DISEASES OF CULTIVATED PLANTS 389 
clover stems in meadows. It is apparently not a serious disease, althougha 
very interesting one to study in connection with the anthracnoses due to 
Colletotrichum. 
The third anthracnose upon clover (Colletotrichum cereale Manns.) is the 
anthracnose of wheat, rye and oats. It was found to a limited extent attacking 
clover upon the Station grounds in 1909. Except in microscopic characters this 
anthracnose cannot be distinguished from that of Bain and Essary first men- 
tioned above. In the microscopic characters the two are clearly distinguishable. 
It is quite probable that this fungus will be found over much of the state. 
Black-Spot is due toa fungus (Phyllachora trilfolii (Pers.) Fckl.) which 
attacks the leaves of clover causing dead spots and dark discolorations on the 
under side of the leaves. As a rule these attacks come so late in the working 
life of the leaves that the injury is slight. 
Dodders occur upon clover as well as upon the alfalfa; with it, likewise, 
there are two species (Cuscuta Epithymum Murr. and Cuscuta arvensis Beyr.), the 
seeds of which are distributed in the clover seed. In 1907-8 when the domestic 
- supply of seed ran so low the lack was made good by importations from Europe. 
This has brought a large amount of dodder into the state, the most of it being 
the clover dodder proper. With clover seedings as with alfalfa where infesta- 
tions are slight it will pay to dig up by root the infested plants and burn them 
for destruction of possible seeds. Dodder is a parasitic twining plant and may be 
easily recognized by its appearance. The seeds are illustrated in Bulletin 175. 
In the handling of the new clover seedings infested with dodder, ‘it is prob- 
ably best to clip in fall to prevent ripening of the dodder seeds. The hay crop 
may be cut the following season without fear since the seeds will not be in con- 
dition to grow. Following the mowing of the hay crop it is probably desirable 
to break the clover sod after the growth is fairly well started, and before time 
enough has elapsed to permit ripening of the dodder seeds. In no case is it 
desirable to cut seed from such dodder infested fields. Dodder in clover hay is 
held responsible for scouring of cows and horses. 
Leaf-Spot. A leaf-spot of white clover referable to an anthracnose fungus 
(Ascochyta sp.) has been described from our region although not definitely deter- 
mined in Ohio. The injury which may result cannot be now stated. 
‘Rust. The various sorts of the cultivated clover, Red, Alsike, Mammoth, 
etc., are attacked by a clover rust (Uromyces Trifolii (A. & S.) Wirt). If one 
will examine the small, dark spots in the clover leaves he will find a cluster of 
this reddish 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 injurious as the leaf-spot of alfalfa. which is similar in 
appearance. 
Root Nodules and Root Tubercles upon Leguminosae. Upon removal of the 
roots of the clover plant from the soil one finds minute enlargements which are 
the subject of frequent inquiry. These are nodules or tubercles as they were 
“formerly called, caused by the messmate-living of certain nitrifying organisms, 
_ or microbes, with the clover plant. To these microbes in this communal life is 
due the power of withdrawing nitrogen from the atmosphere and fixing it in the 
the tissues of the clover plants. The same applies in general to the nodules 
upon plants of this order, the Papilionaceae. It thus follows that these nodules 
are the normal condition of properly nourished leguminous plants of the order: 
FPapilionaceae, 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. 
