58 Diseases of Truck Crops 



shotald be taken to prevent the seedlings from be- 

 coming "drawn,'.' for at that stage they are most 

 stisceptible to damping off. The safest plan is to 

 keep the temperature a trifle lower than is gener- 

 ally required, and .allow as much ventilation as 

 possible. Very often damping off starts in one 

 comer of the bed. To check the rapid spread of the 

 disease, the infected area may be removed. Spray- 

 ing the seedlings with various fungicides in a bed 

 where damping off has become well established wiU 

 be of little help. 



Control of Fusakium- and Nematode-Sick Soils 



The formaldehyde or the steam sterilization meth- 

 ods which are so effective in the treatment of sick 

 seed beds cannot be used on a large scale for sick 

 soils on account of the extensive cost involved. The 

 trucker, therefore, must resort to other methods of 

 control. Soils which are made sick by the presence 

 of parasitic fungi or nematodes may be reclaimed by 

 crop rotation as well as by the development of wilt- 

 resistant varieties. Both of these methods will be 

 discussed at length in pages 372, 373. 



Control of Insect-Infested Soil 



Spraying the soil will be of little value in the control 

 of underground insect pests. Fortunately, however, 

 we have more effective means for dealing with them. 

 To destroy wireworms, sow com which has -been 



