A SERIOUS LETTUCE DISEASE. 
133 
In Kentucky, 11 a drop* is reported to have been checked by sub¬ 
irrigating and placing a mulch of excelsior under the plants to prevent 
their touching the soil. 
Fig. 29.—Steaming the soil by means of Sargent’s sterilizer. 
To test the applicability of the above well-known methods to the 
cold frame and field conditions of the South, numerous experiments 
were planned and carried out at Kew Bern and West Baleigh, some of 
which were as follows: 
Experiment 3. To test the efficiency of soil disinfection by heat. 
One-half of a bed designated as Bed A was prepared by laying 2-inch 
drain tile 10 inches deep and about 13 inches apart with the ends 
Fig. 30.—Showing the arrangement of tile in box used for steaming the soil for top dressing. Ends 
of tile, b, were closed with cement. 
all running into cross tile as shown in Fig. 30. Thermometers were 
placed in the soil, care being taken not to place any of them over the 
rows of tile. 
*It is uncertain whether this was sclerotiniose or some other form of drop. 
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