Spraying Experiments in Nebraska 
37 
generation may be started at several different dates and conse- 
quently produce their first crops of conidia at different dates. It 
is possible also that individual infections occurring at the same 
time do not all have the same period of incubation. Thus there 
may be a more or less constant appearance of scab, with the more 
pronounced jumps at intervals as indicated above. In fact this 
is what usually occurs. 
"The earliest infections usually occur on the lower side of the 
leaves. This is due to the fact that the lower side is more ex- 
posed at that time, while the leaves are unfolding. The later in- 
fections occur more abundantly on the upper surfaces, which by 
that time have assumed a more exposed position." 
During the cool, damp season of 1915 there was a great deal of 
loss due to secondary infection occurring from the latter part of 
July to the middle of August. To this late infection is attributed 
a large part of the loss in storage due to scab injury. It is quite 
possible that infection was taking place later than the middle of 
August. In fact the evidence indicates that infection was taking 
place just before the fruit was harvested, and that the storage scab 
resulted from this late infection, or, that it was caused, after 
harvesting, by infection from spores on the fruit at that time. 
The writer is of the opinion that infection occurred before picking, 
from the fact that some fruit heavily scabbed was stored in the 
same packages with clean fruit from an orchard free from scab, 
and when later removed for use, no scab appeared on the fruit 
from the clean orchard, altho the fruit was stored in the same 
cellar where so much infection was found. 
EXPERIMENTS IN 1913 
After reviewing the work already done on the control of apple 
scab, and carefully going over the situation in Nebraska, it was 
determined to use fungicides in connection with the regular cod- 
ling moth and curculio sprays but to leave them out of some of 
the sprays on certain plats. 
Careful observations were made of the time and amount of 
infection. Records were kept of all scab injury, however small, 
and of the amount of spray injury for each schedule. No uniform 
time of infection was found in the different orchards. Florence 
was the only place where rainfall was normally abundant early in 
the spring, and at this place the primary infection was heavy. 
The secondary infection was not heavy any place in the State. 
