170 



WEEDS OF FARM LAND 



annual meadow-grass, knotgrass, black bindweed, spurry, and 

 large field speedwell were very occasionally found dominant, 

 but much less frequently than they were in other cases. 



4. (a) Weeds Specially Associated with Peas and Beans. 



In spite of the difference in soil conditions under which 

 peas and beans are grown they carry a very similar weed flora. 

 These crops are different in habit from any others grown on a 

 farm ; the individual plants are very strong growing, but in 

 the earlier stages they do not cover the ground to the same 

 extent as a young, healthy crop of seeds. Later on in life 

 peas and beans are as efficient smother crops as are seeds, but 

 the diversity of their earlier history influences the weed flora 

 considerably, so that the plants that are encouraged or injured 

 by the two classes of crops are entirely different. Peas and 

 beans are regarded as being the dirtiest crops on a farm, 

 because the weeds have a fair opportunity of establishing them- 

 selves while the crop is young ; little cultivation can be carried 

 out for fear of damaging the peas and beans, and many of the 

 weeds thus become strong enough to withstand the later 

 smothering action. Only two weeds, black bent and corn 

 buttercup, receive special encouragement from this type of 

 crop, and both these are correspondingly prevalent among 

 wheat, and are discussed under that heading also. 



TABLE XV. WEEDS SPECIALLY ASSOCIATED WITH PEAS AND BEANS. 



Black bent (Alopecurus agrestis) is profoundly influenced 

 by cultivation. If once it gets a fair start and is not interfered 

 with too much it can hold its own well, but if badly dis- 

 turbed in the early stages it has very little chance. For this 

 reason it is not usually a serious pest, ordinary rotation 

 farming keeping it in check. Peas and beans afford a most 

 congenial shelter for it, the comparative openness of situation 

 at the outset and the subsequent lack of cultivation providing 



