IG 

 Conditions Affecting the Spread of the Disease. 



1. Meteorological Conditions. Warm weather, combined with 

 excessive moisture both of the soil and of the atmosphere, and the 

 fact that transpiration is checked by this condition, undoubtedly play 

 an important part in the spread of the rot amongst cauliflowers and 

 turnips. Those seasons which are warmer and moister than the 

 average predispose plants to rotting. 



2. Rankness of Growth. The weather conditions above mentioned, 

 and the plentiful use of manure by market gardeners and good culti- 

 vation, favor very quick, rank growth. The plants most affected are 

 large and heavy, with many leaves shading the surrounding soil, 

 thus conserving moisture and promoting quick growth. 



3. Abundance of Insect Pests. The disease is chiefly spread by 

 means of infection by wounds, and under field conditions these are 

 usually produced by insects, especially the cabbage worm and turnip 

 beetle. A careful examination of" very many plants show that one or 

 more insects are present on each plant. Slugs also do considerable 

 damage. Ants and other insects swarm around turnips, eat the 

 rotting pulp and no doubt serve to carry the germs to other plants. 



4. Injury from Planting, Cultivation, or Wounds. Leaves of 

 turnips are frequently bruised or injured during cultivation by either 

 hand or horse hoes. Cauliflowers may be injured during planting 

 out and the infecting organism brought into contact with the broken 

 surface. In cases of very rank growth, heavy wind accompanied by 

 rain may cause leaves to be broken off and thus afford bacteria a 

 chance to penetrate into the plant tissues. Many gardeners trim 

 their cauliflowers on the fleld, and when these are infected they carry 

 the disease on to another season. The same ground is often used, 

 year after year, for the same crops, a dangerous procedure when 

 disease is present, as it is likely to carry over the trouble to other 

 years. 



5. Susceptibility of Varieties. Some varieties of turnips rot far 

 more easily than others. Thus, the Yellow Aberdeen Green Top, the 

 Yellow Globe, All Gold, etc., are usually far more rotted than a num- 

 ber of other varieties. 



Prevention. 



It is impossible to spray with any of the ordinary fungicides for 

 this disease as the organism is in the interior of the plant, and the 

 spray is only effective when it is actually brought into contact with 

 the organism ; hence spraying is of no use, and efforts are therefore to 



