216 



THE GARDENERS' CHRONICLE. 



[April 6, 1912. 



to construe my remarks in a manner in which 

 they were not intended. While pointing out the 

 difficulties, yet there is every hope of making im- 

 portant discoveries along these lines ; and here 

 again is an opening for the practical fruit-grower 

 to teach a lesson any day to the scientific investi- 

 gator. 



Next, let us consider the resistance of disease. 



In medicine we are informed that living accord- 

 ing to common, normal sense, avoiding foods or 

 practices which lead to the weakening of the 

 organism, we will not only reach but maintain a 

 condition which we describe simply as health. 

 Health, to my mind, is nothing else but the 

 keeping of body and mind sound by performing 

 the normal functions of our organism. Thus, by 

 following closely our needs, and by living cor- 

 rectly, we can bring our bodies into a state of 

 great resistance and even immunity, though we 

 may be living amidst a serious epidemic at the 

 moment. Infectious germs, though surrounding 

 us constantly, will have no chance of exercising 

 their serious effect upon us if we are in a per- 

 fectly sound state of body. It is quite im- 

 possible to avoid contact with disease germs, and, 

 this being the case, prevention of disease is 

 largely dependent upon success in bringing our 

 organism into a strong condition of resistance. 



Now this is exactly the same case in plants. 

 Plants are living beings, subject to all kinds of 

 ills, without being actually diseased, i.e., being 

 attacked by a specific organism bringing about a 

 pathological condition. The late Professor 

 Marshall Ward has expressed himself very in- 

 structively on the subject of predisposition of 

 disease in plants. He refers to two plants of the 

 same kind, as much alike as possible in every 

 respect, size, condition, development, etc., and 

 goes on to say : u Picture to yourself one of these 

 plants growing under the most perfect condi 

 tions, supplied with the proper amount of food, 

 its roots expanding into a well-ventilated soil, 

 rich in humus and plant food, &c, &c, and the 

 other growing under absolutely reverse condi- 

 tions. The result will be, in one 



, a strong, 



healthy plant, and, in the other, a poor, weak- 

 ened plant, just strong enough to keep alive." 

 Now the conditions, not to say constitutions, of 

 these two plants must be very different. Dif 

 ferent modes of nutrition, we know, produce 

 different chemical changes within a living plant. 

 And no doubt this difference in the condition of 

 the host is accountable for its power of re- 

 sistance or state of susceptibility. There may be 

 a number of other factors producing similar dif- 

 ferences in constitution, or in composition, if 

 this is more correct. A Potato tuber, sound and 



fresh, will remain free from fungi if kept in an 

 ordinary room, while one that has been exposed 

 to frost or steam heat for a moment or two will 

 soon be covered with mould fungi of various 

 kinds. We know, of course, that the chemical 

 composition of the Potato exposed to frost or 

 heat is changed, but in addition we have also 

 partly destroyed its life. The same may be said 

 of Professor Ward's " ill-treated " plants. To- 

 gether with the changes of the chemical composi- 

 tion, we have reduced its vital power; hence, 

 would it not be reasonable to expect an increased 

 resistance to disease if the vital power of any liv- 

 ing organism is kept up to the highest mark? 



That this contention is fundamentally correct 

 is amply proved by the fact that cultivated plants 

 which we grow in unaccustomed conditions are, 

 generally speaking, more subject to disease, just 



more liable to disease 



The sudden or even 



as Europeans are 

 in tropical climates, 

 gradual changes frequently result in lowering the 

 vitality of a living organism. Cultivated trees — 

 fruit trees — are constantly subject to such un- 

 natural changes. Hence, if we do not concen- 

 trate all our efforts in providing for them the 

 most favourable conditions for growth, disease 

 is likely to appear. Proper care of the trees 

 should be our foremost, aim, and diseases will then 

 levy a less severe tax upon the fruit-grower. To 

 be most successful in fruit-growing w T ould necessi- 



tate an intimate knowledge of the chemical, 

 mechanical and physical condition of the soil, 

 and to remedy, above all, any deficiencies in this 

 direction. The next step would be to become 

 acquainted with the general principles of protec- 

 tion from diseases and their treatment. 



I have endeavoured to explain in the fore- 

 going remarks, briefly, the life and nature of 

 parasitic fungi. We have considered how fungous 

 diseases are spread by means of the spores 

 produced by the causal organism, we know how 

 different may be their mode of fructification, and 

 that winter and summer spores must be looked 

 for in many kinds. We have further discussed 

 the effect of a fungus on the host plant, and 

 hinted at certain factors rendering plants more or 

 less susceptible to disease. Bearing these points 

 in mind, and knowing the ways and means of 

 attack of our enemies, it is only wise to exercise 

 all tactics to prevent a successful onslaught in our 



orchards. 



