464 EXPERIMENT STATION RECORD. 



zation of the mixture which is used in purifying illuminating gas. This mixture is 

 said to be composed of 30 kilos of iron sulphate, 15 liters of calcium hydrate, and 10 

 liters of wood sawdust. During the process of purification of the gas the sawdust 

 takes up a large amount of the iron of sulphate, and, l)eing a refuse in gas manufac- 

 ture, is very cheap, costing less than one-tifteenth of the price of iron sulphate. 

 Where this mixture is used it must be allowed to stand for some days, and stirred, 

 to allow the gas which had been absorbed to escape. , 



DISEASES OF PLANTS. 



Report on the fung-us diseases studied at the botanical laboratory of the 

 agricultural institute of Gembloux during- 1900, E. Makchai. (J!uI. A</r. [Brus- 

 sefe], 17 {1901), No. 1, pp. 4-iS, fig.^. 5). — A report is given of a numljer of fungus 

 diseases which were investigated during the season Among the prominent ones 

 were tomato rot, mildew of cauliflower, rust of currants and white pine, a mold on 

 the stems of potato, witches' brooms of cherries, damping off or rot of young pea 

 seedlings, a sclerotium disease of onions, a leaf spot of currants, scab of tomatoes, and 

 a bacteria] disease of beets. 



The tomato rot was caused by Phytophthorn mfestanfi, anfl ]irove<l very destructive, 

 the conditions during the ripening season having apparently been favorable for the 

 raj)id <levelopment and spread of the fungus. It was controlled, however, where 

 Bordeaux mixture had been thoroughly applied to the plants for some time j^receding 

 and during the ripening period. 



The mildew of cauliflower, which is caused by Peronoapora parasitica, has proven of 

 considerable loss to market gardening, and it is stated that the market gardeners 

 in the vicinity of Paris, upon the recommendation of Maxime Cornu, successfully 

 combated this disease bj' spreading about the plants wood sawdust saturated with 

 copper sulphate as a mulch. Where this was used, it is said there was no loss by 

 this disease. 



The relation ])etween the rust of gooseberries and that attacking the wliitc pine is 

 pointed out. The fungus, to which the name Cronarliuin rihicolnm is given, is 

 described in its different ])hases on the 2 host plants. The fungus is quite de.struc- 

 tive on pine seedlings, and its suppression is recommended by the ))urning of all 

 diseased parts of both pine and (currant. 



The mold of potatoes described is said to be an unusual one and due to the fungus 

 Hyporhnus solani. The lower part of the petioles and sometimes the lower leaves, and 

 occasionally even the stems, of the potato are covered with ashy splotches. While 

 giving the plants an unsightly ajjpearance, it has so far been of little a])preciable 

 injury. It is superficial in its attack, and if serious injury is threatened could be pre- 

 vented by the use of any of the better fungi(-ides. 



The disease of pea seedlings reported is due to Tfiielaria hasicola, and tiie fungus 

 was particularly abundant upon plants in water cultures which were Ijeing grown to 

 study the subject of root development. It spread quite rapidly, destroying one- 

 fourth of the plants in a very short time. It is thought to have been an unusual 

 occurrence that this fungus should have developed in the water cultures, as it is 

 ordinarily of terrestrial growth. 



The scab of tomatoes described is caused by a new species of fungus, to which the 

 name Dendrodorliiutn Iyco]>t;rsici is given. A technical descrii)tion of the fungus is 

 given, and its mnthod of attack upon the fruit is mentioned. It first appears upon 

 the immature fruit, causing large grayish blotches which spread ra})idly and running 

 together envelop more or less of the fruit. Underneath these spots the fruit will be 

 found to be in an advanced stage of decomposition. It is believed that the condi- 

 tions under which the tomatoes were grown were largely responsible for this disease, 

 it having developed in a shady situation. The author believes that growing tomatoes 



