12 BULLETIN 64, U. S. DEPARTMENT OF AGRICULTURE. 
sole, cause of the early maturity and diminished harvests. This tule 
land for potatoes commands a cash rental of $20 to $25, while for 
barley growing only $8 to $12 is paid, but after the second crop of 
potatoes the less profitable crop must intervene (Irish, 1913). 
One of the leading potato districts north of California is the Willa- 
mette Valley, in Oregon. Here wilt is present to a serious extent. 
During visits in 1909 and 1910 the writer saw fields fiber ally dotted 
with yellow and dying plants. This valley furnishes most of the 
seed potatoes brought into California, and inspection of such potatoes 
has revealed much stem-end browning. 
It is certain that the Fusarium wilt is a nation-wide problem and 
one that will have a marked influence upon American agriculture. 
At present it causes losses which probably run into millions of dollars; 
but, if in the end the growers are forced to adopt better rotation 
systems, who shall say that the final influence of this disease factor 
may not be beneficial ? 
Estimates of the money losses from Fusarium wilt must be largely 
speculative, as so little exact information is available. At the Ohio 
experiment station in 1909 the result of the disease was that '"'the 
station plats averaged 69 bushels per acre and the county averaged 
186 bushels. The preceding 4-year average for the station was 180 
bushels, while that for the county was 101 bushels." The county 
was also infected with wilt, as the same writer shows; but, disregard- 
ing this and the fact that the station yield should have been nearly 
double the county yield, and estimating that only 5 per cent of Ohio 
fields were as badly affected, the loss totals over 870,000 bushels for 
Ohio alone. 
CONTROL OF FUSARIUM WILT. 
The problem of control has not yet been worked out for Fusarium 
wilt. The most promising lines of attack are three: (a) A healthy 
seed supply, (b) rotation of crops, (c) the development of resistant 
varieties. 
The use of Fusarium-infected seed should be avoided even where 
the disease is already in the land. It not only increases the severity 
of the wilt trouble, but gives defective germination. Failures due to 
decay of the seed potatoes after planting are especially frequent in 
the West, as, for example, in Colorado in 1908 and in California in 
1912. These are attributed to Fusarium, but the recent studies of 
Wollenweber show that Fusarium oxysporum does little more than 
lower the vitality and afford an entrance for other organisms 
which destroy the seed potatoes after planting. F. trichothecioides 
in the West and F. coeruleum in the East are the best known of these 
tuber-decay producers. To what extent other organisms are involved 
remains to be determined. 
