DISEASES OF PLAISTS. 641 



of its introduction, and spread. The various characteristics of the 

 plaut as a weed are pointed out. It has been estimated that a plant of 

 medium size ripens about 8,250 seeds or fruits, and of this number about 

 10 per cent are capable of immediate germination, 00 per cent remain- 

 ing dormant until the following spring, or doubtless some are of longer 

 vitality. 



The i^riclily lettuce is a native of Europe and was introduced into 

 this country about 30 years ago, the first record of its observation being 

 at Cambridge, Massachusetts, in 1803. At the present time it has spread 

 nearly all over the United States, but it seems to find the most congenial 

 domain in the valley between the Alleghany and Eocky mountains 

 between 40 and 43° north latitude. Its introduction into Indiana seems 

 to have been subsequent to 1881, and it is now reported as a pernicious 

 weed in 29 of the 92 counties of the State. The author considers its 

 extermination impracticable, but it may be held in subjugation by 

 mowing and ujirooting so as to prevent seeding to as great a degree as 

 possible. 



The ])lant is somewhat interesting from the habit of its stem leaves 

 arranging themselves into vertical position with their edges directed to 

 the north and south. It is one of the two best known of the so-called 

 compass plants. 



The text of the Canadian thistle law is quoted and similar legislation 

 urged against this new pest. 



Concerning the temperature of germination experiments (Oesterr. Landiv. 

 WocheuM., 35 {1S94), p. 294; Bot. CvntbL, 61 (1S95), No. 2, pp. 52,53).— The author 

 reports the advantage of an intermitteut temperature for the germinatiou of g-rass 

 seeda. 



Number of germinative seeds in a pound or bushel of grass and clover seed, 

 W. Carhutheks (Jour. Hoy. J<ir. Soc. Eiifiland, Sdser., 5 {1S94), No. 20, pp. 797-799). 



Reports of Skara Chemical and Seed Control Station for 1892 and 1893, O. 

 Nylander {Skara (Sweden), Jleportfor 1S92, pp. 28; Report for 1893, pp. 25). 



The Russian thistle in Nebraska, C. E. Bessky {A<jl. Set., S (1S94), No. 6-9, p. 

 2S6).- — An account is given of the introduction aud spread of this weed in the State, 

 and a report of what precautionary measures have been adopted by the station to 

 prevent its spread. 



DISEASES OF PLANTS. 



Peach yello-ws, L. H. Bailey {New YorJc Cornell 8ta. Bui. 75, pp. 

 393-40S, fi(js. 7). — During the past season the author has made a careful 

 study of the peach industry of western New York, and in nearly every 

 region has found the yellows present, and particularly bad in Niagara 

 County, which is in the leading peach section of the State. He found 

 tliat truit growers were not always able to distinguish peach yellows 

 from the attack of borers or from growth in orchards which are not cul- 

 tivated OT i)runed, aud on this account he presents figures and descrip- 

 tions of the disease ia order that it may be more readily distinguished. 



