two sorts. One of them would attribute the disease to the presence of certain little insects whose stings cause the wounds on which afterward the oïdium develops itself. This system is at this day altogether abandoned, for direct observation has never been able to discover any insects whatever in numbers sufficient to produce effects like those of the dis

ease.

The other opinion attributes the disease of the vine to a particular state of the plant itself. That diseased state of the interior that has been observed might be produced by the appearance of the oïdium, and would then be the effect, and not the cause of the disease. This explanation might be well founded if we knew to what to attribute the diseased state of the interior; but, down to the present time, nothing has occurred to justify the supposition. Vines are diseased in all countries, in all situations and exposures, in the best soils, of every species. Every kind of treatment, by manuring, pruning, cultivation, etc., have failed. We must then give up this explanation, since experience does not confirm it.

The only opinion which, down to the present time, agrees with direct observation, that which attributes the disease to the development of the oïdium at the expense of the various organs of the vine on which

it plants itself, is that which, it appears to me, should

be adopted.

CONDITIONS TO BE FULFILLED IN ORDER TO COMBAT

THE VINE DISEASE.

In placing ourselves at this point of view, the problem of how to combat the vine disease resolves itself into that of destroying the oïdium, or its germs, in all stages of their development, and on every part of the vine where they may be found.

I have made, toward this end, for several years past, a great number of experiments of all kinds, and I have realized that it was hardly possible to destroy the disease by attacking, during the slumber of vegetation, the germs which reproduce it. The means employed for this purpose may accomplish it, and the disease will not disappear for all that.

In effect, as soon as vegetation is in movement, a cloud of reproductive oïdium germs, transported by the currents of air, light upon the green portions, take possession of them, and at the end of a few days the disease breaks out anew; the oïdium grows, fructifies, implants itself every where, destroys the fruit, and emaciates the vine.

The methods which aim at merely curing the diseased grapes are still more insufficient than the pre

ceding, because they leave the disease full sway during the first three months of the vegetation of the vine, the very time when it is most redoubtable, and abandon altogether to its ravages the shoots and leaves. Such methods really amount to very little.

As we can only certainly know the presence of the disease by that of the oïdium, and as it fastens only on the green parts, it is upon those green parts we must attack and destroy it as soon as the parasite begins to make its appearance there.

The conditions to fill are therefore the following: 1. To operate on all the green surfaces of the vine in vegetation, penetrating wherever that fine dust can penetrate which forms the spores of the oïdium.

2. To renew as often as necessary the application of the destructive agent employed against the oïdium, since the means of reproduction it possesses are incessantly at work, and it can develop itself anew as soon as the green surfaces of the vine cease to be protected from its attacks.

3. To apply the remedy before the oïdium has been able to impair the tissues of the different parts of the bud-above all, when it is young. This last condition is the most indispensable, because, if we fail to destroy the parasite until it has more or less affected the parts, we shall obtain but a partial result at best-the evil is already done.

These three conditions should be fulfilled by means that are sure, practical, not too costly, and which do not interfere at all with the divers operations of cultivation.

PROPERTIES OF SULPHUR.

The object is attained in an admirable manner by the flour of sulphur. It possesses, in fact, all the properties necessary to constitute it the curative agent "par excellence." On the one hand, it destroys the oïdium whenever coming in contact with it; and, on the other, its form, being that of a very fine dust, enables it to envelop by a simple aspersion the entire plant in vegetation, and its volatility in the temperature daily produced by the heats of summer on the earth and the green surfaces exposed to the sun insures its action on the mischievous germs. It has, besides, the property, as remarkable as unlooked-for, of stimulating the vegetation of the vine, thus communicating to it vigor to conquer the attacks of the parasite.

Sulphate of lime, soda, potash, which destroy very well the oïdium when they can be brought in contact with it, are not at all volatile like sulphur. They have not at all, as it has, the property of penetrating in the form of vapor all those places left un

touched by it when in the form of dust, and of continually renewing their curative action by every day vaporizing a little. They have, too, the serious inconvenience, if they pass into the wine with the grapes, of imparting to it a bad taste not always to be got rid of.

The mixtures of sulphur and of dust, such as pulverized earths, plaster, etc., have the inconvenience of neutralizing, more or less, the action of the sulphur, so that by using such we risk obtaining but incomplete results. We may, besides, injure the quality of the wine if the mixtures in question are capable of forming soluble combinations in it.

ACTION OF SULPHUR ON THE OÏDIUM.

By direct observation under the microscope, we are able to see that the grains of flour of sulphur cause the oïdium to perish when they enter in contact with it.

One condition seems always necessary, which is, that the temperature should be above 20° of Centigrade (68° of Fahrenheit) when the contact takes place. Now this condition is always filled during days of sunshine, from the time the buds begin to put forth in April and May. Later, during the days of summer, the temperature almost always passes this