CHAPTER III. 



HISTORY OF THE TREATMENT OF PEACH LEAF CURL. 

 THE EUROPEAN SITUATION. 



That the present outline of the gradual development of methods for 

 the treatment of peach leaf curl in the United States ma}^ be properly 

 appreciated, it is desirable to first show the conditions prevailing in 

 Europe as presented bv some of the leading European writers on plant 

 diseases. Prillieux, in an interesting paper on peach leaf curl, pre- 

 pared in 18T2, describes the fungus Edcoascm deformaTis and its action 

 on the tissues of its host.' He states that the fruiting fungus should 

 be looked upon as the center of infection, and that it is desirable to 

 remove the diseased leaves as thoroughly as possible and to destroy 

 them. He also states that this work should be supplemented by the 

 cutting off and burning of diseased branches. In 1878 Winter- stated 

 that the only way to prevent this disease is to destroy the fungus by 

 carefully removing the affected leaves, and by protecting the trees from 

 rain during the unfolding of the leaves, as rain favors the spread of the 

 parasite. The same year Felix von Thiimen wrote of Exoascus pruni^ 

 the fungus causing plum pockets and closely related to Exomcua defor- 

 mans of the peach, ^ but made no recommendations for its treatment. In 

 1885, however, he again spoke of the plum pocket disease and pointed 

 out that it can not be removed except by severe cutting back of the 

 new and old wood of the affected trees.* In 1880-81 Frank, in the 

 second volume of the first edition of his work on plant diseases, rec- 

 ommends the cutting back of the twigs as a cure for leaf curl, and the 

 quick removal of the diseased leaves for prevention." 



In 1886 the well-known work of Sorauer on plant diseases^ appeared. 

 The treatment recommended by this author is somewhat similar to 

 that recommended by Frank. He says, in speaking in a general way 



1 Prillieux, Ed., Bull, de la Soc. Bot. de France, 1872, T. XIX, pp. 227-230. 



2 Winter, Dr. Georg, Krankheiten der Kulturgewachse, Leipzig, 1878, p. 47. 

 ^Thiimen, Felix von. Die Pilze und Pocken auf Wein und Obst, Berlin, 1878, III, 



Fungi Pomicoli, pp. 88, 89. 

 *Thunien, Felix von, Die bekampfung der Pilzkrankheiten unserer Kulturgewachse, 



Vienna, 1886, p. 71. 

 * Frank, Dr. A. B., Die Krankheiten der Pflanzen, Breslau, 1880-81, Theil II, 



p. .526. 

 fi Sorauer, Dr. Paul, Handbuch der Pflanzenkrankheiten, second edition, Theil II, 



p. 281. 



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