232 EXPERIMENT STATION RECORD. 



Sometimes it it PI )(';i IS in Juno, to leappear again later in the sauie 

 year, or it may apjx'ar only once, in August or September. In 1892 and 

 181);> the disease had spread still farther throughout Italy. 



At the appearance of the disease the tip of the main stalk of the 

 clusters and its branches took on a brownish color. It spread more or 

 less rapidly, destroying llowers and the forming grapes, until the whole 

 cluster may become dried up, or sometimes only half of a single grape 

 may be affected, the rest remaining sound. Sometimes a few branches 

 of the cluster may be affected, the others showing no traces of the dis- 

 ease. If the disease appears later in the season its course is less rap- 

 idly run, but it is none the less disastrous. The dried grapes fall to 

 the ground oi', if they remain on the vine, become centers for spreading 

 the disease. 



Various authors have attempted to identify this disease as a phase 

 of a Avell-known bacillus, but the present author considers it totally 

 different from any hitherto described as affecting the grape. 



Observations ami experimental inoculations with i)ure cultures of the 

 bacteria seem to. show that varieties derived from Vitis vini/era, and 

 especially the white-fruited ones, are the most subject to this disease. 

 The bacteria develop only within certain limits of temperature. The 

 spores begin to grow when the night temperature doe.5 not fall l)elow 

 10 to 12° C, and ordinarily a, temperature of 32 to 35° checks the 

 development. The greatest and most rapid growth is made between 

 25 to 30'^ ('., provided there be sufficient moisture in the air. 



Vines wliich are exposed on the north and Avest are most liable to 

 attacks of the disease, as they are less subject to the drought. The 

 nature of the soil has no innnediate effect on the disease, biit it is indi- 

 rectly affected by the degree of hygroscopicity of the soil and its 

 ability to absorb and retain heat. 



The author made an elaborate botanical study of the bacteria caus- 

 ing this disease, and his methods of manipulation are given in detail. 

 The bacteria are easily found, as they penetrate all the tissues of the 

 fruit, the inllorescence, and parts of the flowers, especially in the 

 mesophyll tissue, and are even to be found in spiral vessels, cand)ium 

 layer, aiul fd)rovascular vessels. The bacilli of the disease when in 

 their natural condition, that is, when in the fruit, are thin, straight, or 

 slightly curved, with rounded extremities, 3 to 4 a^ long by 1 to 1^ /^ in 

 diameter. They move rapidly and are easily stained with aniline stains. 

 In the fruit they are never found in chains but always isolated, and in 

 some eases spore bearing. 



Numenms successful cultures and inoculations were made, the 

 methods and results of which are given in detail. The article is illus- 

 trated by 2 handsomely colored plates, showing some of the various 

 stages of the disease and the double-stained bacillus in position and 

 cultures. 



Recent contributions to mycology, I,. ]I, Pammel {Jt/L Sci., S US94), No. 4 

 pj). 1S3-191). ' \ • ' • > 



