INTERNAL BROWNING OF YELLOW NEWTOWN APPLE. 23 
browning will develop in fruit from over the district as a whole, or 
_ it may be so limited that browning will be practically unknown com- 
mercially during certain seasons. 
CONCLUSION. 
During the four years in which the present investigators have 
been studying this trouble, it has been found that seasons of very 
high crop production have been practically free from internal 
browning. During years when browning was prevalent the fruit 
from trees producing very heavy crops has been relatively much 
more nearly free from the trouble than neighboring trees that pro- 
duced light crops. On a single tree it has been possible, by heavy 
thinning and girdling of branches, to produce apples that tended to 
brown badly, while partial defoliation of well-loaded branches re- 
sulted in sound fruit. Heavy fertilization with manure tended to 
increase the percentage of browning, and heavy nitrogen fertiliza- 
tion increased browning markedly in all trees except those bearing 
a very heavy crop of fruit. 
Apparently under the growing conditions of the Pajaro Valley 
fruit tends to brown internally in storage when light crops of 
large coarse-textured fruit are produced. It is impossible for the 
orchardist to control weather conditions, and it is not always pos- 
sible to obtain a uniformly heavy crop on the trees. Internal 
browning apparently does not develop seriously, however, if storage 
temperatures are held at 36° F. or above. It is particularly im- 
portant that storage conditions be right during years of light crops 
and large-sized fruit. 
SUMMARY. 
Certain varieties of apples when placed in cold storage for a long 
season develop a brown discoloration in the flesh of the fruit which 
has been designated “internal browning.” This trouble is particu- 
larly serious in the Yellow Newtown apples grown in the Pajaro 
Valley district of California, where investigations have been car- 
ried on for a number of years. 
This trouble is not caused by a parasitic organism but appears 
to be brought about by certain conditions within the fruit itself. 
Apples from the Pajaro Valley have been found to be far more 
susceptible to this trouble than those from any other section of 
the country. This district has an extremely cool growing season 
coupled with high humidity and fertile soil conditions. 
Internal browning develops to a far greater extent in fruit held 
at 32° than that kept at 36° or 40° F. Its occurrence to an extent 
sufficient to be important commercially can be largely prevented by 
storing the Pajaro Valley apples at 36° to 38° F, 
? 
