~ 
GAS TREATMENT FOR TOBACCO o 
ment too long, particularly when one muslin is to be used on several 
beds. In general, it is advisable to begin as soon as the disease appears 
in the vicinity and to follow some regular schedule, because growers are 
often too busy to be able to keep disease developments under close 
observation and these developments sometimes occur with unexpected 
rapidity. The number of treatments required per week will vary 
somewhat with conditions and localities. When blue mold is active 
under very cool conditions, as is often the case in Georgia, 3 treatments 
a week are advisable, and in beds where considerable disease is present 
at the start, treatment on 2 or 3 consecutive nights is desirable. 
Generally 2 treatments a week are adequate, and these should be so 
spaced as not to have more than a 4-day interval between treatments 
during periods when the disease is active. Treatments should con- 
tinue as long as protection is required. In different sections and years 
the period during which protection has been required has varied from 
2to8weeks. In general, from 5 to 10 treatments have been sufficient. 
Preparation of Plant Beds for Treatment 
Preparation of narrow beds (2 to 3 yards wide, with board side walls 
6 to 12 inches high).—If narrow beds are constructed with tight-board 
side walls, they can be prepared for gas treatment in a variety of ways. 
An important point to remember in such preparation, however, is that 
if the paradichlorbenzene is scattered over the tobacco cloth this must 
be well above the plants, because if either the cloth or the cloth and 
the muslin are permitted to sag down close to the plants, injury may 
be expected. If the side-wall boards are 10 to 12 inches high, then the 
cloth can be stretched flat across the bed with suitable cross supports 
about 5 feet apart. However, if the side-wall boards are 6 to 8 inches 
high, then a center ridge at least 15 inches high must be constructed to 
give sufficient overhead room. In general, it is most convenient to 
fasten the cloth with lath strips along one side and weight it on the free 
side with boards, poles, or 4-inch pipe. Also, a wire along the free side 
or a detached cover with wires on each side will work well with board 
beds, although these methods were developed particularly for use with 
log beds. An arrangement to roll the heavy muslin cover on and off 
the bed is advantageous, and this can readily be done with the aid of 
pipe or slender poles, provided the bed or bed section is not over 50 feet 
long. 
Preparation of log beds —Probably 85 percent of the plant beds in 
Georgia, South Carolina, North Carolina, Virginia, and Maryland, 
where blue-mold control is of major interest, have log sides and are 
from 5 to 10 yards wide. Such beds ean be treated effectively with 
paradichlorbenzene, and the preparations required are simple and 
inexpensive. Figure 2 illustrates one system. The muslin cover is 
prepared by sewing a fold in the cloth on either side and running a 
heavy wire with loops at each end through these two folds. Four 
straight iron stakes three-fourths inch thick are provided for the 
corners, and eight clamp stakes one-half inch thick are used to hold 
the cloth down on the two sides. ‘The first step in preparing a bed for 
treatment is to line up the logs and anchor them with a few wooden 
stakes. Then openings on the under side are filled with earth. Next, 
rows of stakes about 5 feet apart are placed in the bed and wires are 
stretched both ways. Occasional rigid wood suppor ts are also helpful. 
In the center of the bed the wires should be 18 inches above the soil 
Ne NA o> ANION NOONN ANON MON OMANI :_L AAA AAAEA_ | LAHQ’G’AAN AAT TTA AATTEAAAAM Qe _QQnn 
