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CASSELL'S POPULAE GAEDElrtNG. 



of tlie dust do not get close enough to the mildew, 

 but are carried off or too much diluted. 



But these whitened leaves and shoots are signs 

 of constitutional distress, as well as the \'isihle and 

 sure proofs of a troublesome disease. Like canker, 

 mildew arises from many and the most opposite 

 causes, such as over-feeding, over-cropping, excess of 

 heat or of cold, of drought or moisture, shelter or ex- 

 posure, excess of vital force, or drooping weakness; 

 so that everything that has been advanced about the 

 preventive cure of canker is also applicable to that 

 of mildew. 



A damp situation, with a wet bottom, may be said 

 to generate mildew most rapidly. Nevertheless, a hot 

 burning speU of drought of six weeks' duration wiU 

 also produce it. Hence, in the first case, drain it 

 out; in the second, water it out, would be the best 

 advice. And so in other cases, a permanent cure is 

 hopeless unless one were familiar with all the local 

 and general conditions that caused the disease. But 

 if the precautions against and cures for canker are 

 . carried into practice, any mildew that appears vrill 

 be readily arrested and cured by the local application 

 of lime and sulphur, or either with a little powder of 

 dry soot, as already described. 



American Blight.— This is, as a disease and 

 an insect, of the most terrible sort. Canker, mildew. 

 Aphides, or any check of growth, seems to favour its 

 production. It establishes itseH with augmented de- 

 vouring force around cankered wounds where it exists 

 at all, and combines the evils of rheumatic gout with 

 those of canker. American blight is almost inva- 

 riably accompanied with a sort of granular swellings 

 of the wood and bark, and these seem stiU further to 

 arrest the flow of the sap, and bring or keep more of 

 it in or around the blight colony. The term blight 

 is somewhat misleading, as anything and every- 

 thing that checks growth, induces disease, or causes 

 the flowers or fruit tp drop off is called a bUght. 

 But this so-called American blight is really an in- 

 sect or Aphis; it was thought at one time to be 

 Aphis lanigera, but differing so widely from this 

 destructive famUy as to be distinguished by creation, 

 into the genera of Erioaoma, and as it confines 

 its depredations mainly to the Apple, E. mali, or 

 the "Woolly Aphis, or Apple Bug ; the former being, 

 on the whole, the more expressive name, as the long 

 filamentaceous threads almost wholly cover the in- 

 sects, as well as protect them from the effects of rain. 

 These appendages give the Apple Bug at first very 

 much the appearance of the Mealy Bug of our hot- 

 houses, the Coccus Adonidum, the most troublesome of 

 all pests to such plants as Stephanotis, Gardenias, &c. 

 Unfortunately this troublesome disease and pest 

 does not confine its operations to the tops of trees, 



but also attacks their roots with equally disastrous re- 

 sults Hardly have they fastened on them before they 

 produce the granular sweHings already described, the 

 supply of sap is diverted or cut off, and, instead of 

 being sent to the front about its proper business, the 

 extension of the top-growth, the formation or filhng 

 of fruit-buds, and the nourishment of the fruit, it is 

 too often worse than wasted in the production of 

 quantities of root-suckers, that further impoverish 

 and weaken the tree. Noronlythis; their active inter- 

 ference with function and force are fruitful causes of 

 nuldew and canker. This is so generaUy the case, 

 that it is quite rare to see bad cases of American 

 blight without either or both of the others. Nor 

 does this exhaust the evil effects of the Apple Bug. 

 It violently arrests the sap, modifies its character, 

 and probably augments its sweetness. Be this as 

 it may, and the point has not yet been very clearly 

 established, it is certain that the common Green-fly, 

 or Aphis, and nearly all other pests that attack Apples, 

 are subject to cluster around and multiply with 

 amazing rapidity, upon trees already infested with the 

 Apple Bug. 



It may seem like idle reiteration to assert that all 

 that has been included under the heads of skiUul cul- 

 ture is the surest antidote to this disease, and the 

 best means of eradicating these insects. Apply also 

 the radical cures prescribed for canker and mildew. 

 Still it must be admitted that the Apple Bug is not 

 so frequently the product of mistakes in soil, site, 

 climate, or treatment, as either of the other diseases. 

 It comes suddenly at times on vigorous and healthy 

 trees, and may work sad havoc before it is much ob- 

 served. It not seldom originates in a dry state of the 

 sou, and preys upon the roots before it climbs to the 

 top, and, like the Vine Louse, it works most mischief 

 underground. Fortunately it can be drowned out, 

 and if house sewage or powerful liquid manure can 

 be used for the flooding of the roots, the sooner will 

 our wool-clad foe vanish. It is seldom or never 

 found on roots with much destructive force where the 

 soil is wet, and could a stream of water be made to 

 flow over Apple-roots for twelve, eighteen, or twenty- 

 four hours, there would be an end to most of the 



On the trees one heavy syringing is of little use, 

 unless the water is driven on with sufficient force to 

 strip the insect of its filamentous appendages. They 

 never seem to get over such a real denudation, or to 

 be able to grow fresh whiskers. But there are many 

 liquids that make an end of them by the merest touch. 

 Among these, turpentine, spirits of wine, pure or 

 methylated, any of the mineral oils — benzoline, pa- 

 raffin, and petroleum — are the more efficient, killing 

 instantly where they touch. Weak solutions of 

 carbolic and sulphuric acids also deal death to the 



