364 



THE GARDENERS' MAGAZINE. 



May 4, 1912. 



STREAK DISEASE IN SWEET 



PEAS.— IL 



I have noticed pathologists and expert 

 advisers recommend a change of ground for 

 sweet peas. I think, however, when this 

 cause is adopted, growers should inoculate 

 the fresh ground, the seed, or plants, with 

 the nitrogen-gathering bacteria, by mix- 

 ing some portion of soil in which sweet 

 peas have been grown with the fresh land 

 to be cropped^ small quantities of old soil 

 only being necessary, say, a handful or 

 less to the square yard, as such soil will 

 be full of beneficial bacteria, or, if pre- 

 ferred, a sweet pea plant having nodules 

 containing active bacteria may be selected, 

 and the nodules may be crushed, and mixe<l 

 with water, and applied with a little soil 

 to the ground. This would bo found to be 

 efficacious. The nodules chosen should ap- 

 pear of a pinkish colour when crushed, and 

 a sufficiency of bacteria may be taken from 

 one plant to inoculate a whole garden. 



When newly broken-up land, or land upon 

 which sweet peas have not previously been 

 grown J is to l^e used, inoculation of the soil 

 is most important. The operation is so 

 easy that it should not be neglected. 



On tho other hand, I find sweet peas 

 succeed remarkably well when grown on 

 the same land year after year, provided 

 the correct system of manuring is adhered 

 to. I have grown sweet peas six years' suc- 

 cessively on the same ground without appa- 

 rent detriment. 



So much is heard about manuring of 

 sweet peas that one is apt to attach too 

 much importance to the subject, because, 

 provided the soil contains a sufficiency of 

 mineral manure (potash, phosphates, etc.) 

 it matters not whether these were applied 

 this year, last year, or the year before. 



An overabundance will do no harm, a 

 deficiency only of any mineral constituent 

 determines the resulting crop. 



I know from practical experience that 

 when sweet peas and other legumes are 

 grown exclusively with the aid of mineral 

 fertilisers the crops are not affected with 

 "streak/' or anv other diseases: even 

 mildew fimgus seldom does harm to plants 

 in soil in which there is ample content of 

 available potash . 



Writing in the Journal" of the Royal 

 Horticultural Society, Mr. F. J. Chitten- 

 den says: " ifie doubts the efficacy of soil 

 sterilisation by heating in connection with 

 sweet peas, as it would prevent the forma- 

 tion of nodules upon their roots, and he, 

 therefore, recommends as an alternative 

 a thorough soaking of the soil with a solu- 

 tion of one part of formalin to two hundred 

 parts of water, to be applied at least three 

 weeks before the plants are put out or sow- 

 ing of the seeds." 



I have had several years' experience of 

 growing sweet pea seedlings in soil par- 

 tially sterilised by heat, and have always 

 found the nodules form naturally and 

 freely in soil which has been heated to 

 212F. Dr. E. J. Russell and other scientists 

 have inspected my sweet pea seedlings grow- 

 ing in such heated soil, and have noted the 

 rodule formation. 



Theoretically^ no doubt, one might ex- 

 pect nitrogen-gathering bacteria to be 

 destroyed by such heating, but apparently 

 they survive, as do spore-producing soil 

 bacteria, or inoculation takes place through 

 the media of w^ater or air. 



It is admitted that volatile antiseptics, 

 such as formalin, for partial sterilisation of 

 soil are not so effective as the heating pro- 

 cess, as none of these completely destroy 

 the harmful bacteria (protozoa and 

 amoeba), whilst neither the antiseptic or 

 heating process completely destroys the 



beneficial spore-producing organism. It 

 therefore follows no special advantage is to 

 be expected by using formalin ; rather the 



reverse. 



A point worthy of note is that when 

 examining a ''streaky plant," if nodules 

 are formed upon roots they contain dead 

 and inactive bacteria, although each nodule 

 may contain countless millions of these 

 bacteria. 



I feel inclined to think that three-fourths 

 of the destruction to sweet pea plants dur- 

 ing recent years has not been due to 

 streak disease, but has been the effect of 

 over-manuring, or feeding, as it is com- 

 monly called, 



I am quite prepared to hear some suffer- 

 ing enthusiast say, ''I did not feed my 

 plants at all," which means the plants 

 died before the contents of the tub of " old 

 stingo " had been used, or before the con- 

 coction to be made from the infallible 

 chemical formula had even been prepared. 

 Quite so ! But what about the tremendous 

 amount of animal manure, etc., deposited 

 in the soil montlis before the peas 

 were planted ? Possibly the roots may have 

 come into contact with this, resulting in 

 the usual consequences-^retarded growth, 

 puckered leaves, distorted or discoloured 

 flowers, shortened internodes, and destroyed 

 root hairs, ending the probable sickening 

 and death of the whole plant, in a way 

 best known to the grower. 



Marshall Ward has said: The time is 

 rapidly approaching when the farmer, or 

 the gardener^ will as little dare to neglect 

 the study of ' physiology and pathology of 

 plants, as the surgeon dare practise with- 

 out a knowledge of anatomy, or the sailor 

 hope to become a captain without studying 

 navigation." 



I believe the cultivator of the soil will 

 soon recognise the necessity of becoming 

 acquainted with the life history of the 

 tiny organisms w^hich exist therein. The 

 knowledge of the existence of the various 

 groups, and of their mutual relations, will 

 most certainly tend to the more careful and 

 economic use both of the farmyard manure 

 and of artificial fertilisers. 



