses of brownish spores, 



which in the presence of a suitable sup- Eriksson observed in his experiments 



ply of moisture germinate and -produce that seedlings sown in spring remain 



minute, colourless reproductive bodies, for the first three months completely free 



These can be carried in the air to other and then suddenly develop the disease, 



leaves and so produce again the disease. the pustules appearing in large numbers 



scattered regularly over the surface of the 

 leaf. As in the rusts, if infection takes 



APPOINTMENTS FOR THE ENSUING WEEK. 



TUESDAY, APRIL 30- , . . , 



Royal Hort. Soc. Corns, meet, and National Auricula 

 and Primula Soc. Sh. (Lecture at 8 p.m. by Dr. 

 Redclifte Salaman on u Potatos.") Hort. Club meeting. 



The germination of the spores can easily 

 be recognized with the naked eye, for 

 then the hemispherical clumps of spores place from outside, each pustule means a 



separate infection. It is pointed out that 



in situations where there are no in- 

 that fected plants in the neighbourhood the 



turn from brown to grey owing to tne pro- 

 duction of these smaller colourless bodies. 

 It is by means of the 



means 



carried 



AvitAGE Mean Temperature for the ensuing week 

 deduced from observations during the last Fifty Years 

 at Greenwich— 49 2°. 



spores 

 the disease is carried from plant to air can hardly be 

 plant during the growing season, but 



been considerable 



ductive bodies that 



so full 

 hundreds 



of repro- 

 of them 





Actual Temperatures :- 



London.— Wednesday, 



Min. 44*. 

 Gardeners' Chto 



there has always 



doubt as to the manner in which 



the fungus survives the winter. Whether 



Eriksson shows, 



can fall on a single leaf. 



moreover, that it is only the mature 



leaves of the young plant that show the 



April 24 (6 p.m.): Max. 66°; ^ living threads of the fungus exist disease, while if infection is external one 



Office, 41, Wellington Street, 

 Covent Garden, London —Thursday, April 25 

 (10 a.m.) : Bar. 299" ; Temp. 56"; Weather- 

 Sunshine. 

 Provinces.— Wednesday, April 24 : Max. 60° Cambridge ; 



Min. 50° Scotland, N.W. 



in 



the seed or remain throughout 



would expect the young delicate leaves to 



these and 



SALES FOR THE ENSUING WEEK. 



WEDNESDAY— . « «. • * io 



Herbaceous and Border Plants, Hardy Bulbs, &c, at 12 ; 



Liliums, &c, at 4; Palms and Plants at 5 ; at 67 & 68, 



Cheapside, E.C., by Protheroe & Morris. 



THURSDAY and FRIDAY- 



A collection of Choice Established Orchids, at 67 & b8 f 

 Cheap id *, E.C., by Protheroe & Morris. 



the winter in other parts of the plant, or be the first attacked. For 



whether the spores persist in the living other reasons Eriksson holds that the 



state during the winter on the seeds or first appearance of the disease in the 



on old living or dead leaves has been much spring is the result of an internal infection, 



disputed. due to the existence in the seed of a 



Eriksson, the Swedish botanist, has for mycoplasm similar to that which he had 



some years been investigating the rust of supposed to exist in the grains of Wheat. 



This disease is well known to 

 The gardeners for the damage it 



Hollyhock B 



and other Malvaceous plants. 



newcomer in 



South 



does to Hollyhocks, Mallows, 



Hollyhocks, and has lately published his 

 results in full. Eriksson is well known to 

 those who study diseases of plants for his 

 unconventional views as to the means by 

 which the rusts of Wheat persist from 

 season to season. The difficulties in 

 accounting for the sudden appearance and 

 rapid spread of epidemics of rust on 

 Wheat led him, about eleven years ago, 

 to put forward the view that the rust 



The observations of Eriksson certainly 

 support the views of gardeners as to 

 the transmissibility of the disease by 

 the seed, and this transmissibility may 



fact. The exact 



It is comparatively a 



Europe, for its original home is m 



America. The gradual spread of the Holly- fungus might exist in the seed in a special 



hock disease over Europe during the latter form known as mycoplasm. 



