Family Cruciferae 193 



fies gelatine in about six days. Gas is produced with 

 a majority of strains. 



Control. The greatest loss in storage occurs where 

 the temperature is maintained much above the freez- 

 ing point and where the facilities for ventilation are 

 poor. To remedy this, the temperature, as far as possi- 

 ble, should be maintained one or two degrees above 

 freezing . The crop should be thoroughly dried and ex- 

 posed to the sunlight before being entered into storage. 

 Diseased fields should be rotated to other crops. 



DAMPING OFF 

 Caused by Olpidium brassicce (Worr.) Dang. 



The symptoms of damping off are similar to those 

 produced by Pythium de Baryanum, p. 43. The 

 sporangia of the parasite may be found singly or 

 in groups in each infected host cell. The zoospores 

 are globose, uniciliate. The resting spores are 

 globose, wrinkled, and star-like in appearance. 



The disease is found mostly in seed beds, where it 

 does considerable damage. For methods of control 

 see p. 43. 



WHITE RUST 

 Caused by Cystopus candidus (Pers.) Lev. 



White rust of cabbage is seldom troublesome 

 enough to attract attention. The symptoms of the 

 disease are the same as on other cruciferous hosts 

 such as mustard or radish, p. 211. 



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