340 THE YEAR-BOOK OF AGRICULTURE. 



The Oidium Tuckeri, or Grape Malady of Europe. 



From b paper read before the Royal Institution of Great Britain, by If. Brookedon, wt 



wing information respecting the singular disease which has of late years proved 

 to destructive to grapes of France and other parts of Europe: — 



It appears to have been first observed in England by an observant gardener of Margate, 

 whose oame has been given to the fungus producing the disease — viz. Oidium Tuckeri. It is 

 an egg-shaped fungus, one of an immense family of this class of destroyers, bat one not be- 



known or recognised; and though it bears a close resemblance to those which are found 

 11 j ... 1 1 the potatoe, peach, cucumber, &o., yet it is distinguished from all others by a micro- 

 scopic observer, and has never yet been found upon any other plant, and, when found upon 

 tlu' grape, lias always been destructive. Its first appearance is like a whitish mildew, showing 

 Itself principally upon the young grape when about the size of a pea. 'When the spore of 

 this fungus has settled on the young berry, it enlarges and radiates irregularly in tine fila- 

 ments, which often cover the whole surface, extending with great rapidity. These fix thcni- 

 . s by imperceptible attachments, which do not appear to penetrate the cuticle ; numerous 

 branches from the mycelium are unfruitful; others are jointed, and rise vertically like the 

 pile • : the upper joint enlarges, rounds itself into an elliptical form, ripen-, separatee, 



and is carried off with the slightest motion of the air, to find another grape upon which it can 

 be developed. Warmth and moisture favor its rapid fructification; a succession of spores 



from the same branch, and often two, three, or four ripen and disperse almoBt at the 

 same time. Its effect upon the grape is to exhaust the juices of the cuticle, which ceases to 

 expand with the pulp of the fruit; it then bursts, dries up, and is utterly destroyed. This 

 fatal disease has returned with increased virulence in each succeeding year. In 1847 the 

 spores of this Oidium readied France, and was found in the forcing-houses of Versailles and 

 other places near Paris; but the disease soon reached the trellised vines, and destroyed the 

 grapes out of doors in the neighborhood, and continued to extend from place to place; but 

 until 1860 it was chiefly observed in vineries, which lost from this cause, season after season, 

 the whole of their crops. Unhappily, in 1861, it was found to have extended to tin' south and 

 south-east of France and Italy, and the grapes were so affected that they either decayed, or 

 the wine made from them was detestable. In 1852, the Oidium Tuckeri reappeared in France 

 with increased and fatal i it crossed the Mediterranean to Algeria, has shown itself in 



Syria and Asia .Minor, attacked the Musoal grapes at Malaga, injured the vines iii the Balearic 



ads, utterly destroyed tin- vintage in Madeira, greatly injured it iii the i" ads, and 



d< Itroyed the currants in Zante and Cephalonia, rendering them almost unfit for use; and so 

 diminished the supply, that five hundred gatherers did the ordinary work of eight thousand I 



it i- in France that it- frightful ravages are chiefly to he regarded U a national calamity, 



where the produce of the soil in wine is said to exceed five hundred millions of hectolita 

 two-fifth- of the usual quantity of wine made there has been i, and what has been 



1- bad. It ha- not touched with equal severity all the departments. 

 M. Mdhl ha- most carefully examined whether the Outturn of the grape lives on othtr plants 

 le- the vim-, but he i- deeidedly of opinion that it docs not. Some persons have supp 

 that it was caused by insects', becaui tcasionally the} have been found on diseased \ii 



but the ides il now utterly rejected, for not the -li-hte-t appearance of disease preci des the 



fungus, which creeps over the epidermis, but doe- n. .t enter It envelops the grape, 



il.- the juices of the supeihcial cell-, and stops the growth of the cuticle. The pulp 



nd- within the fruit, bursts longitudinally, its jui< lost, and it chics up. In an 



early Stage of tie e the FangUB may be wiped oil, and the fruit will come to maturity. 



turn never matures on decayed vegetable substances; it lives and fructifies only on 



\\\ in By many it is Baked, I- the Oidium the cau-c, or the OOnsequenoe "i ti.i 



the vine. The vine, one party sa_\-. i- over-cultivated and liable to affections which 



the wild healthy plant re-i t . an I it should be treated a- in a state of plethora : tap it. lessen 

 sap, and it will invigorate so as to resist the poison of the Oidium. Thi- has been tried 



and hai fnled. If I t could not have so suddenly and widely ex- 



tended itself. 



