EXPERIMENTS IN THE CONTROL OF POTATO LEAK. 5 
subject to leak than sound ones. That this view is erroneous is evi- 
dent from the results obtained in these experiments. Of the first 
lot, 6.25 per cent of the potatoes injured in this way became infected, 
while in the second and third lots the percentage was somewhat 
higher, being 8.5 and 9.5, respectively. The practices of removing 
these branches and of rubbing the raw surface in the soil, as is 
sometimes done, or sacking them, so that soil gets into the fresh 
wound, are harmful. If the broken surface is exposed to the air 
until the wound has had time to cork over, there is much less danger 
of infection. 
Not so many potatoes were wounded with the digging forks as by 
the removal of knobs, but the percentage of rotten ones among 
the fork-wounded tubers was much higher. Out of 1,000 sacks har- 
vested, 66 sacks were wounded with the digging forks. Of these, 
from 20 to 24.5 per cent rotted. The fact that the deep wounds 
made with the digging fork do not dry so readily and are more lia- 
ble to be filled with infected soil than wounds made by the removal 
of knobs seems to account for this higher percentage of infection. 
CONCLUSIONS. 
It is evident from these experiments that the sorting out of all 
wounded tubers would practically insure a shipment from damage 
by this disease. It is probable that it would be impracticable in 
commercial work to sort carefully enough to eliminate all the 
wounded tubers. A few wounded potatoes slipped through in these 
experiments in spite of the careful sorting. It is not difficult, how- 
ever, to remove 96 to 98 per cent of them. Such sorting, according 
to the percentages of rot occurring in the wounded tubers in these 
experiments, would result in an average of about one rotten potato 
in 10 to 25 sacks. This would be nearly complete control. 
It has therefore been demonstrated that the leak may be con- 
trolled by the elimination of all wounded tubers from the shipment. 
The best and most economical means of accomplishing this end would 
be to avoid wounding the tubers in harvesting them. Wounded 
tubers should be sorted out and shipped separately or, better, stored 
for a week or more to allow the fungus to incubate, and then sorted 
and the uninfected potatoes sold. 
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