154 MASS. EXPERIMENT STATION BULLETIN 154. 



the stems of the alfalfa and bearing inconspicuous flowers of 

 the same color. This parasite tends to spread rapidly; it 

 renders the crop unpalatable. If noticed in the field it is best 

 to cut the crop and burn it, plow the field and not put it into 

 alfalfa again for a considerable number of years. Alfalfa 

 dodder is not yet general in this State, and most energetic 

 measures should be taken to exterminate it where it appears. 

 If it shows in a field it is safe to conclude the seed of the 

 dodder was mixed with the alfalfa seed. It is so fine it usually 

 escapes detection by the average buyer. Dealers should be 

 asked to guarantee alfalfa seed free from dodder. In cases 

 of doubt samples of seed should be sent to the experiment 

 station for examination. 



Weeds. — Annual weeds will give but little trouble, provided 

 such methods of seeding as are later recommended are fol- 

 lowed. Especially is this true if the thorough preparatory 

 tillage recommended w^hen the seed is to be sown in late summer 

 is followed. In the case of spring seeding, either with or with- 

 out a nurse crop, annual weeds may compete with the alfalfa 

 for water and food. If the growth is thick and rank the weeds 

 may be clipped with a mowing machine set about 3 inches 

 high. It is a mistake to sow alfalfa in fields heavily infested 

 with the roots or seeds of perennial weeds. Especially is this 

 true of witch grass, the competition of which alfalfa is wholly 

 unable to withstand. 



Grasses and Clovers. — In our better soils, and with our 

 humid climate, some of the grasses and clovers, particularly 

 Kentucky blue grass and white clover, tend to come in and 

 gradually to crowd out the alfalfa. The tendency in this 

 direction is increased by the use of barnyard or stable manures 

 which, besides supplying large amounts of nitrogen (highly 

 favorable to the growth of grasses), often carry their seeds as 

 well as those of clover. It cannot be regarded as good practice 

 to top-dress a well established field of alfalfa with manure 

 of any kind. So doing, besides being objectionable from the 

 points of view already stated, must be regarded as wasteful 

 of nitrogen, the most costly plant-food element, since the 

 alfalfa if well established is able to take this element so largely 

 from the air. 



