limit, even in the shade. As the oïdium does not propagate itself nor develop rapidly until the temperature reaches 25° to 35° of Centigrade (77° to 95° of Fahrenheit), such a heat insures the action of the sulphur against every increase of the disease. When the temperature is too low, the sulphur does not sensibly act; and if blown off by wind or washed off by rain, it must be applied anew. The action of the sulphur on the oïdium is quick enough, but it does not become apparent until after a few days.

When the sun strikes the diseased parts which have been covered with sulphur, the action is much more energetic and rapid: it becomes apparent from the second day, and often sooner. This results from the warmth of the sun's rays.

A sulphuring well applied, which reaches the entire surface of the vine, will therefore destroy the oïdium; but, as the vine grows continually, and the grapes enlarge daily, as the wind and the rain carry off all the while some of the sulphur from the surfaces where it was deposited, they soon become bare again and are exposed to new attacks; then the oïdium again appears and attacks the vine, as it did at first. This occurs ordinarily in summer time, after an interval of twenty to twenty-five days,* or some

* When the ground is very damp beneath the surface, and the lat

times a longer one. Then, again, it may happen that the oïdium will not make a second appearance in serious form, especially if the weather continues for a long while very dry and very hot, and the sulphur rests a good while on the ground and on the various parts of the plant.

The high temperature produced by the vertical rays of the sun in summer vaporizes the sulphur in a perceptible manner. It gives out then a very lively odor, which all must remark who have employed it on their vines. It is that portion which falls on the ground without reaching the vines which feels more particularly the effect of the heat and passes into vapor, because the sun's action heats the soil much more than it does the foliage. It results from this that the sulphur which was spilled and seemed lost, produces, on the contrary, the happiest and most continued effects, by passing daily into vapor under influence of the daily sunshine. Its molecules thus penetrate

ter is dried, baked, and covered with weeds, and great heat succeeds to heavy, drying winds, the oïdium will reappear more quickly. In such circumstances I have seen, in 1856, in the month of July, its invasions renewed after only ten days of interval. Such a combination of circumstances is not frequent; at the same time, it will occur in In such cases the sulphurings must be brought closer together, and renewed as often as the invasions are repeated.

wet seasons.

L

numberless points on the foliage and fruit that might not otherwise be reached.

I am sure that it is not at all to the sulphurous acid, nor to the sulphuric acid which is found in small quantities in flour of sulphur, that the action of the last upon the oïdium is due. The same effects may be produced after having washed it; they may also be obtained with sulphur-rolls well pulverized.

[Here follows a very closely detailed examination into the characteristics of the two forms of sulphur, namely, the ground and the sublimated, or flour of sulphur. The chapter devoted to this is omitted, with the observation that flour of sulphur is the best to use in America, as the difference per cent. in price is not here so great as it is in France, and its greater cheapness there is the only advantage it possesses over the other. The flour is very light and fine of texture, and of a beautiful yellow color. Ground sulphur is much the lighter in color, and the finer (and, of course, the better) it is, the lighter is the hue.]

SULPHURING OF DISEASED VINES.

The sulphuring of vines is an operation which consists in spreading over their foliage and fruits sulphur in fine powder.

Flour of sulphur obtained by sublimation is ordinarily the form of it most suitable for the purpose. Three conditions are necessary to insure a good result.

1. The application must be made as soon as the oïdium begins to appear on the vine. Thus the parasite will be prevented from obtaining too strong a foothold on fruit and foliage to impair their vegetation and disease their tissues.

2. The sulphuring must be renewed as often as the oïdium renews its attack, and as soon as it reappears. Thus we continue to operate on the surface of the plant, and to prevent the bad effects which would not otherwise fail to follow a new invasion.

3. The application should be thorough, and reach every infected part. It will not do, therefore, merely to sulphur the diseased fruit; the shoots, leaves, and all the fruit-in a word, every green part, must be dusted with sulphur. When we find a single bud on a stalk to be diseased, we may be sure every other bud carries on its surface the germs of the disease; to destroy those germs, they must be reached with sulphur-dust.

The fundamental principle is this: scatter the subphur on every green part upon the first appearance of the symptoms of the disease, and renew the ap

plication each time it reappears. It is especially at the commencement of vegetation that we must keep the vines free from attack. At that epoch the least delay is dangerous, for the buds then attacked are so young and feeble they have no power of resistance; they emaciate, are stunted, and very quickly lost. Moreover, the earlier the disease appears the more virulent it generally is. The Carignans and Picardans, varieties which are usually the first to be attacked, are examples of this.

A precautionary application may be made before any sign of disease appears. It can do no harm, but there is no rule for prescribing it. Such applications have no other objection than that, if made after vegetation is well advanced, they cost something. In the earlier periods of the development of the buds, that is to say, about the middle of May, the cost would be insignificant. But preventive applications should not be relied on too long, nor lull the vigilance with which we should watch every portion of the vineyard.

Such a surveillance it is easy to organize by dividing the field according to the varieties it contains, and keeping a memorandum of the applications each division has received.

Proprietors who have their vines sulphured should