Jan. io, 1914 
Some Diseases of Pecans 
337 
on the apple bitter-rot it is thought that Bordeaux mixture will prove 
effective. Some indications of difference in varietal resistance have been 
observed. High temperature and humidity furnish the optimum condi¬ 
tions for growth and spread of the disease, as is the case with the bitter- 
rot of apple. 
The kernel-spot is fortunately rare, but on this account the present 
study has been largely confined to laboratory and greenhouse work. 
The fungus Coniothyrium caryogenum , n. sp., causes the development of 
dark brown to almost black surface spots upon the kernel. Internally the 
diseased tissue extends in an approximate hemisphere beneath the dark- 
colored spot and is pithy in texture and bitter to the taste. Pure-culture 
inoculations have been largely successful. The optimum temperature for 
growth was found to be about 70° F. The mycelium enters the cells of 
the kernel, where it is often more or less swollen and broken up into its 
constituent cells. Pycnidia have been produced abundantly in culture, 
but on the host only on the extracted kernels in a damp chamber. 
Crown-gall has been found on the pecan in northern Florida and 
southern Mississippi. It is similar in appearance to the well-known 
crown-gall of plants and has been shown by pure-culture and inoculation 
work to be due to the same organism, Bacterium iumefaciens Sm. and 
Town. 
