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process would be beneficial. Ice nucleatlon-actlve bacteria would be removed 
efficiently from the atmosphere by nucleating and being Incorporated Into 
supercooled water droplets, thus facilitating their removal from the upper 
atmosphere before viability was lost In the harsh environment of the 
atmosphere. Therefore, ice-nucleatlon activity could have evolved as a factor 
increasing the efficiency of distribution of these bacteria via atmospheric 
transportation processes. In addition, by Increasing precipitation or altering 
precipitation patterns, these bacteria may have improved plant growth or 
environmental conditions on plant surfaces to allow better survival or growth 
of Ice-rucleatlon-active bacteria on plants (Sands 1981). (T) 
The modified INA” bacteria are subject to dispersal into the atmosphere In 
the same manner as wild INA" and INA* bacteria. The modified INA" bacteria to 
be released in this field test will be no more competitive than their wild 
counterparts and, because of their limited numbers, will not have an effect on 
whatever balance exists between INA* and INA" bacteria on plants in nature. 
There is no evidence that INA’ bacteria displace INA* bacteria in the 
atmosphere. Only in the unlikely event that INA" bacteria were to displace 
INA* bacteria over large areas of the world's vegetation could any impact on 
INA* populations in the atmosphere occur. Routine agricultural practices such 
as cultivation, pruning, application of pesticides and herbicides, land 
clearing and burning remove many times more INA* bacteria from vegetation than 
the numbers that might be prevented frotp colonizing plants by these proposed 
field tests. No change in weather or climate has been attributed to these 
other man-made changes in INA* bacterial populations. Since the survival time 
for bacteria in the atmosphere is limited and INA* bacteria have much greater 
ice nucleating ability than INA’ bacteria to form precipitation droplets to 
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