69 



MILDEW OF THE VINE. (OIDIUM TUCKESI.) 



In all ages there have been prevalent parasitic cryptogams, or fangi under this 

 general name, that have drawn their sustenance from the foliage or herbaceous portions 

 of plants and trees, and also from their branches, when in their tender, growing state, 

 and covered with an epidermis. 



The parts of these plants that perform the seminal functions are extremely light, 

 and, under circumstances favorable to their dissemination, are carried in the air, and 

 lodge upon vegetation during growth, and under certain conditions generate and grow, 

 to the detriment, and sometimes destruction of the plants which afford their hahiiat. 



The circumstances and conditions most favorable to the growth of these para- 

 sites, are not such as are most favorable to healthy vegetation, and they take root 

 chiefly, if not entirely, in structures that have been enfeebled by some cause first, and 

 then subjected to the circumstances that are at the same time favorable to the growth 

 of the fungi, and unflivorable to the prosperity of the plants, A course of extremely 

 active vegetation, followed by a cold period, and especially when attended by dark 

 fogs, is always to be regarded with apprehension for the safety of certain plants. 

 Yines are sometimes slightly attacked in early summer, but generally suffer the most 

 serious damage after the fruit is more than half grown. 



From time immemorial European vines have suff^n^ed from the Erineum^ though 

 not to such an extent that much destruction or loss was feared from it ; but in the 

 year 1845 a new Oidium appeared in a vinery near Margate, England, of which a 

 gardener by the name of Tucker had charge, and by whom it was first brought 

 to notice. 



It spread rapidly through the houses of Europe, and from them to the vineyards, 

 until most of the vine districts were overspread with the desolation. It was uni- 

 versally accepted as a public calamity, and the need of a remedy was felt to be of the 

 utmost importance. Yery large prizes were offered for the discovery of one that 

 would be easy of application and efficacious. 



The most important premiums were awarded to Mr. Mares, who showed, by an 

 extended series of experiments, the efficacy of sulphur, and invented convenient appa- 

 ratus for its application. 



For obtaining the full benefits of its action, it was found that three applications 

 were required during the season, at periods diffi'ring according to locality and earli- 

 ness, but ranging from the tenth to the last of May for the first, the same in June for 

 the second, and the same in July for the third. 



The application in July is generally found to be unnecessarj' if the others have 

 b3en thoroughly made at the proper time, and under the right conditions. 



It is not called for in spring, until some well-developed leaves have been formed ; 

 but the first appearance of the mildew should be carefully looked for, and the remedy 

 applied at the slightest indication of its coming, and better if before any manifestation of 

 it takes place, if the leaves are sufficiently developed. 



The subject has deeply interested many of the most careful and scientific obser- 

 vers for nearly twenty years, and is too extensive for discussion here, but the practical 

 results, so far as utility is concerned, can be stated in a brief space. 



This mildew (Oidium Tuckeri) is confined in its attacks to the vine chiefly, if not 

 solely, and it only germinates on the vine when predisposed to it by some enfeebling 

 cause, which acts superficial!}'' upon the leaves, affecting chiefly the epidermis, soften^ 

 ing and impairing its structure. 



The predisposing causes are every thing in the management of the vine, by which 

 it falls short of its most perfectly healthful and enduring development. 



This statement is very comprehensive, and for its full detail, courses over the 

 whole subject of viticulture, but a few of the principal points may be mentioned to 

 make the case more intelligible. General want of drainage, soil so unfertile as to afford 

 scanty nourishment, or so highly enriched as to give distended but not enduring 



