Jan. 34.1916 
Sweet-Potato Scurf 
791 
as the cause of the disease. In view of these facts, it is believed prefer¬ 
able to give it a description and permit it to maintain generic rank rather 
than to place it in a genus where it does not naturally belong. 1 
Monilochaetes 
Hyphae dark, erect, rigid, septate, not in definite fascicles; conidia distinctly differ¬ 
ent from the sporophores and hyphae, hyaline, slightly brown with age, continuous, 
not in chains, acrogenous. 
Monilochaetes infuscans 
On the host definite vegetative hyphae are lacking; sporophores septate, erect, un¬ 
branched, dark, and attached to the host singly or by twos, by a bulblike enlarge¬ 
ment 40 to 175/i long, 4 to 6 {jl wide, bearing rarely a hyaline one-celled oblong spore. 
In cooked rice the hyphae are much branched, septate, brown; sporophores brown ex¬ 
cept at terminal cell, which is frequently hyaline to slightly brown, septate, branched, 
stout, 30 to 225 by 4 to 6/*; conidia abundant, one-celled, hyaline, ovoid to oblong, 
12 to 20 by 4 to 7ju, solitary, terminal. 
Parasitic on the underground parts of Ipomoea batatas . Type specimens deposited 
in the pathological collection of the herbarium of the United States Department of 
Agriculture, Washington, D. C. 
SUMMARY 
The scurf disease of the sweet potato was first recognized in 1890 by 
Halsted, who named the fungus “Monilochaetes infuscans ,” a new genus 
and species. He failed, however, to describe either the genus or species. 
The scurf has been found prevalent in nine States and sparingly in others, 
and on 16 varieties of sweet potatoes. The organism has been shown by 
inoculation experiments to be the true cause of the disease. A detailed 
discussion of the morphology of the organism is taken up, also its growth 
on different culture media at different temperatures. It was found that 
the organism on the host consisted merely of sporophores and conidia. 
In culture, however, well-defined branched mycelia and spores developed. 
1 The writer is indebted to Dr. C. L. Shear and Mrs. Flora W. Patterson, of the Bureau of Plant Industry, 
for having examined specimens of this fungus. 
