DRUPACEOUS FRUITS 135 



causes twigs to die. The disease may be readily recog- 

 nized by the dead bark thickly studded with small pyc- 

 nidia. Burning of the diseased branches will prevent the 

 spread of the pest. 



Yellows. — The peach yellows has been known in the 

 United States something like a hundred years. From a 

 region near Philadelphia, as a center, it has spread until 

 now it is known throughout a large territory and is con- 

 stantly extending its frontier in every direction. The 

 disease is of unknown cause, but it has been proved beyond 

 question that it is contagious. The roots of diseased 

 plants, however, do not infect the soil, and trees may safely 

 be set in the places from which diseased trees have been 

 removed. 



Recognition marks, which leave no uncertainty as to its 

 identity, are described by Smith ^ as follows: " Prematurely 

 ripe, red-spotted fruits, and premature unfolding of the 

 leaf buds into slender, pale shoots, or into branched, broom- 

 like growths, are the most characteristic symptoms of yel- 

 lows. The time of ripening of premature fruit varies 

 within wide limits ; sometimes it precedes the normal 

 ripening by only a few days, and at other times by several 

 weeks. The red spots occur in the flesh as well as on the 

 skin, making the peach more highly colored than is natural. 

 The taste of the fruit is generally inferior and, often insipid, 

 mawkish, or bitter. Often this premature ripening is the 

 first symptom of yellows. The peaches are then of good 

 size and quite showy, and occur on trees in full vigor, upon 

 hmbs bearing abundant green foliage, and sometimes also 

 other fruits which afterwards ripen normally. 



1 Smith, E. F., U.S. Dept. Agr. Farmers' Bui. 17, p. 7, 1894. 



