241 







details, of interest only to those who are pursuing similar studies, are 

 given in. small type at the close of the article. 



PEAR LEAF-BLIGHT (Entomosporium maculatum Lev.). 



This disease is perhaps the greatest obstacle to the profitable pro 

 duction of pear stocks. The principal injury is caused by a premature 

 defoliation of the seedlings. When such defoliation takes place early 

 in the season, as is quite commonly the case, the young seedlings are 

 forced to form a new set of leaves, presumably at great expense to the 

 reserve material stored for use the coming spring. Often this forma- 

 tion of new leaves is repeated two or three times, the seedling finally 

 becoming too exhausted to continue the struggle. If the following 

 winter be survived, enough growth may be made to render budding 

 possible. 



Although the disease is very abundant on bearing trees further south, 

 it seems to be confined in western New York, at least in its severe 

 attacks, to one, two, and three year old seedlings, occasionally defoli- 

 ating a budded stock of some susceptible variety like the Flemish 

 Beauty. All ordinary budded stocks are commonly immune from the 

 disease, although the stocks into which the buds are inserted may 

 have been diseased before being budded.* So far as the author's observa- 

 tions go the fungus causing the disease does not attack the seeds of 

 the pear or the cotyledons of the young seedlings until two weeks after 

 the appearance of the latter above the surface of the soil. Early in the 

 season it attacks only the foliage, but later, as the defoliation continues, 

 it is found on the succulent growing tip of the stem. For 3 or 4 inches 

 from the terminal bud the bark is covered with small, sunken spots, 

 bearing in their centers the mature fruiting bodies of the fungus, this 

 condition first becoming noticeable about the middle of August. As 

 first pointed out by Sorauer,f it is in these sunken spots that the 

 parasite passes the winter. In America the parasite lives from 

 year to year, as it does in Germany, upon the bark of the grow- 

 ing seedling and infects the young leaves upon their first appearance 

 in the spring. On May 20, before the foliage of last season's un- 

 budded stocks was two-thirds grown, mature pustules were found 

 upon the young leaves in immediate proximity to these spots upon the 

 twigs. A microscopic examination of the spots revealed the parasite 

 in an active condition. There is little doubt that the infected twigs 



* The terms "seedlings" and "stocks" are here employed as in common use among 

 nurserymen. A seedling hi nursery parlance means a plant grown from seed before 

 it is transplanted into the nursery row, while the term stock is used to designate the 

 seedling after transplanting either before or after budding. Whenever I have referred 

 to stocks which have been budded 1 have used the terms "budded stocks" or "buds." 



\Soraner, P. Haudb. d. Pflanzenkraiikheiten. Zweitc Aufl., 1886, vol. n, p. 373. 

 Momitschr. d. Ver. ztir Boturd.d. Gartenb. Kgl. preuss. St., Jan. 1878. (Cited by 

 Frank, Krankh. d. Ffl., 1880, p. 590.; 



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