Spraying Experiments in Nebraska 
61 
INCIDENTAL OBSERVATIONS 
At Brown ville in 1913, considerable summer pruning was 
done on plat 3. This consisted in the removal of dead and dis- 
eased wood and a general thinning out of the tops of the trees. 
At this time all blotch cankers which could be found were re- 
moved. To no other reason can be ascribed the difference in 
amount of blotch on plats 2 and 3. This difference, while not 
extraordinary, indicates what may be accomplished in this way. 
The greatest amount of infection seems to occur from about 3 to 5 
weeks after the petals fall. The exact time between these two 
dates depends upon weather conditions. Infection occurs more 
readily and abundantly if the weather is warm and moist. 
Blotch attacks fruit spurs as well as small branches and water 
sprouts. At the Hartley orchard, north of Lincoln, an exami- 
nation of a number of Mann apple trees revealed the fact that on 
two of these which were infected the worst, 20 per cent of the spurs 
were dead and on the remaining spurs more than 30 per cent of the 
buds were killed. This mortality could be attributed only to 
blotch injury, since the trees were otherwise in a good state of 
health. 
Grouped according to susceptibility as observed during the 
last three seasons, the common varieties rank as follows: 
Practically resistant Moderately resistant Susceptible 
Grimes (Golden) Lawver Mann 
York (Imperial) Ralls (Jenet) Missouri (Pippin) 
Winesap Minkler Maiden Blush 
Stayman Rome Northwest Greening 
Wealthy Arkansas (Mammoth Ben Davis 
Blacktwig) 
Arkansas Black 
This list is very short, owing to the lack of varieties in the 
orchards under observation. As in the case of resistance to scab, 
there was some variation of the comparative resistance of the 
different varieties. 
SUMMARY 
The results of experiments and observations during the past 
three seasons indicate that apple blotch on the fruit can be con- 
trolled entirely by spraying alone, but the eradication of the dis- 
ease may be facilitated by supplementing a thoro spraying cam- 
paign with the pruning out of affected wood. 
Bordeaux was found more effective than lime sulphur, but at 
the same time it was found to cause considerable injury to the 
fruit by russeting it. The injury was found to be greatest when 
Bordeaux was used at or soon after the time when the petals fall. 
