April i, 1885.] 



THE TR0Pt(5At " XGRfCTTLTURTST. 



761 



the spore before gaining access to the hypodermal tissues. 

 A proper temperature, varying with the species, is essential 

 for this process, but still more marked are the conditions 

 respecting moisture. A fungus spore can no more germinate 

 without water than can a seed of a flowering plant, though 

 neither requires to be immersed in water. Damp air, such 

 especially as we have during fogs, favours the germination 

 and penetration of fungi. Sometimes these processes take 

 place on leaves and fruit when more or less covered with 

 little drops of dew. In bagging Grapes, should any of the 

 rot-spores be included it is by no means probable that they 

 would germinate on account of the want of water, and 

 this is the secret af Grapes so often escaping the disease 

 when the Vines are protected by being trained under the 

 eaves of a building or similar shelter. This influence of 

 water upon germination is one of the important reasons 

 why most parasitic fungi make worse depredations during 

 wet than during dry weather. In most cases the spores 

 themselves are more readily and widely distributed when dry. 



KIND OF INJURY. 



The diseases caused by fungi present many peculiarities 

 according to the species of parasite or of host. Sometimes 

 the latter is simply enfeebled, grows slowly and slenderly 

 as from want of sufficient nourishment, which doubtless 

 is the fact, because robbed. On the other hand, the in- 

 fested parts sometimes take on abnormal shape or size, 

 the cells of the tissue swell to many times their proper 

 dimensions, or become excessively multiplied, or excessively 

 filled with nutrient material. Their normal functions are 

 impaired or diverted, and curious deformations and trans- 

 formations occur. Not unfrequently the abnormal growth, 

 though very different from the healthy structure, is just 

 as regular and characteristic, so that one who becomes 

 acquainted with the peculiar development may be able to tell 

 at once what species of parasite produced the odd cell- 

 formation without seeing the fungus, just as certain galls 

 on plants poiut unmistakeable to the species of insect 

 which caused them.. 



This, or these, modifications of growth seem to be quite 

 as injurious in many instances as the actual robbery of 

 nutriment first mentioned; stems are swollen and knotted, 

 leaves curled and distorted, fruit made unsightly worth- 

 less. But the worst effect of fungi is the more or less 

 immediate death of the invaded cells. In well-known 

 instances this takes place as regularly as the foregoing. 

 certain destruction following the penetration of the my- 

 celium, and affecting the rest of the plant or not, accord- 

 ing to the location of the injury — if on the footstalk of 

 a leaf, that leaf perishes, if at the base of the stem the 

 whole plant succumbs. Sometimes a fungus seems to be 

 so caustic in its effects that by merely creeping over the 

 surface, sending down here and there, however, branchlcts 

 which without entering the epidermis act as suckers, the 

 tissues beneath are destroyed. 



REMEDIES. 



It will be seen from the foregoing that there is much 

 diversity in the physiology of fungi. A full account of the 

 differences known in structure and habit would require 

 a much fuller presentation of the subject than is possible 

 here; but enough has been said to indicate, at least, 

 that there can be no one method of fighting these invisible 

 foes. The unfortunate thing really is. that with all the 

 information yet attained, there is so little r.f practical 

 value in the way of fighting them, after any methods. 

 We can at least, however, understand many tilings which 

 need not be done, and so save unnecessary expense and 

 labour, just as the study of entomology saves men from 

 stringing sweetened corn cobs and hanging them in trees 

 to catch curculios. It is whim-deal and futile to attempt 

 any kind of medication of a plant by incorporating 

 materials in the soil about the roc's. Such applied sub- 

 stances will not usually be absorbed to any considerable 

 extent unless, indeed, directly useful to the plant, ami it 

 may lie safely said that no fungus parasite can be banished 

 or even excluded by the presence in the tissues of any 

 chemical substance thus absorbed, acting as a, medicine. 

 Ami the same may be said of any attempts at medication 

 by directly introducing into the tissues by boring bobs 

 or otherwise, auy substances whatever. The driving of 

 nails, &c., into trees for such purposes is au admittance 

 of iguorauce. or it is quackery. In all this I do by no 



9fi 



means assert that soil elements in certain cases cannot 

 be added which may prevent or reduce the ravages of 

 fungi ; but, if so, these elements must be such as act 

 bv giving special thrift and quality of growth rather 

 than as medicines. 



