52 
Journal of Agricultural Research 
VoL XXV, No. a 
and of the inoculated hill, are shown in Plate 3, A, B. It seems probable 
that the spindling-tuber disease (p. 55) was introduced into all three 
tubers of the inoculated hill, while leaf-rolling mosaic was introduced 
into only two, both diseases being manifested when in combination as 
mottled curly-dwarf (47, PL 2; 32 , PL 13). 
Intervarietal inoculations, described later, transmitted leaf-rolling 
mosaic alone to Green Mountains (PI. 2, C 1). 
RUGOSE MOSAIC 
A type of mosaic much more infectious than mild mosaic, as will be 
shown later, is further differentiated by distinct dwarfing, more chlorosis 
and more diffused mottling, a more rugose type of wrinkling, and a tend¬ 
ency to show brittleness, spotting, streaking, leaf dropping, and prema¬ 
ture death (PI. 1; 3, C, 1; 4, A, 1), especially when in combination 
with the spindling-tuber disease. It is equivalent in part to the medium- 
plus mosaic of the writers* previous publications (40, p. 316). The tuber 
symptoms are a marked reduction in size. 
The writers believe that most of Murphy's crinkle (29, p. 71-74 ), is 
identical with the type here designated as “rugose mosaic** with some 
leaf-rolling mosaic symptoms included by Murphy. It is probable that 
the name “crinkle** is more descriptive of this disease in a large number 
of varieties, because of the mottling being generally masked, but the 
facts, first, that there is mottling, and, second, that the masking of mosaic 
is generally realized to be fairly common, make it seem unnecessary to 
abandon here the well-known term “mosaic.** The symptoms of 
“crinkle'* as given by Atanasoff (4, p. 13-16) include “ a heavy mosaiclike 
variation in color,** which can serve very well to describe the writers* 
“rugose mosaic.** This type of mosaic in some varieties (42) and in 
some combinations (14) produces an extreme form known as “mosaic 
dwarf.** “Mosaic dwarf,** however, as suggested by Krantz and Bisby 
(21 , p. 7), seems to the writers to contain more than one disease or symp¬ 
tom-complex. A current-season or primary symptom of crinkle is 
leaf dropping (59, p. 139 ), which is also a symptom of other degeneration 
diseases and combinations. Rugose mosaic is more infectious, or at 
least more generally conspicuous, than mild mosaic in varieties in the 
Cobbler, Rural, and Rose groups (48) and perhaps others (45, p. 249), and 
also is more common in southern regions than in northern. 
It is thought probable that the striking current-season symptoms re¬ 
ported for mosaic leaf-mutilation inoculations in the open field in 1919 
(40, p. 320-23) were involved with the rugose type of mosaic. Inter¬ 
varietal transmission to Green Mountains was effected in 1920 and 1921 
(P- 66). 
Leaf-mutilation inoculations with rugose mosaic were made in the 
Orono, Me., greenhouse in the winter of 1921-22, in eight hills from four 
tuber units. The sources of inoculum were three hills that were progeny 
of field-grown plants with streaking but, in one case, with no mottling, and 
showed dwarfing, mottling, wrinkling, spotting, burning, and leaf dropping. 
Of the inoculated hills, two showed leaf dropping in 17 days, five in 24 
days, and one in 42 days, and one showed mosaic in the uppermost leaves. 
Most of the progeny (17 of 18) of the inoculated hills, when grown in the 
same greenhouse in thef olio wing summer, were mosaic, completing the con¬ 
trast to parallel inoculations with mild mosaic where no symptoms ap- 
