KERX EL-SPOT OF THE PEC AX AXD ITS CAUSE. 
13 
It is logical to conclude that greater vigilance in protecting the 
pecan crop from kernel-spot will have to be observed during seasons 
following winters with no extremely low temperatures, as there will, 
no doubt, be a lower mortality of hibernating bugs. 
While the information leading to an explanation of the irregular 
appearance of kernel-spot is meager, it is significant to record that 
two very severe occurrences of the trouble have followed winters 
with no extremely low temperatures. 
There Avas a greater occurrence of kernel-spot during the seasons 
of 1916 and 1921 than during any other years on record for southern 
Georgia, while in this same region there was very little kernel- 
spot during the seasons of 1917, 1918, and 1919. 
Table 4 shows the absolute minimum temperatures recorded by the 
United States Weather Bureau at Thomasville, Ga., covering the 
period from 191-1 to 1921. inclusive, together with the prevalence of 
kernel-spot. 
Table 4. — Minimum temperatures and kernel-spot prevalence at Thomasville, 
da., J!)!-' f io 1921, inclusive. 
Years. 
Mini- 
mum 
tem- 
pera- 
ture 
(°F.)- 
Prevalence of kernel-spot. 
1914-15 23 Abundant. 
1915-16. 25 Do. 
1916-17. 13 Small amount. 
Do. 
Mini- 
mum 
Years. 
tem- 
pera- 
ture 
(°F.). 
1918-19. 
18 
1919-23. 
23 
1920-21. 
29 
Prevalence of kernel-spot. 
Small amount. 
Abundant. 
Do. 
The correlation of kernel-spot with temperatures may be only a 
coincidence. However, it is the writer's opinion that future obser- 
vation will establish a record showing relationship of occurrence of 
kernel-spot with winters of no extreme low temperature. 
While this investigation seems to clearly demonstrate that the 
inciting cause of pecan kernel-spot is due to insects, the pathological 
and physiological changes involved are apparently influenced by the 
condition of the nuts at the time the punctures are made. Bugs, 
confined in cages with mature pecan kernels that had been removed 
from the shells, were observed for several days by the writer. The 
bugs fed upon the kernels constantly, but produced no evident in- 
juries or spots resembling kernel-spot. This suggested that spots 
can be produced by the bugs only when the tissues of the kernels are 
soft and the cell walls can easily be ruptured by the sucking effect 
of the insects involved. 
The history of the investigation of pecan kernel-spot and its path- 
ological effect upon the host plant is parallel in ways to the disease 
of carnation leaves that Woods (#) designated as stigmonose and 
proved by him to be caused by punctures of aphids, thrips, and red 
spiders. This carnation trouble had previously been studied by 
