b

a

tissue except that it sends down among the cells occasional suckers (see fig. 12, b. b.), by which it draws nourishment. That the threads of the mycelium are not. easily distinguished is evident when we note Prof. Scribner's statement that they are each only one sixthousandth part of an inch in diameter. In June or July short upright branches appear, which are jointed, as shown in Fig. 12. One by one these terminal cells drop off. They are really summer spores for the propagation of the mildew, and are known as conidia. Two of these are shown in fig. 12, a. a., which, according to Prof. Scribner, are only one-thousanth part of an inch in length at their largest diame ter. These float about in the air, and alighting on a proper host soon germinate under the favoring conditions of summer heat and moisture.

grape leaf.

Fig. 13 shows a very small portion of epidermis of a grape berry, upon which the mycelium of Uncinula has grown, highly magnified.

Later on in the season, during the months of September and October, spores quite different in character are formed. The case in which they grow is apparent to the naked eye, and is known as the perithecium, or "fruit" of the mildew. Each of these is full of asci, three of which are shown emerging from the perithecium in fig. 14.

Inside these, in turn, are the ascospores, or winter spores.

These are safely protected during the winter season by the hard compact walls of the perithecium, which in spring crack open and allow the asci to escape, and bring about a new infection of the vines. While this mildew is not nearly so destructive as that variety called the Downy mildew, still it is capable of wholly ruining the crop of certain varieties which are subject to it, as for instance, the Salem.

FIG. 14.-Perithecium of Uncinula Spiralis, with hooked
arms, which give rise to the name uncinula.

The usual remedy found to be quite effectual in most cases in the Niagara district, is dusting flowers of sulphur on the vines, or, in hot weather, underneath them; but a more certain and effectual method is spraying the vines with the Bordeaux mixture, or the carbonate of copper early in the season.

THE POWDERY MILDEW OF THE GOOSEBERRY (Sphærotheca mors uvæ.)-Like the powdery mildew of the grape, this is a parasitic fungus, filamentous or thread-like in growth, and only attacks the surface of the host, giving it a powdery appearance. Gooseberries affected, as everyone knows, are rendered both unsightly and undesirable for food, and it is owing chiefly to the prevalence of

this mildew in Ontario that so few of the superb English varieties are found in our gardens.

It first appears on the young half grown leaves and young wood, and later upon the young berries. Prof. Scribner, in his report on Vegetable Pathology for the year 1887, gives full illustrations and description of this fungus, and to it we refer any one who wishes to carefully examine its growth. Suffice to say here, that its summer spores are formed similarly to those of the powdery mildew of the grape, the upper segments of the conidia dropping off, and being carried about easily by the wind to scatter the evil; and that its winter spores are also formed within perithecia in a similar manner to those of the grape. When these perithecia ripen they become a chestnut color, hence the gooseberry mildew in its last stage loses its white appearance and becomes a dirty brown; and in this way the condition of the mildew may be determined.

Any remedy to be successful must be early applied. Early and frequent applications of flowers of sulphur are useful, but not so effective as in the case of the grape-vine mildew. Experiments at the Geneva Experiment Station, conducted last summer, have resulted in the discovery that the most successful treatment of gooseberry mildew is with sulphuret of potassium. The bushes were sprayed at an early date with a solution of one half ounce of this substance dissolved in a gallon of hot water. It is therefore recommended as the best known remedy for this evil.

CHERRY ROT (Oidium fructigenum) is the most serious obstacle in the way of the successful cultivation of this valuable fruit. The Heart and Bigarreau varieties, and especially the latter, are particularly subject to this fungus. The Napoleon Bigarreau, for instance, is frequently very heavily laden with fruit, but a protracted season of wet weather so encourages the development of this fungus that the rot, beginning in small spots, soon spreads from cherry to cherry, until, before picking time, the whole crop is entirely unfit for shipping. Could we succeed in overcoming this evil, we are of the opinion that the cultivation of the many very excellent varieties of cherries would be more remunerative to the grower than strawberries.

The fungus itself consists of much branched threads, or mycelia, which permeate the tissue of the fruit, causing it to turn brown and decay. When the air is moist these throw up tufts of dirty white dusty fruit stalks. These divide into minute sections

which, when ripe, separate and fall off from the top, one by or.e, in the form of spores. These spores are so light as to be readily carried about in the air from tree to tree, and thus the evil is rapidly spread about through the orchard. Fig. 15 is a representation of two fruiting threads of this fungus before the spores have begun to fall away, magnified 250 diameters. The engraving is reproduced from a late report of the Geneva Experiment Station.

FIG. 15.

Since the spores can only develop in a moist atmosphere, it is quite evident that, if we could keep our cherries perfectly dry, there would be no rot. But, as this is impossible, we must endeavor to find some other means of preventing the evil. The spores have great vitality and preserve their generative powers from one season to another. The old ripe cherries which dry up and hang upon the trees during the winter, as well as the fallen cherries beneath the trees, are the means of carrying the fungus through to the following season. Any mode by which these could be destroyed would be helpful, whether by burning or by allowing the pigs to run in the orchard, so as to eat up all that drop. Probably the most reliable method of combatting the evil will be found in the universal remedy of spraying the trees with the Bordeaux mixture as soon as possible after the blossoms have fallen.

PLUM LEAF OR SHOT HOLE FUNGUS (Septoria Cerasina).— The leaves of cherry and plum trees are often affected by this fungus, the appearance of which is well represented in fig. 16.

The holes are frequently so round and even that they awaken considerable curiosity on the part of the observer as to their cause, but lately the mystery has been explained by Prof. Scribner, who says that they are caused by a fungus which is very widely distributed throughout the States east of the Mississippi. Though not a very serious pest, it often inflicts considerable injury both upon the cherry and the plum trees, by interfering with the proper function

The

of the leaves, causing them to drop prematurely, sometimes as early as the first of August. leaves attacked show at first, scattered here and there over the surface, dark purple spots, visible on both sides, varying from one twentyfourth to one eighth of an inch in diameter. After a brief period, the tissue covered by these spots becomes dead and brownish in color. On examining one of these brown spots under the microscope there will be detected from one to several minute black points. These are the fruits of the fungus, like little capsules, in which the spores of the fungus are produced in great abundance. These are very slender and many times longer than broad, and quite transparent. They are usually divided by one or more cross walls into two or more cells, and each cell in every spore is capable of producing a new growth of this parasitic

plant.

FIG. 16.

Fig. 17 represents a highly magnified section through the leaf, including one of the four capsules, and at a, above, are shown some of the spores, still more highly magnified. The parasite buries itself within the leaf tissue and, therefore, any treatment, to be successful, must be preventative. Spraying the trees with the copper carbonate compounds, or with the Bordeaux mixture, for preventing the plum or cherry rot will result, in all probability, in preventing the growth of this fungus.

STRAWBERRY LEAF BLIGHT (Sphærella Fragaria).—This is another of the well known difficulties which meet the grower of small fruits in Ontario. It is commonly spoken of as the "strawberry rust,' ""sun scald," or "spot disease," although, according to Prof.