CLOVER AND ALFALFA DISEASES 
Crown Gall 
Urophlyctis Alfalfae 
H. S. JACKSON 
This is a comparatively new disease in 
North America. It was first observed in 
this country in California in 1909, and 
has since been found elsewhere only in 
Arizona and Oregon. This disease was 
first called to the attention of the writer 
in May, 1911, when specimens of alfalfa 
crowns affected with this disease were 
sent in from Josephine county. Since 
that time it has been reported from a 
number of sections in Jackson and Jo- 
sephine counties. It is probable that the 
disease occurs also in other localities, but 
our atiention has not, as yet, been called 
to it. 
The disease was first described from 
Ecuador in 1892 and has since been re- 
ported from a number of sections in 
Europe, notably Germany, Bulgaria and 
England. 
So far as is known, the disease affects 
only the alfalfa. Experiments carried on 
in an attempt to grow it on clover and 
other plants have failed. 
Symptoms 
The disease is characterized by the 
formation of galls at the crown of the 
plant. The galls are more abundantly 
produced at the base of the stem, but may 
occur on the upper part of the root. The 
galls in some cases occur several inches 
above the ground on the stems. They 
present a very much roughened exterior 
and vary in size from that of a pea or 
smaller up to four or five inches in dia- 
meter. In form they are often confluent. 
Seriously affected plants are killed. 
Usually the disease will be found in the 
field in patches in which many of the 
plants are dead or in various stages of 
decline. The diseased plants are of a 
weak growth; the foliage is yellow and 
the leaves are reduced in size. 
Cause 
Crown gall of alfalfa must not be con- 
fused with the familiar crown gall of 
trees, small fruits, etc. It is not the 
same, and it is unfortunate that there is 
similarity in the common names. Crown 
2—I11 
817 
gall on trees and small fruits, as noted 
in another part of this report, is a bac- 
terial disease. 
Crown gall of alfalfa, on the other 
hand, is caused by a fungus of low order, 
known technically as Urophiyctis alfaifae. 
This is one of the Chytridiales, one of the 
lowest orders of Phycomycetes. In this 
group the mycelium is sparingly de- 
veloped. The presence of the fungus in 
the tissues, however, causes a stimu- 
lation which results in an abnormal de- 
velopment of the cells of the alfalfa at 
the point of attack. On the mycelium, 
resting sporangia are produced by a sim- 
ple sexual process. These are found in 
groups in small cavities in the tissue of 
the gall. These groups may be observed 
with the aid of a good hand lens, by mak- 
ing a cut through a fresh gall. The spor- 
angia are liberated by the rotting of the 
galled tissue and serve to spread the 
disease. When they germinate they pro- 
duce a@ number of small motile spores 
which cause the infection of new plants. 
It is probable that the disease has 
been introduced into the state through 
seed. It might be disseminated through 
alfalfa hay. It is possible that it might 
be carried some distance by the wind and 
might be spread locally from one part of 
a field to another or into new fields by 
accidental transfer of soil in which rest- 
ing sporangia are present or in which 
there are bits of decayed galls. This 
might occur from driving across a field 
in which the disease is present and car- 
rying the infectious material in soil on 
the wagon wheels or hoofs of the horses. 
Remedy 
No remedy is known. When the dis- 
ease becomes so serious as to render 
the field unprofitable, a rotation of at 
least three years’ duration to other than 
leguminous crops should be practiced. 
The disease might be prevented from 
spreading in a field, if the spots are ob- 
served soon enough, by a complete de- 
struction of the diseased plants. It 
might be advisable also to hoe the top 
soil toward the center and thoroughly 
spray the ground with copper sulphate 
or Bordeaux mixture. AS a general pre- 
