December, ’20] WOGLUM AND ROUNDS: DAYLIGHT ORCHARD FUMIGATION 485 
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severe injury, and particularly was this true for lemons, which appear 
to be far less susceptible to sunshine fumigation than are oranges. 
On the other hand parts of orchards would sometimes be greatly 
injured even with a dosage and exposure in no way severe to the same 
varieties in the adjoining orchards. Such differences in injury are 
attributable to varying soil conditions and the physiological condition 
of trees, and in this we find one of the greatest drawbacks to daylight 
work, for it appears to intensify injury to trees least resistant to gas 
to a much greater extent than does night practice. 
Conclusions 
The writers have carried on experimental daylight fumigation with 
liquid hydrocyanic acid from the middle of the active fumigation sea¬ 
son in October throughout the winter period. As a result of this work 
they are convinced that, where practicable, daylight winter fumigation 
is preferable to night work. At this period the insects are especially 
difficult to kill on cool nights. Furthermore, the trees are in a dormant 
■condition and can withstand a stronger gas even at temperatures 
approximating 80° F. Particular attention should be given to the 
exposure. 
While the data accumulated during the past season shows that an 
experienced and careful operator with a few tents can by constant 
manipulation of dosage and exposure practice daylight work during 
the growing season, especially on lemons, with partial success, such 
practice in preference to night work cannot be recommended at the 
present time. Experience has proved that fixed dosages and exposures 
.are the safest guides to effective fumigation and the necessary data 
has not yet been accumulated to establish this condition for daylight 
summer and autumn work. In fact there is considerable doubt if a 
fixed dosage-exposure combination can be developed which is practical 
under the extreme varieties of daylight weather during the usual 
fumigation season, a situation which is further emphasized by the 
widely differing conditions between the hot interior valleys and the 
cooler, more humid coastal belt. 
Chairman A. L. Melander: We are now prepared to show you 
three reels of motion pictures illustrating “ Beekeeping in the National 
Forests,” by G. A. Coleman. The pictures were screened by the chair¬ 
man. 
Chairman A. L. Melander: The final part of the program will be 
eoncluded by Prof. Trevor Kincaid who will briefly discuss “The 
Earwig Problem About Seattle.” (No report was made of this talk 
by the Secretary.) 
