THE GRAPE VINE. 



637 



principal to which it is liable may be considered 

 debility, brought on by bleeding, occasioned by 

 late spring-pruning, the remedies for which 

 have been noticed at p. 631 ; derangement in the 

 circulation of the sap in spring, occasioned by 

 severe frost succeeding warm weather ; and the 

 occasional loss of its young shoots in spring 

 arising from a similar cause. The most fatal, 

 however, of all is mildew, which, to some ex- 

 tent, in certain places, has been observed for 

 years ; nor was much attention paid to it until 

 within these few years, when mildew of a most 

 virulent description made its appearance, and 

 has been determined to be a distinct fungus 

 from Srysiphe communis Dec, or common mil- 

 dew, which probably was that to which we have 

 referred. The new mildew has been denomi- 

 nated Oidium Tucheri. The devastation it has 

 already made in Madeira, and indeed most wine- 

 producing countries, is too well known to re- 

 quire any notice here. It is enough to say that 

 it has established itself in the grape-houses of 

 many parts of Britain. Its appearance, charac- 

 ter, habits, &c., are apparently as mysterious as 

 those of the potato disease, and, like it, it has 

 caused no small consternation amongst horti- 

 culturists. Mr Harris, in an interesting pam- 

 phlet lately published, describes the attack 

 of the Oidium as follows : " The grapes, when 

 blighted (attacked), are covered with what 

 appears to be a white powder like lime, a little 

 darkened with brown and yellow. These fungi 

 send forth laterally, in all directions, thread-like 

 filaments, which become so completely inter- 

 woven with one another as entirely to cover and 

 enclose the skin of the grape in a compact and 

 firm network, and on each are seen the egg- 

 shaped capsule or seed-pod. The pips and juice 

 go on swelling, and at times, when struck late in 

 the season, the grapes become partially ripe and 

 coloured ; but very soon expansion from vrithin 

 going on, checked with this network, the grape 

 bursts; but as it cannot burst as it should do 

 were it uncoufined, the edges of the part where 

 it bursts turn inward in place of outward, and 

 the pips are exposed to view as the teeth of a 

 man when the lips are drawn back. If the 

 grapes are attacked in an early stage of their 

 growth, they dry up, fall off, and become very 

 offensive, but do not split." 



Various remedies have been proposed, the 

 basis of all of them being sulphur ; indeed, 

 that mineral in fine powder has been em- 

 ployed successfully by blowing it over and 

 through amongst the berries by means of a sul- 

 phurator, commencing the application as soon 

 as the disease makes its appearance ; and many 

 wisely do so even before it has time to manifest 

 itself. Dr Price has recently, in "The Chemical 

 Gazette," proposed, as even a more effectual and 

 at. the same time more durable remedy, penta- 

 sulphide of calcium, having observed the effects 

 of the disease in three vineries at Margate, in 

 Kent, near to where it first appeared in England, 

 these houses " having been for five consecutive 

 years infested with the disease ; and notwith- 

 standing the employment of sulphur as flour of 

 sulphur, no abatement of its ravages could be 

 detected. I was," he says, "induced to em- 

 VOL. II. 



ploy a solution of "pentasnlphide of calcium, a 

 diluted solution of which, having been found in 

 no way to act injuriously to the young and 

 delicate shoots of several plants, was applied to 

 the vines ; the object in view being that the 

 pentasulphide should be decomposed by car- 

 bonic acid, and that four atoms of sulphur, 

 together with the carbonate of lime formed, 

 should be deposited in a uniform and durable 

 covering on the stems and branches of the vines 

 affected. Although but few applications were 

 made, the stems became coated with a protective 

 deposit of sulphur, and the disease gradually 

 but effectually disappeared, insomuch that the 

 houses have been, and now are, entirely free 

 from any disease or symptoms of infection. The 

 young wood is in no way affected by its applica- 

 tion ; the vines operated upon were in 1851 

 covered with the disease, but since the autumn 

 of 1852 they have received no further treat- 

 ment. The vines in the immediate neighbour- 

 hood, and adjoining one of the houses, are 

 covered with the disease ; but notwithstanding 

 their close proximity, no indication of the dis- 

 ease has at present been detected in any of the 

 three houses." The following directions are 

 given for its preparation, but in most cases we 

 would suggest to put the matter into the hands 

 of a chemist to insure success ; and this the 

 more so, as its preparation is not a costly affair. 

 Boil thirty parts by weight of caustic lime, with 

 eighty parts by weight of flour of sulphur, sus- 

 pended in a sufficient quantity of water; heat is 

 applied until the solution has acquired a dark- 

 red colour, and the excess of sulphur ceases to 

 dissolve. The clear solution is drawn off, and, 

 after being diluted with water, may be applied 

 to the vines by means of either a sponge, brush, 

 or syringe. A saturated solution of pentasul- 

 phide of calcium may be diluted with from 

 twelve to twenty times its volume of water 

 previous to its being employed. 



The Thrips (Thrips adonidum), fig. 21, and 

 Tkrips ochraceus, both described p. 76, are often- 

 times very destructive to the vine, attacking the 

 foliage particularly in its young state. And 

 next to them is the family of Acarus, or red- 

 spider, of which the following are found in 

 vineries and hothouses, but by casual observers 

 confoimded as the same : — 



Acarus telarim Linn., fig. 22, the common 

 red-spider, or garden-mite. 



Icarus holosericeus, another species nearly as 

 destructive as the last. It is, however, more 

 readily detected than the last on account of its 

 bright vermilion colour. 



Acarus geniculaius is leas destructive in the 

 vinery than the others, but is often found in- 

 festing the bark of the plum and other fruit 

 trees during spring. They present themselves 

 congregated in great numbers at the base of 

 the spurs and small branches, resembling a 

 gummy exudation. They are also exceed- 

 ingly minute, and of a brownish-red shining 

 colour. The appearance of both Thrips and 

 Acarus in vineries, as well as in all other plant- 

 houses, is indicative of toohigha temperature and 

 too dry an atmosphere — conditions which bring 

 these greatest of pests speedily into existence. 



4 M 



