POTATO DISEASES IN HAWAII. 41 
CONCLUSION. 
The growing of Irish potatoes in Hawaii, though an industry of 
considerable importance, has been largely discouraged in recent 
years by persistent crop failures and unfavorable marketing condi- 
tions. It is desirable that the islands become self-supporting so far 
as possible with respect to this commodity. It is believed that the 
potato crop can be doubled without any increase of acreage by the 
adoption of modern agricultural methods. 
Crop failures, which have been found to be a persistent source of 
loss, are brought about by the following factors: (1) The use of poor 
seed, (2) continuous cropping (as many as three or four crops a year 
with no systematic rotation for a half century or more), (3) diseases 
and insect pests, and (4) unsatisfactory soil conditions. Fundamen- 
tally the diseases have been the most important factor, with the other 
mentioned factors as contributing causes. 
The diseases, so far as they have come to the attention of the writer, 
have been determined, and recommendations have been made for their 
control, both through the improvement of cultural practices and 
through special methods where required. Certain diseases which are 
destructive in other localities but have not yet been found here are 
described in order that their introduction may be the better guarded 
against. 
The following diseases and pests of the Irish potato have been 
found to occur in Hawaii: Fusarium wilt (Fusarium oxysporum), 
late blight (Phytophthora infestans), early blight (Altemaria 
solani), black scurf and rosette (Rhizoctonia solani), Sclerotium 
wilt (Sclerotium rolfsii), common or corky scab (Actinomyces 
chromo genus) , tuber rots (Phytophthom infestans, Fusarium oxy- 
sporum, F. radicicola, and F. coeruleum), tuber moth (Phthorimaea 
operculella) , cutworms (and a similar leaf-eating worm locally called 
"poko"), mite disease (an unidentified form of Tetranychidae) , 
nematodes (Heterodera sp.) ; and the nonparasitic troubles sunscald, 
sunburn of tubers, leaf tipburn, hollow potato, pronged potatoes, 
arsenical injury. 
The universal adoption of the practices of seed selection and dis- 
infection, crop rotation, and spraying with Bordeaux mixture are 
recommended for the general improvement of the potato situation. 
Only through the use of healthy, vigorous seed and fertile, disease- 
free soils, maintained through crop rotation, can healthy crops be 
secured. When once healthy plants, in other words, plants worth 
saving, are assured, the value of Bordeaux mixture in preventing 
late blight, the most serious potato disease in Hawaii, will be more 
readily seen, and under improved cultural conditions spraying will 
