H. C. Experiment Station 
15 
Precaution should be exercised both in the saving of seed from affected 
crimson clover fields and the planting of such seed because of its con¬ 
tamination with sclerotia. To guard against the introduction of stem 
rot into new fields or new localites, seed should be sampled and sent to a 
seed testing laboratory in advance of purchase. The introduction of the 
disease through manure from stock fed on hay from affected fields is 
also to he guarded against. 
It is known that not all host species are equally subject to attack by 
S. trifoliorum, but whether or not any one of these species possesses 
marked varietal differences in susceptibility is not known. Ho experi¬ 
mental work appears to have been done on selection for disease resist¬ 
ance and the only observation that has come to our attention that such 
differences exist is by Hilsson-Elile (17) who records that Swedish red 
clover of the variety serotinum is more resistant than exogenous strains. 
In fields badly infested no measures can be relied upon to be effective 
other than the adoption of a proper rotation system in which clovers are 
not grown for a period of three or four years. Definite data are wanting 
on the length of time which the stem rot organism can live saprophytic- 
ally in the soil, but it is logical to assume that it would no longer be 
present or the infective material would at least be greatly reduced in 
amount within a lapse of three or four years. Cowpeas and soybeans 
which are not subject to attack by Sclerotinia trifoliorum may well be 
used as a leguminous crop in such a system of rotation and winter oats 
and rye can be employed as winter cover crops. 
Summary 
1. Stem rot of clover is a fungous disease quite widely prevalent upon 
crimson clover within Hortli Carolina. 
2. Other kinds of legumes as red clover, white clover, alsike clover 
and alfalfa are subject to the same disease. 
3. Stem rot occurs in several states and has been known in America 
since 1890. It was present in England over one hundred years ago, 
where it caused failures of red clover and was popularly called clover 
sickness. The disease was first reported in continental Europe in 1857. 
4. The disease is prevalent from October to March and may be recog¬ 
nized by (1) a sudden wilting and death of plants in spots ; (2) a rotting 
off or decay of the stems near the surface of the ground; (3) the presence 
of black sclerotia on the decaying stems. 
5. The causal organism was first described in 1863 as Peziza ciborio- 
ides Fries. Since this was a mistaken identification it was in 1880 given 
the name Sclerotinia trifoliorum Erik, which name has been employed 
in the present account. 
