May 19,1923 
Spores in the Upper Air 
605 
they probably are blown long distances. Just how far they are blown 
and just how important they are in starting rust far from the place 
where they were produced can not be stated definitely. More observa¬ 
tions will be made. 
The airplane is a great aid in studying the distribution of spores of 
pathogenic fungi. It is likely to be very useful in epidemiology studies 
and it also may be useful in determining the value of establishing 
quarantine lines. 
SUMMARY 
(1) In the spring and summer of 1921 spore traps were exposed on 
airplanes at various altitudes and at several places in the Mississippi 
Valley. 
(2) Many spores of several different genera of pathogenic fungi, coni- 
diophores, pollen grains, glumes of grasses, and small insects were caught 
on the slides. 
(3) Spores and pollen grains w^e relatively abundant at altitudes up 
to 11,000 feet. They were relatively scarce at higher altitudes, but two- 
spores of what appeared to be Puccinia triticina were caught as high as 
16,500 feet. 
(4) Altemaria spores which were caught at altitudes of 10,500 feet and 
less were viable; urediniospores and aeciospores of PtLCcinia graminis, 
caught at elevations of 7,000 feet and 1,000 feet, respectively, also 
germinated. 
(5) Airplanes probably will be useful in studying the dissemination of 
spores of many pathogenic fungi, and probably will aid in the solution 
of problems connected with ^e development of epidemics of plant 
diseases. 