First of all, successful work must be begun as 



soon as possible after the harvest, but not before 

 all leaves have fallen to the ground. In order 

 to carry the destruction of hibernating fungi as 

 far as possible, all leaves and bad fruits should 

 be removed from the trees. The practice of 





•"-*"-*- - ---■ 





FlG. 95, — MAP SHOWING THE DISTRIBUTION 

 IN ENGLAND OF THE SMALL-LEAVED ELM, 



ULMUS SATIVA. 



leaving some fruits on the trees is very common, 

 and very dangerous. In the case of Plum poc- 

 kets, brown rot of Peach, Plum and Cherry, this 

 practice provides conditions favourable to the 

 hibernating fungus. Therefore, remove all dead 

 wood and fruits and other rubbish covering the 

 ground. It has been frequently recommended to 

 plough the orchards soon after harvest to bury all 

 dead leaves and fruit, when they will be put out 

 of harm. This would be correct if subsequent cul- 

 tivation in spring did not result in the bring- 

 ing to the surface the matter we desired to 

 destroy. For the burying over winter of fungus 

 spores in soil does not destroy, but rather tends 

 to preserve them in the orchard. It is best be- 

 yond doubt to thoroughly clean the surface of 

 the ground by raking together all rubbish and 

 burning it. If this practice were general we 

 should only have to deal with diseases that come 

 from our less careful neighbours. This recom- 

 mendation may sound very simple, but where 

 the orchard is sown with a cover crop of 

 Clover, Lucerne, or Rape, it is almost im- 

 practicable. Here is another opportunity 

 for growers to test by experiment whether 

 it would be more profitable to get the benefit 



from a cover crop, which may be valuable in 

 itself, or enrich the soil, or protect the roots from 

 frost injury, as some growers claim, or whether 

 it would prove of greater value to keep the 

 ground clean, kill the winter spores of disease, 

 and have an increased revenue from sound fruit. 

 Together with this cleaning operation, there 

 should be practised the scraping of cankers and 

 the trunks of trees showing rough bark, and the 

 painting of the former and any wounds with white 

 lead or any other paint which, does not contain 

 turpentine, for turpentine penetrates into the 

 wood and kills the cambial and other tissues. 



After an orchard has been carefully cleansed, 

 the trees should be sprayed, and lime-sulphur 

 cannot be too highly recommended for this pur- 

 pose. It not only prevents any fungus spore* 

 from starting into life, but is also invaluable as an 

 insecticide. 



In spring, when the days are free from frost, 

 lime sulphur may be sprayed again, followed 

 thereafter w T ith Bordeaux Mixture as soon as the 

 buds begin to swell. 



The expense of labour to carry these suggestions- 

 into effect should not be made responsible for 

 neglect. Recommendations such as I have made 

 can only be of the desired benefit when they are 

 practised universally, and successful fruit-growers 

 should do their utmost to get all others to follow 

 their examples. H. T. Gussow. Dominion 

 Botanist, Ottawa, Canada. 



r 



BRITISH ELMS. 



(Continued from p. 199.) 



The Small-leaved Elm (U. sativa Mill). 



Goodyer's second Elm is designated " Ulmu 

 minor folio angusto scabro." This is much 

 M lesser and lower " than the English Elm. 

 Goodyer observed it " in the hedges by the 

 highway. . . . between Christ Church and 

 Limmington in the New Forest in Hampeshire 

 and here, I may add, it still may be found. 

 Goodyer's description and the specimens of the 

 old English collectors (who attach Goodyer's 

 name to their plants) prove this to be the Small- 

 leaved Elm. It is the U. minor of Parkinson 

 (Theatr. Bot., p. 1405, 1640), the U. campestris 

 var. B. Hudson (FL AnqL, 96, 1762), and the 

 U. sativa of Miller (Gard. Diet., ed. 8, no. 3, 

 1768). Miller cites Goodyer's name, and adds 

 that " as this tree is so well known, it requires 

 no description.' ■ Miller's is the first binomial 

 given to the plant after the publication of 

 Linnseus's Species Plantarum (1753) where 

 modern botanical nomenclature begins; and we 

 are bound, if we follow the international rules 

 of nomenclature and if we regard this Elm as- 

 a species, to accept Miller's name U. sativa for 

 the tree which the early English botanists from 

 Goodyer's time to Miller's, with unvarying con- 

 sistency designated as U. minor folio angusto 

 scabro, as the specimens preserved in the British 



Museum show. 



The tree has received several other binomials ; 

 but all these, being of later date than U. sativa 

 Mill., must lapse into synonymy. The latest 

 name to b* given to it is U. Plotii Druce. 1 

 have seen several specimens of plants so name 

 and issued by Mr. Druce; and all of these are 

 to be referred to the small-leaved Elm (U. sativa 

 Mill.). ; . 



I can well understand Mr. Druce's eulogy <» 



this tree which had almost been consl % ne *i° 

 oblivion by those botanists who attempted tne 

 almost impossible task of describing the > nun ? e 

 ous British Elms under two names; but * ^ 

 Druce's description of it is meagre, and ^ does . 

 real injustice both to the tree itself and to 

 commendable enthusiasm for it. 



This and the Cornish Elm (U. strict*) «£ 

 the last of our Elms to come into flower. As i 

 is written (Feb. 25, 1912) they are the only * 

 near Cambridge whose flowers have not : 



opened. „ 'ti^b* 



As it is not mentioned in any modern b" 



^ 



