242 



are the principal means by which the fungus is carried through the 

 winter and the presence of an ascigerous form, described by Sorauer, 

 seems almost unnecessary to a niaiiiteiiance of the disease in a region 

 once infested. 



The practice of allowing stocks to remain in the nursery rows when 

 leaf-blight has affected them so severely as to render them unburi- 

 able, seems unwise when considered from a hygienic standpoint. 

 Such stocks are almost sure to harbor the parasite in its winter form 

 upon their slender branches, which are lacking in vigor. It is from 

 these stocks that the disease apparently spreads to other plantings of 

 seedlings in the vicinity and to such budded stocks as are susceptible, 

 it would seem advisable, therefore, that when leaf-blight causes a large 

 number of failures in the seed bed, the diseased seedlings should be 

 headed back to within 1 or 2 inches of the ground and all side shoots 

 likely to harbor the parasite removed. Such procedure would un- 

 doubtedly decrease the liability to so early an attack of the disease 

 and enable growth to be made before the malady had time to spread 

 from infected localities. The same immunity as that shown by rap- 

 idly growing "buds" may prove here a valuable factor. It has been 

 objected, however, that the simultaneous appearance of several shoots 

 from the headed back seedling would prevent, or at least materially 

 hinder the budders in their work the following fall. This obstacle 

 could be overcome by the early removal of all but one shoot. It seems 

 to me that this method of eradicating the disease is sufficiently prom- 

 ising to warrant a thorough test. The matter of protecting seedlings 

 by wind-breaks has not been thoroughly tested to my knowledge, and 

 from observation on the spread of the disease I am inclined to believe 

 it is worthy a systematic trial. The freedom from leaf blight, which 

 isolated blocks of pear seedlings often show, tends to confirm the ob- 

 servation that the malady travels quite slowly from seedling to seed- 

 ling. In an experimental block of seedlings mentioned below it 

 required nearly two months for the disease to travel from the east to 

 the west end, a distance of 150 feet. 



, Two quite distinct experiments were made with a view of preventing 

 this disease, one inaugurated in 1891 to test the effect of fungicides 

 upon stocks, and the other carried on during the season of 1892 with 

 seedlings in the seed bed. The results of only the former experiments 

 are recorded here and an account of the latter is reserved for future 

 publication. 



EXPERIMENTS WITH STOCKS. 



These 'experiments were inaugurated in the spring of 1891 and con- 

 tinued until the fall of 1892. The stocks planted in 1891 were sprayed 

 both seasons, the design being to ascertain the effects of two consecu- 

 tive years. The results are here presented briefly and the minor details 

 are to be found at the close of the article. 



