266 COMMON WEEDS 



he observed " the bad effects of sowing impure samples 

 (of clover seed) purchased without guarantee." On the 

 other hand, in the Swiss Leaflet already quoted, it is stated 

 that, " Because foreign red clover is often badly infested 

 with Broom-rape, one now and then hears the opinion 

 expressed that the latter is introduced with foreign 

 clover seed. This is not so. In the many thousand 

 clover seed samples which have already been examined, 

 the seeds of Broom-rape have never been found. This 

 is easily understood. Broom-rape ripens its seeds 

 much earlier than red clover. By the time the clover 

 is harvested for seed the last of the parasite has dis- 

 tributed all its seed. And even if it did get into the 

 clover seed, it would, on account of its small size, be 

 completely removed by the clover-cleaning machine. 

 Where Broom-rape appears, its seeds were certainly already 

 present in the soil / " 



2. When a clover crop is found to be infested the 

 Broom-rape may easily be pulled up by hand and 

 burnt. If it be known that clover is infested, the crop 

 should be cut early in order to prevent the Broom-rape 

 seeding, and the clover should then be encouraged to 

 grow thickly and strongly, so that it may smother the 

 weed. Ground lime and potash manures may be use- 

 ful in this way if judiciously applied ; and simply 

 manuring with nitrogen, which in any other case is not 

 advisable for clover, has been followed with good 

 results as a preventive. 1 The better the land is pre- 

 pared and manured before sowing the less will the crop 

 be damaged by the pest. Sorauer remarks that in a 

 case of widespread infestation the chief means of com- 

 bating this pest consists in the prevention of seeding, 

 because spreading by scions or shoots is slow, and 

 easily preventable by uprooting the plants. The pre- 



1 Swiss Leaflet cited. 