"We may understand, too, that nothing can be accom- 

 plished out of doors by fumigations or loading the air 

 with strong odours. The impossibility of retaining eveu 

 sulpher fumes sufficiently concentrated in the open air 

 about plants to kill them should teach us that we cannot 

 thus destroy au organism having so little dependence on 

 pure air as a fungus. It is emphatically the exception, 

 not the rule, that under suitable cover auy such method of 

 doctoring these diseases can be practised with profit. 

 How hopeless, then, the case out of doors! So, too, it 

 is usually useless to apply powdered substances to the 

 affected plants in the hopes of ridding them of these 

 parasites. Those who advise others from pretended know- 

 ledge still advocate in hooks and papers the application 

 of flowers of sulphur to Grape Vines in our country to 

 prevent or cure the "mildew" and "rot." Hoiv many 

 tons of sulphur have been thus wasted! There is indeed 

 one species of fungus (uncinuld), sometimes found on 

 American Vines, which can be reduced in this manner ; 

 but it, at least in the "West, is of little moment compar- 

 ed with auy one of the three others that is not in the 

 least inconvenienced by the sulphur as applied. In Europe 

 this sulphuring has been found beneficial, but against the 

 recently introduced American mildew (Peronospora ) they 

 have already discovered the antidote ineffectual. It is 

 surely time that writers in our country should begin to 

 understand that a successful remedy for one thing in 

 Europe may not prove useful for another thing in the 

 United States. The application of washes containing in- 

 [ gredients inimical to fungi has in some cases more effect, 

 and when the special work to be done is understood 

 positive good may follow. But even in this, too much 

 dependence must not be, placed for general use. Such 

 washes are only applicable to the trunks and larger 

 limbs of trees, aud owing to the increase in diameter of 

 the stem cracks soon occur in any such coating, after 

 which the exposure is nearly as great as before. 



Without further criticisms of such methods of prevention 

 or cure, it may be stated that something can still tx 

 offered for special cases; but the prescriptions cannot be 

 made general. In the first place, much in the way of 

 prevention can be accomplished, has already been accom- 

 plished, by selecting varieties for culture which are not 

 subject to the. despoliations of injurious fungi. The orange 

 rust (on the leaves) is very destructive to the Kittatinny 

 Blackberry, but, does not appear on the Snyder; the 

 White Doyenne Pear is very often caused to crack and 

 thus become useless by a fungus (Fusicladium) which often 

 grows to some extent on certain other varieties without 

 injuring the fruit in the least. Such illustrations are very 

 numerous, and when observers learn carefully to discrim- 

 inate different diseases they will rapidly increase. 

 Season of growth, soil, and methods of cultivation and 

 fertilisation may be usefully studied for the purpose now 

 in view. It is not always the least vigorous plants, as so 

 often asserted, that are most liable to rust, mildew, &i 

 Sometimes it is directly the opposite, as in the case of 

 Wheat grown on land which is too rich. Certainly we 

 must not suppose the plants need be in thirftless con- 

 dition before fungi can grow upon or within them. 

 There is simply some condition more favourable than 

 others for the injurious development of the parasite. 

 This special condition it is our business as skilful cultiv- 

 ators to find out. 



There are some special methods of treatment, toe. by 

 which success may be gained. One kind of Wheat smut 

 (Tilletia) can be effectually prevented by washing the 

 seed with a solution of copper sulphate (blue vitriol) ; 

 j but this treatment for the rust on the straw is like 

 smoking cigars to cure corns on the feet. The rust has 

 nothing to do with the seed, but comes from spores 

 passing the winter in the fields. Bagging Grape bunches 

 and growing the Vines under shelter has already been 

 referred to. Washing the trunks and larger branches of 

 Apple and Pear trees with strong alkaline solutions, 

 makes the bark smooth aud much less liable to injur} 

 by what is improperly called sun scald. The fact is the 



