No. 4.] ALFALFA IN MASSACHUSETTS. 133 



Soil Inoculation. 

 In localities in wliich sweet clover does not naturally grow, inocula- 

 tion of the seed or soil with the bacteria which develop nodules upon 

 the roots, and which give the plant the capacity to assimilate at- 

 mospheric nitrogen, is advised. If sweet clover is indigenous in the 

 locality such inoculation is unnecessary, as the bacteria which develop 

 nodules on the roots of sweet clover appear to be identical with those 

 found on alfalfa roots. If inoculation is necessary it can be carried 

 out in two ways : — 



1. An artificial culture may be obtained and used in accordance 

 with the directions accompan3'ing it. »Such cultures are sent out both 

 by the United States Department of Agriculture, Washington, D. C, 

 and by a number of private companies. The cultures now offered 

 appear to be much superior to those earlier produced, and the most 

 recent experiments at the experiment station with a culture fur- 

 nished by one of the private companies have given very satisfactory 

 results. The use of a culture will, on the whole, be found rather less 

 troublesome than the second method. In ordering a culture, it is 

 necessary to name the crop for which it is wanted and the area which 

 is to be sown. 



2. Soil from an old and successful alfalfa field may be mixed with 

 the soil of the area to be sown ; 300 or 400 pounds per acre, if thoroughly 

 stocked with the needed bacteria, will prove sufficient, and it is possible 

 that less would answer. If soil is used, it should be remembered that 

 exposure of the gei'ms to the light, even if only for a short time, de- 

 stroys their vitality. It is advisable, therefore, to harrow in the 

 germ-carrying soil as promptly as possible after spreading. 



Leaf Spot or Rust. 



Alfalfa appears to be peculiarly subject in our climate to this 

 parasitic disease. The presence of the disease is indicated by the 

 appearance of small, dark-colored spots upon the lower leaves. If 

 the weather conditions are favorable to the rapid increase of the 

 parasite it spreads quickly to the upper leaves, and later first the 

 lower leaves and then the upper may turn yellow and fall. In some 

 cases the disease shows itself only on the lower leaves; the foliage on 

 the upper part of the plant continues healthy and the injury may not 

 be great. In damp or rainy weather the disease, however, often 

 spreads with great rapidity, the growth of the crop is checked and the 

 vitality of the plants is greatly weakened. 



When this disease shows a tendency to spread rapidly, it is best to 

 cut the alfalfa immediately. Under this treatment a healthy growth 

 will soon start, while if the diseased plants are allowed to stand they 

 will be greatly weakened, and the subsequent crops much reduced. 

 During the past season leaf spot has been unusually prevalent and in 



