INSECTS AND DISEASES IO3 



on the bulbs before they are pulled, especially if they 

 have been weakened from any cause, and among the 

 housed onions it propagates itself with a severity 

 proportional to the favorableness of the conditions 

 offered it for the formation, dissemination and ger- 

 mination of its spores above described. These con- 

 ditions are warmth and moisture, and the proximity 

 of uninfected bulbs. It may be communicated by 

 contact with diseased bulbs or with any object, such 

 as the hands, or tools that have been subjected to such 

 contact, and may be also spread by strong drafts 

 which blow about the spores or dry scales containing 

 them. 



The most important precaution which can be 

 taken against the disease consists in housing the 

 onions during dry weather after the bulbs are thor- 

 oughly dried off. No bins which have contained such 

 black onions should be used a second time, until they 

 have been thoroughly cleaned and sprinkled with quick- 

 lime, or quicklime and sulphur. All danger of heat- 

 ing should be avoided, and the onions stored in as 

 cool and dry a place as possible, which can be arranged 

 to be ventilated in dry weather and shut up when the 

 atmosphere is moist. Should the fungus be noticed 

 on the bulbs at the time of storing, or in any case 

 when there has been previous damage from this cause, 

 it is probable that a treatment with dry air-slaked 

 lime, such as has been recommended with success for 

 potatoes (one bushel of lime to twenty-five bushels 

 of onions), applied at the time of storing, would 

 prove of great service in checking the spread of the 

 fungus. The utility of this practice, however, needs 

 confirmation by actual experiment before it can be 

 definitely recommended. In any case, such treatment 

 should be made at the outset^ since it would have 



