MYCOLOGICAL SECTION. 109 



The time when the sulphur should he employed is in early summer, 

 at the first appearance of the Mildew, and the application is most 

 effective when made on a warm, bright day, after all dew has evapo- 

 rated. However well this application may be made, it is almost cer- 

 tain that some of the fungus threads and many of the conidia will 

 escape destruction. From these, or from spores brought from other 

 vineyards, a new infection may appear in from twenty to thirty days, 

 when a second sulphuring should be made. 



In districts particularly subject to this disease it is recommended 

 that the vines be sulphured— first, when the young shoots are about 4 

 inches long; second, at the time of blossoming; third, some days be- 

 fore the turning of the berries. In bad seasons the mildew may make 

 its appearance between these periods, when of course additional sul- 

 phurings should be made. Particular emphasis is placed upon the 

 sulphuring at the time of bloom, for the flowers are almost certain to 

 be rendered sterile if attacked by the Uncinula, and every precaution 

 should be taken to prevent, if possible, the development of the Mil- 

 dew at this time. 



III. — Black-Rot. 



Fhysalospora Bidwellii, Sacc. 



(Plate III.) 



The Black-Rot of the grape is a disease familiar to all grape-growers 

 of the Middle Atlantic and Central States. It is known to prevail 

 with greater or less severity — in some instances causing the total de- 

 struction of the grape crop — in Alabama, Georgia, Illinois, Indiana, 

 Maryland, Michigan, Mississippi, Missouri, North Carolina, South 

 Carolina, New Jersey, Ohio, Pennsylvania, Tennessee, Virginia, and 

 Kansas. 



It is now more than twenty-five years since Dr. George Engelmann, 

 in a paper communicated to the Saint Louis Academy of Sciences, 

 clearly pointed out the characters of this rot and described the active 

 stage of the fungus which produces it. A great deal has been writ- 

 ten and published concerning this disease in more recent years, but 

 very little additional information has been acquired. The atmospheric 

 conditions favoring its development had already been pointed out, 

 and the fact that certain varieties were more subject to it than others 

 had already been noted, while to-day we are yet looking for an effi- 

 cacious remedy. 



The first manifestation of Black-Rot is the appearance of a livid 

 brown spot on some part of the berry; this spot gradually increases 

 in size until the entire grape is uniformly discolored, so that it appears 

 to be rotten, although its original contour and firmness are retained. 

 It usually happens that before the completion of this change the part 

 first affected becomes darker in color, and minute black pimples are 

 developed over the surface. At the same point the berry now begins 

 to lose its fullness, an irregular depression appears, which soon extends 

 into a general withering of the berry, the pimples meanwhile having 

 multiplied so rapidly as to cover its entire surface. The destruction 

 of the berry is now complete; it is hard, dry, shriveled to one-half or 

 one-fourth its original size, the folds of the skin being closely pressed 

 upon the seeds and raised into strong, prominent, and irregular ridges. 

 These last and the little pimples, which are easily seen with the naked 



