TOBACCO WILDFIRE IN 1922. 15 



by the laboratory air than by the out-of-door air where they are stored. 

 Sash are usually stored in a tobacco shed or barn, while the planks may 

 even be left out in the weather. The conditions in the shed are more favor- 

 able than the laboratory for the survival of the pathogen. (2) If sash are 

 kept in the tobacco shed, it is possible for diseased parts of the hanging 

 crop to become lodged on them. (3) If the plank are kept out of doors, 

 the moisture conditions would be about the same as for soil. In fact, the 

 bacteria might be alive in soil which remains attached to the plank. Since 

 we know that the bacteria can remain alive in the leaves and in the soil 

 over winter, there would seem to be no reason why the sash or plank would 

 not be a source of danger. Wolf and Moss (4: 32) and Fromme and 

 Wingard (3 : 22) have presented evidence to show that the germs may be 

 introduced into new beds by the use of old cloth covers which were pre- 

 viously used on infested beds. If such cloth covers or the tent covers used 

 in previous j^ars over wildfire crops are used, they should either be boiled 

 thoroughly in water or soaked in formaldehyde like the sash and planks. 



Spraying and Dusting Seed-beds. 



Results of the first experiment on the control of tobacco wildfire by 

 spraying or dusting the seed-bed have been published in Bulletin 203 of 

 the Massachusetts Agricultural Experiment Station. Subsequent to the 

 publication of that bulletin the experiment has been repeated at Amherst 

 four times, using a greenhouse bed 4 x 16 feet for each experiment. The 

 plants were pulled and counted when they were large enough for setting 

 in the field, and then the bed was seeded immediately for the next experi- 

 ment. The soil was not sterilized between experiments. The greenhouse 

 bed was used in preference to an out-of-door bed because in this way a 

 longer season could be secured and the experiment repeated more times. 



Some of the fungicides used in the first experiment were omitted in 

 later experiments because they were found to cause injury to the plants, 

 viz., sulfur dust, lime-sulfur and the Pickering Bordeaux. NuRexo was 

 used in the second experiment but omitted in the later ones, not because it 

 failed to give control, but because it was thought best to confine the tests 

 to one commercial copper spray. The copper-lime dust for the first ex- 

 periment was furnished by the Riches, Piver & Co.; the dust for the later 

 experiments by the Niagara Sprayer Company; the Pyrox was furnished 

 for all experiments by the Bowker Insecticide Company. In order that 

 all the data may be compared at a glance, the tables of results are first 

 assembled and presented here all together and then followed by the gen- 

 eral discussion. 



