igS DISEASES OF THE SWEET PEA 



poses, the problem of handling sick soils 

 becomes a more difficult matter. In this 

 case neither the formaldehyde nor the 

 steam methods are applicable, since either 

 is too expensive when used on a large scale 

 and hence is not practical. There are, 

 however, other control measures which may 

 prove helpful. 



(a) Cleanliness, It is a common prac- 

 tice to allow sweet pea plants which have 

 passed their usefulness to winter over in 

 the field. As spring comes, the dead vines 

 are plowed under. In cases of fall plow- 

 ing and sowing the old vines are immedi- 

 ately turned under. Should these vines 

 have suffered from disease the previous 

 season, they would at once re-infect the soil. 

 As time goes on the land may become so 

 contaminated as to be unfit for sweet peas 

 for a number of years. To obviate this 

 the old vines should be burned as soon as 



