CLOVER AND ALFALFA DISEASES 
the disease. It is also recommended that 
where it becomes abundant prior to cut- 
ting any crop, the plants be mowed a little 
earlier than usual in order to save loss of 
foliage. 
This disease is seldom serious enough 
to warrant plowing up a field. Should it 
ever become so, rotation to other than 
leguminous crops should be resorted to. 
Root Nodules and Root Tubercles Upon 
Leguminosae 
Upon removal of the roots of the clover 
plant from the soil one finds minute en- 
largenients which are the subject of fre- 
quent inquiry. These are nodules or 
tubercles as they were formerly called, 
caused by the messmate-living of certain 
nitrifving organisms, or microbes, with 
the clover plant. To these microbes in 
this communal life is due the power of 
withdrawing nitrogen from the atmos- 
phere and fixing it in the tissues of the 
clover plants. The same applies in gen- 
eral to the nodules upon plants of this 
order, the Papilionaceae. It thus follows 
that these nodules are the normal condi- 
tion of properly nourished leguminous 
plants of the order Papilionaceae, and it 
likewise follows that the full value of this 
work of nitrogen fixing is only realized 
for manurial purposes when the tissues of 
the clover plants decay in the soil. 
Root Rot 
Fusarium roseum Lk.—Gibberella 
Saubineti (Mont.) Sacc. 
The same parasitic fungus which at- 
tacks wheat in the form of scab and also 
red clover, has been found killing out al- 
falfa. This fungus may survive in stubble 
fields where wheat and oats have been 
grown. It readily kills off the young 
seedlings of alfalfa and if the soil is not 
fully prepared for alfalfa seedings, the 
root-rot may extend its work and further 
destroy the stand. At present nothing 
better is known than adequate dressings 
of lime, preferably raw limestone, for 
areas to be seeded, together with their 
proper enrichment. While not specifically 
noted in America, another root rot fungus 
somewhat known on other crops (Khizoc- 
tonria) has also been reported upon alfalfa 
from France. Another root rot fungus 
821 
(Ozonium omnivorum Shear) well known 
upon cotton, also attacks alfalfa in the 
southwest. 
Rust 
Uromyces Trifolit (A. & 8.) Wirt 
The various sorts of the cultivated 
clover, red, alsike, mammoth, etc., are at- 
tacked by a clover rust. If one will ex- 
amine the small, dark spots in the clover 
leaves, he will find a cluster of this red- 
dish fungus beneath. This rust does not 
spread to other plants than clovers and 
is commonly regarded as more disfiguring 
than destructive. It is not nearly so in- 
jurious as the leaf spot of alfalfa which 
is similar in appearance. 
Stem Blight 
Fusarium roseunr Lk. 
Stem blight of clover has been found 
to be due to the same fungus as that of 
wheat scab. This fungus has been found 
to cause the death of seedling wheat plants 
and to follow harvest by attacks on clover 
stems. It appears at this time to be one 
of the serious forms of clover sickness. 
The writer looks upon it as liable to be 
much more serious even than anthrac- 
nose, The only present suggestion for 
control will apply to control of the wheat 
scab fungus through recleaning of seed 
and separation of all scab infected kernels. 
It is quite likely that clover seedings made 
in a dry year with little grain scab will 
not be exposed to the same danger from 
this blight as those made in wet seasons 
when the disease is very bad in the grain. 
A. D. SELBY 
Stem Ror. See Wilt, this section. 
Wilt or Stem Rot 
Sclerotinia trifoliorum 
H. S. JAcKSON 
The disease known as the alfalfa wilt 
is common. It was first described in Hu- 
rope but is also recorded in many widely 
separated sections of this country. It has 
been reported as serious in New York and 
California and has recently been found by 
the writer to be common in Oregon. It 
was first observed in certain fields in the 
Willamette valley. It is found to be most 
abundant and to spread most rapidly dur- 
ing the fall, when the surface of the 
