POTATO DISEASES IX HAWAII. 15 
may be necessary. Potatoes carefully graded as to size are much 
more readily sold at a good price than when large and small are 
mixed. All potatoes of inferior size should be soiled out and used 
on the farm. It is a poor policy to leave in the shipment any bruised 
or decaying tubers, as these are valueless and by wetting and other- 
wise making the lot unattractive they may result in considerable loss 
to the shipper through market charges for re-sorting. 
Outside the cold-storage warehouses a sufficiently cold place for 
the storage of potatoes is difficult to maintain in Hawaii. For the 
best results a temperature of about 35° F. is required. It is probable 
that houses quite suitable for the storage of this crop could be con- 
structed at the higher altitudes where potatoes are most successfully 
grown should there develop sufficient economic advantage in holding 
the crop. Since the potato consumption in the islands is so greatly in 
excess of the production, there is little incentive to store. However, a 
small storage place, screened against insects, tightly built, and pro- 
vided with close-fitting doors, so as to take advantage of the night 
temperature, would be valuable in preventing loss from shipping to 
a glutted market. The place could be used for holding seed stock, 
for fumigating and storing beans, corn. etc. 
POTATO DISEASES KNOWN TO OCCUR IN HAWAII. 
CLASSIFICATION. 
In order that plant diseases may be intelligently combated, an 
understanding of their nature is necessary. According to their 
causes the diseases to which the potato is subject may be divided into 
two classes: (1) Those caused by organisms, as fungi, bacteria, in- 
sects, etc.. which may be called parasitic diseases: (2) those induced 
by unfavorable growing conditions or by obscure and undetermined 
causes, which may be termed nonparasitic diseases. 
The parasitic organisms which cause diseases of the first group 
may be present in the soil, introduced on the seed, or brought to the 
soil and the growing crop from adjacent fields by wind or water., 
Under favoring conditions in the presence of the potato plant, the 
disease progresses more or less virulently. The following parasitic 
diseases, grouped according to the nature of the parasite as fungus 
or insect, have been found factors in potato production in Hawaii: 
Fungus diseases, including Fusarium wilt {Fusarium oxysporum), 
late blight (Phytophthora infestans). black scurf and rosette {Rhiz- 
octonia solan i). early blight (AUernaria solani). common or corky 
scab {Actinomyces chromo genus), tuber rots {Fusarium oxysponun. 
F. radicicolO) and F. coeruleum) : insect pe>ts. including tuber moth 
{Phthorimcea operculeUu). cutworms and a similar leaf-eating worm 