part of the last century is almost as Seeds from affected plants were sup- 



be accepted as a 

 mode of transmission is, however, much 

 more debatable. Some of the diffi- 

 culties in the way of the acceptance of 

 the mycoplasm theory have already been 

 presented, and in the absence of more 

 rigid proof that neither the threads of the 

 fungus nor spores are present in or on 



the seeds it must be considered as un- 



that while 



striking an example of the distribution of posed to bear within them, not the ordin- proved. It is noteworthy 



a plant disease as that of the Gooseberry- ary fungal threads which can be easily Eriksson states that the spores ot xn 



mildew in recent 



years. 

 1854 from 



It was first observed with the microscope, but a 



described in 1854 from some leaves of 

 Althaea officinalis sent from Chile, was 



peculiar combination of the living material 

 of the fungus with the living material of 



identified as a member of the well-known the seed. This combination, mycoplasm, is year are able 

 groups of fungi, the Rusts, and received hardly detectable as such even under high 

 the name of Puccinia Malvacearum. powers of the microscope, but is supposed 



Hollyhock Eust are unable to survive 

 winter in Sweden, yet it has been shown 

 that in America spores formed late one 



to germinate the next 



The fungus b?gan its wanderings by ap- to pass from the seed to the leaves as the 

 pearing in Australia in 1857, but did not plant develops. Finally, in the leaves, the 



is made 



of 

 attached to the seeds 



reach Europe till 1869, when it was found dual nature of the mycopl 



in Spain. In 1872 it reached France, and manifest by the separation of the fungal 



in the next year began to spread more 



rapidly, being 



dinary 



found in at least eight form of growth of fungi. From these 



departments of France, in six counties of threads the pustules arise. Eriksson's are 

 England, and in two localities in Germany, theory as to the origin of the rusts of 

 In 1874 it appeared in Belgium, Holland, cereals was found difficulty of acceptance 

 Denmark, and Italy, and became more by botanists generally, since the corn- 

 widely spread in the countries it had plete merging of the living material of two 

 already invaded. In 1875 it reached distinct plants has no analogy in the 

 Ireland and Switzerland, in the next few animal or vegetable kingdoms. 

 years Austria-Hungary and Greece, but it In the case of Hollyhock Rust, most 

 did not reach Sweden till 1882, nor gardeners hold that seeds from a 

 Finland till 1890. 



spring. 



The same worker has also shown tnax 

 pustules of spores are to be found 



Such seeds gave, 



however, seedlings in which the seed- 

 leaves showed spots of rusts 14 days only 



These results in whicft 



certainly concerned 



rith those of 

 seedlings 



The ravages of jhe disease were very 

 serious at the time of its first appearance, 

 so that as early as 1874 it caused in France 

 an increase in the pr ; ce of Mallow flowers 

 used for pharmaceutical purposes, and for 

 many years it rendered the cultivation of 

 Hollyhocks very difficult. At present the 



" rusted " plant in some way carry 

 the disease so that the offspring develop 

 the pustules even in the absence of in- 

 fection from other plants. Eriksson, as 

 a result of his studies, holds strongly to 

 this view. He made experiments, lasting 

 over several years, with a large num- 

 ber of seedlings from " rusted IJ plants, 



after sowing 

 outside infection is 



in striking contrast w 

 Eriksson, who found that 

 usually remained free from the disease 

 for the first three months when preserved 

 from obvious outside infection. 



Further investigation is necessary before 

 this difference can be explained on tn 

 basis of an hypothesis so improbable * 

 that involved in the conception of W* 

 plasm. 



r It would also be interesting to 



have exact information for this countr * ed . 

 the first appearance of the disease in 

 lings exposed to infection in the °P en reeQ . 

 protected from infection in the g ^ 

 house. As the spores may be attacn 

 the seed, treatment with formalin d 

 sowing would be advisable. 







