274 STATE HORTICULTURAL SOCIETY. 



GENERAL CHARACTERS. 



We adopt the name " Leaf -blight" for the malady in question, as it is a 

 name not only frequently heard, but is appropriate considering the origin 

 and the effects of the disease. Of the various other names found in various 

 publications, the most descriptive is the "spot-disease," given on account 

 of the appearance of the blighted areas on the leaf. The names "sun-burn," 

 "sun-scald," "strawberry rust," are also frequently applied, and the enumer- 

 ation of the above will recall to the mind of any strawberry grower this 

 troublesome disease. 



In all sections, it is generally conceded that this blight appears on the 

 new leaves about the time the fruit sets, and if it goes on unchecked is at 

 its worst during the hot weather prevailing just after the crop is gathered. 

 If continuous cloudy and rainy weather in May and June, causing a rank 

 growth of leaves, is succeeded by hot, dry weather in July and August, the 

 strawberry suffers a great check ; and if it has also been exhausted by a 

 large crop, it is, in this state of weakened vitality, usually attacked with 

 great severity by the fungus, Sphaerella Fra(i<(ria\ 



The latter, like many of the flowering plants, has various stages of devel- 

 opment, each of which taken by itself exhibits characteristics very different 

 from any of the others. The observations and experiments made last 

 winter and spring showed the following stages of growth and reproduction, 

 all proven to be connected: first, the vegetative stage, or that of the 

 mycelium ; second, the early conidial stage ; third, the scleroiium stage, 

 — a winter conidial stage ; fourth, the perifhecium stage. The spores or 

 reproductive bodies of the second and third are extremely abundant, but 

 shortlived ; those of the fourth stage, being "resting" spores, are few but 

 of comparatively long duration. 



There are several other spore-like growths on the strawberry which some 

 writers believe to be yet other forms of SphaereUa Fragario', but which 

 'our experiments thus far have either not dealt with or else given no 

 proof of such connection. These are the "stylospores" and the "spermatia" 

 of Tidasne. Besides the above there are ten or more species of fungi, all pre- 

 sumably distinct from Sphaerella, found parasitic on the strawberry, none 

 of which, excepting Ascochyfa Fragaricp, Sacc, are known to produce any 

 serious disease of the host. 



When a "spot" first appears on a young leaf in June it is brownish, or 

 more usually red or red-purple, and rapidly assumes the character it has at 

 maturity. When fidly developed it has a center nearly circular, dead-white, 

 and usually from 3 to 6 millimeters (^ to | of an inch ) in diameter. This white 

 center is surrounded by a distinctly red or purple border 1 to 3 millimeters 

 wide, which shades into dark purple-brown next to the white center. These 

 spots often join, when the leaf is badly diseased, so as to form a single 

 large discolored area. 



THE MYCELIUM OR VEGETATIVE PORTION. 



The discolorations above mentioned are caused by the mycelial stage of 

 the fungus, which, with the summer conidia immediately connected with it, 



June, 1889, the observations, artificial cultures and infections. While the writer watched the course of 

 the work, and made some of the later experiments, most of the new matter here given is drawn from 

 Miss Snow's observations and records ; and the figures after Fig. 2 are from original ones made by her. 

 A long series of exijeriments on the possible development of sexual organs and pycnidia, and on the 

 growth of the perithecium, are omitted here, as they are not yet complete, and it is Miss Snow's intention 

 to continue this investigation. 



