278 STATE HORTICULTURAL SOCIETY. 



not ordinarily directly infect the host-plant, but accomplished this only 

 through the conidia it produced. Ascospores were then sown upon the 

 leaves of rapidly-growing plants, and in four days the mycelium was 

 observed ramifying over the epidermis, but in no case could it be found 

 penetrating it. Furthermore none of the plants on which ascospores were 

 sown became spotted, with a single exception, and. this was proven to 

 have been diseased before the ascospores were placed upon it. The evid- 

 ence, therefore, is in favor of the above hypothesis; and as numerous conidia 

 are produced from the mycelium growing from one ascospore, the fungus 

 is enabled to increase many fold the effectiveness of its attack. 



Several authors have indicated by figures and descriptions the develop- 

 ment of mycelia and basidia from the surface-cells of the perithecium, 

 particularly about the ostiolum. These were said to bear conidia, indistin- 

 guishable from the summer or the sclerotium conidia. Although especially 

 sought for, no such out-growths were observed arising from the walls of 

 the perithecium. The fact that the ascospores naturally germinate within 

 the perithecium, and the mycelial filaments grow not only out of the 

 ostolium, but burst the walls of the perithecium, and grow through its 

 rents, led to the conclusion that observers may have been, in some cases, 

 deceived by the out-growth, supposing it to be directly from the wall-cells 

 of the perithecium itself. 



CONDITIONS AFFECTING THE DEVELOPMENT OF THE BLIGHT. 



It has been intimated in the early part of this discussion, that a wet May 

 or June succeeded by a hot, perhaps dry, summer causes the parasite to 

 develop rapidly ; that the production of a large crop of berries has frequent- 

 ly been followed by heavy, perhaps fatal attacks of the blight.* It might 

 be added that wet, undrained soil greatly favors it. All these favoring 

 conditions may be reduced to or result in a single one, namely, an unhealthy 

 or weakened plant. On the other hand a season either prevailingly dry or 

 with abundant moisture throughout, is quite unfavorable to the devel- 

 opment of the disease. There was an enormous amount of the fungus in 

 many fields in 1888, and therefore an abundant supply of mycelium and 

 spores, both of which in the spring of 1889 developed vigorously on the old 

 leaves. But the leaves of this season's growth have been conspciuously 

 free from the spots. This is true not only of plants reasonably healthy 

 last year, but of beds where the leaves of last year still bear witness of the 

 great ravages at that time. The Wilson, very susceptible to the disease, and 

 the Sharpless, supposed to resist it more or less successfully, are both quite 

 free from it in this vicinity. The season has had an abundant rainfall, no 

 drought, and a comparatively even temperature, all of which have favored 

 the normal growth of the foliage. As a consequence the fungus has 

 failed to obtain as strong a foot-hold as usual. 



Anything promoting health in the strawberry plant and normal con- 

 ditions about it is pretty sure to fortify it against its enemy. Its likes and 

 dislikes in regard to soil, mulching, drainage, and cultivation ought to be 

 studied as carefully as a grower of choice flowers studies these things. 

 To forestall the unfavorable influences of weather, fungicides must be 

 resorted to. 



* J._ M. Smith, Second Ann. Report Wise. Agr. Exper. Sta., p. 56, says: "Four fifths of the plants (in a 

 certain field) were dead from rust; and that, just as far as they had borne heavily but no further." 



