400 FORAGE PLANTS AND THEIR CULTURE 



land becomes sick to naturalized wild plants of red and 

 white clover. Several experiments have shown that 

 clover plants grown from cultivated seeds disappear 

 largely in 1 year, while those from wild plants persist 3 

 to 5 years or more. One experiment with red clover 

 resulted in the plants from cultivated seeds lasting but 

 2 years, while those grown from seed gathered in an old 

 meadow lived 5 or 6 years. 



472. Reduction of acreage probably due mainly to clover 

 sickness. The statistics of the thirteenth census of the 

 United States, 1909, shows that a great decrease in the acre- 

 age of clovers has taken place since 1899, especially in the 

 eastern part of the country. Every state east of the 95th 

 degree of longitude, excepting Illinois, shows such a decrease. 



The average decrease in the acreage of " clover " for 

 the whole United States was 40 per cent. In certain 

 states the decrease was much greater, being 88 per cent 

 in New Jersey, 78 per cent in Pennsylvania and 65 per 

 cent in Indiana. In the states immediately west of the 

 Mississippi River the decrease was not so great, but is 30 

 per cent in Missouri, 23 per cent in Minnesota and 16 per 

 cent in Iowa. In the states farther west the figures are of 

 less interest, owing to the large acreage of new land brought 

 under cultivation and the general preference for alfalfa. 



While the significance of the figures is not wholly clear, 

 the most probable explanation is that it is associated with 

 the increasing difficulty in securing stands of red clover. 

 The striking contrast in the figures for 1899 and 1909 

 may in part be due to unusual conditions in the latter 

 year but it does not appear from records that there 

 was undue loss from winter-killing or other climatic causes 

 in that year. The extent of the reduction in acreage is 

 shown in the following table : 



