FUMIGATION OF CITRUS PLANTS. De 
MOISTURE. 
Experiments 4, 6 to 9, and 11, were performed with both dry and 
wet plants. A comparison of results of these experiments has been 
presented under the paragraph treating on prefumigation influences. 
It was found that moisture on plants in prefumigation shade or 
darkness in no way affects the results where the fumigation is per- 
formed in shade or darkness. However, where plants were in sun- 
shine before fumigation it appeared that a wetting with cool water 
tended to reduce the injury below that normal to dry plants. 
TEMPERATURE. 
Temperature is a factor of much concern during actual fumigation, 
and has already been discussed in this paper. Its influence is so 
modified by the prefumigation and postfumigation temperature and 
light conditions that it is necessary to pay full attention to these two 
latter environments in determining the temperature of safety during 
actual gas exposure. The experiments included in this paper in 
which plants were at no time exposed to the sunshine, and in which 
the prefumigation and postfumigation temperatures were within the 
range of optimum heat conditions, exhibited very little injury where 
plants were fumigated at temperatures below 80° F. In some experi- 
ments in which the temperature of fumigation exceeded 80° the 
injury appeared to be little if any more severe than at lower temper- 
atures of fumigation, provided the prefumigation and postfumigation 
temperatures were both low; in other experiments the injury appeared 
to be greater at the higher temperatures of treatment. When, how- 
ever, either the prefumigation or more especially the postfumigation 
temperature was high as well as the actual fumigation temperature 
the injury was, in general, noticeably more severe than at cooler tem- 
peratures. This is well illustrated by a comparison of experiment 1 
with either experiment 14 or 15. Unfortunately none of the experi- 
ments performed at temperatures exceeding 80° F. were held at a 
uniform heat throughout the exposure, but the temperature fluctu- 
ated at least several degrees after the plants were inclosed in the 
fumigatorium. This condition introduces a secondary factor which 
must be taken into consideration in drawing conclusions as to the 
effect of high temperatures on plant injury. 
It appears from a comparative study of the experiments in this 
paper that severe injury is most noticeable where any two or all 
three of the fumigation environments, prefumigation, fumigation, 
and postfumigation, are at high temperatures. In short, if the actual 
fumigation temperature is high, a minimum of injury is likely to fol- 
low if both the other environments are cool. If, however, either the 
prefumigation or more especially the postfumigation temperature is 
also high, much more severe injury is likely to result. The evidence 