E. W. Duckwall, in Bacteriological 

 Technique/' says : 'Teas grow well in chalky 

 and other calcareous soils, but a fine growth 

 depends almost entirely upon the presence 

 of nitrogen-fixing bacteria, and it is pos- 

 sible to prepare the conditions artificially. 

 AVhen peas are planted in a soil containing 

 all the elements for growth excepting nitro- 

 gen, they will thrive well if there are any 

 nitrogen-fixing bacteria present, because 

 these little workers will build up the 

 nitrates for the plants, but if none of 

 these are present the growth is poor, . . . 

 the plants will cease growing, the leaves 

 turning yellow, and there is no disposition 

 to bear pods. The plants in this case are 

 suffering from what is termed nitrogen 

 hunger, when, at this stage, if the soil near 

 the roots be moistened with water contain- 

 ing nitrogen-fixing bacteria, wonderful 

 changes will be noticed in a short time. 

 The stem and branches will grow stronger, 

 the leavos will turn green, and the pods 

 will fill with peas rapidly." 



In the face of such evidence <h it to be 

 wondered if the reversal of such a com- 

 plicated provision of Nature should be 

 visited with such dire consequences when 

 nitrogen is supplied in alien form. 



Robert iBoLMEs. 

 Tuckswood Farm. Old Lakenham. 



enormous 

 trees. 



For pretty gardenia and lovely flowers read The 

 Flower Gakden. by T. W. Sandera, F.L.S, An ui> 

 to-date work on the formation, planting-, aad manage- 

 ment of the garden, with description and cultivation 

 of flowere. and plants adapted for outdoor culture. 

 Price, 7e. M. net by poet, in ™m W. H. 



and L. Colling-ridge, 14H and U9, Alderegate Street, 



Locdon. 



THE FORESTS OF NORTH 



AMERICA. 



In a lectuxe delivered recently before the 

 Aberdeen branch of the Royal Scottish 

 Arboricultural Society, Dr. Somerville said: 

 In North America not only was there a 

 variety of climate^ 'but concurrently an 



variety of vegetation, including 

 From an economic point of view the 

 forests of North America were of the very 

 hrst importance, and the United States con- 

 stituted the most important of the timber 

 exporting countries of the world. That 

 country exported annually something like 

 ^18,000,000 to ^620,000,000" worth of timber. 

 The country the States drew upon most 

 liberally for the ordinary class of timber was 

 Canada. From facts submitted recently to 

 the Caniidian Government, the United States 

 at the present time were consuming some- 

 thing like two-fifths of all the pulp-wood for 

 manufacture into paper m United States 

 mille. The Canadian Government was, how. 

 ever, extremely anxious to stop the exporta- 

 tion of raw pulpwood to the United States, 

 and New Brunswick, Quebec, Ontario, and 

 most of the important timber provinces of 

 Canada had been passing Acts to prevent ex- 

 portation of pulp-wood in the raw condition 

 to the States, 



Dr. Somerville proceeded, by means of 

 maps, photographic slides of interesting 

 parts of wooded country, of special forests, 

 and of giant individual trees, to describe his 

 visits to the United States and Canada. He 

 described the great forests of spruce he found 

 in New Brunswick. Exactly how much 

 timber there was in Labrador could not be 

 known, because as yet that province wa« 

 largely unexplored. It was, however, from 

 Labrador that large quantities of timber 

 came which could be used for pulp for the 

 manufacture of paper. Great hopes had been 

 entertained that when the Canadian Northern 

 Railroad, at present under construction, was 

 ope-ned, that great quantities of timber 

 would be available in vast extents of forests. 

 That hope, however, had not proved to be 

 realised, because the surveyors who had been 

 along the line of route reported that the 

 country there was so poorly wooded that it 

 could do no more than supply the construc- 

 tional material required for the railway. 



West of Lake Superior they got into the 

 prairies, stretching away towards and beyond 

 Winni]>eg, where they had only scrub poplar 

 and larch, and Banks's pine. Further west, 

 in the purely prairie country, they found wil- 

 lows and poplars growing alongside the 

 banks of the rivers. When they approached 

 the Rocky Mountains they got a forest coun- 

 try extending ^uth of the Selkirk range, and 

 there they had several of the most magnin- 

 cent of the American forests. It was in that 

 district that many of the wonderful trees 

 were found indigenous — the Sitka spruce, the 

 Douglas fir, the Grandis pine, the Picea 

 nobilis, and the Lawsoni fir. In the valley 

 of the Mississippi they had many of the hard- 

 wood trees — chestnut, birch, cherry, ana 

 others at their best in that mountain range. 

 Tennessee, North Carolina, and Virginia 

 were right in the middle of that great hard- 

 wood forest area, in which very little cut- 

 ting had been done. By means of a series 

 of beautiful illustrations. Dr. Somerville 

 gave his hearers a capital idea of all tne 

 various features he had referred to. 



The lecturer then dealt with the char^- 

 teristic trees of Eastern Canada, and show'W 

 what the Canadian Government were doinP 

 on the prairies to afforest the bare lands 

 there and give protection to crofts and home- 

 steads. That Government distributed Y^^^^ 

 plant-s free of charge to settlers, and tlie 

 distributions were made from nurseries at 

 Indianhead, Alberta. The work was etartea 

 in 1905, and by slides the lecturer showea 

 how well the trees grew up in a matter o 

 four years' time on an area that was pr*^" 

 viously treeless. It was interesting to know 

 that trees doing best in the re-afforestation 

 of the Canadian prairies were the trees com- 

 monest in Great Britain. 



