TWENTIETH ANNUAL MEETING. 17 



surface which characterizes the disease in its active stage; but we have not observed 

 the affected portion of the berry to become black or shriveled until the vegetative 

 career of the mycelium is apparently checked. Then the spermagonia make their 

 appearance on the surface, always at or near the point where the disease began, and 

 then the part immediately around and under them begins to grow black and shriveled. 



These two forms of fructification, in all probability, serve for the immediate 

 distribution of the fungus during the summer season. And from the fact that the 

 conidial, or third form, is only observed late in the season upon old diseased berries, 

 and the fourth form in the spring, it is probable that they are the means by which 

 the species is preserved from one season to another; in other words, that they fur- 

 nish the winter or resting spores. 



The conidia are little hair-like projections, which under favorable conditions grow 

 up from the surface of pycnidia, from which the contents are being extruded. They 

 are erect, and bear ui^on their distal end a few scattering spores. 



The fourth or supposed mature form is produced in the spring — about the month 

 of May, it is said — by the action of warmth and moisture u^jon old diseased berries. 

 A fruiting body is formed similar in every way to the first two, except that it con- 

 tains little elipsoid bodies called asci, which are fastened by one end to the bottom 

 of the capsule. These in turn contain a certain number of spores or germinating 

 bodies. This form is called the sporklium. 



The conditions necessary, then, for the advent of the black rot, are a lowered vi- 

 tality from imperfect nutrition, whether caused by exhaustion of the soil, by over- 

 bearing, or both; and the presence of the germinating bodies in some form of the 

 23h.ysalosporo Bidivellii. 



These conditions being present, how are they to be dealt with by the viticultur- 

 ist? 



Build up the strength of your vines with plant foods; fertilize, in other words, 

 and replenish the elements that have been exhausted from the soil by the constant 

 growth and bearing of the vines. 



Husband the strength of the vines also by cutting back; by trimming off the 

 old wood; and by preventing heavy crops. 



Destroy every vestige of the diseased fruit which may have remained over from 

 the previous season; destroy it by tire. And as a therapeutic measure, when the 

 grapes have attained a size at which they are from the surrounding conditions lia- 

 ble to an attack, or when the attack has been precipitated, use sulphurous acid gas 

 as a germicide. 



Use it in the following manner: Take a stick of roll sulphur and place it end to 

 end with a wooden stick of convenient length. Roll them both in a piece of thick 

 coarse cloth, such as a gunny sack, and light the sulphur. The cloth will cause it to 

 burn slowly like a torch. 



Take the torch in one hand and a watering-pot in the other. Sprinkle the fruit 

 slightly, and then fumigate. The water absorbs more or less of the gas, and holds 

 it in situ for a greater length of time than it would otherwise remain. 



Sulphurous acid gas is one of the most powerful germicides known; sulphur is 

 cheap, and the method effective. The operator can walk along his trellises and in a 

 very short time fumigate to a sufficient extent a large vineyard. 



So far as is known, Dr. Langworthy, of Leavenworth, is the originator of this 

 method, and to him is due the credit of an important advance in the treatment of 

 this disease, as well as the thanks of viticulturists. 



