430 MISSOURI STATE HORTICULTURAL SOCIETY. 



recovered, except some 20 or 30 quite dead, and bearing this year one 

 of the largest crops, without ever cutting off a blighted twig or limb at 

 any time, I read with complacency the dictum, "promptly remove- 

 every trace of the disease, and burn the branches," and enjoy the en- 

 thusiasm of the theorists. C. M. Hovey. 



APPLE SCAB AND LEAF BLIGHT. 



The following interesting abstract of an article by Prof. Wm. 

 Trelease in the 1884 report of the Wisconsin Experiment Station, was 

 prepared by Mr. Louis H, Pammel, a former special student of Prof^ 

 Trelease. 



In the first annual report of the Wisconsin Agricultural Experi- 

 ment Station, Prof. Wm. Trelease contributes a valuable paper on the- 

 Apple Scab and Leaf Blight, which deserves attentiun from every 

 thorough- going fruit grower. The apple leaf blight or mildew, so- 

 troublesome in recent years, is caused by a parasitic fungus, known 

 botanically as Fusicladium deudrilicum. The fungus causes the 

 leaves to have rounded, velvety spots, which are of an olive greea 

 color when young, but become darker with age, and in some cases, 

 almost black. The spots vary considerably in size, and may easily be 

 detected, most frequently on the upper side of the leaf ; at times they 

 are found to attack young twigs. These spots are the fruiting portion, 

 of the fungus, which has a concealed growing portion, which is a cor- 

 ruscation of one of these spots. The fungus in some way effects an. 

 entrance into the outer wall, or epidermis of the fruit, where it de- 

 velops a mycelium of closely interwoven, colorless threads. This com- 

 pact mass of cells, called the stroma, as it increases in thickness, soon 

 bursts the detached cuticle and produces, in contact with the air, a 

 comparatively small number of short, heavy, brown, and sometimes- 

 branched threads, which finally bear brownish, mostly one-celled 

 spores, but occasionally, in some of these spores there is found a cross 

 partition, a little above the middle, thus making it two-celled. These- 

 spores germinate by sending out a slender tube, which penetrates the 

 cuticle of the leaf and there develops in a new mycelium. In the 

 apple scab, the surface of the apple is disfigured by brownish or nearly^ 

 black spots, which appear at first as little pustules, surrounded by a 

 ragged white border. Older scabs have an irregular and somewhat 

 flaky surface, and are generally checked by pale brownish cracks.. 

 Some apples are so badly covered with this crust that very little healthy 

 skin remains. A section shows that it consists of a fungus which lives 

 in the cavities of the thick walled epidermal cells, where its mycelium^ 

 grows at the expense of these and the cells immediately beneath. 



