Apr. 26, 1924 
Studies on Curly-Top Disease of the Sugar Beet 
305 
Table IV. —Artificial inoculations of sugar beets, resulting in no disease —Contd. 
Date 
Kind of inoculum 
Kind and number 
of plants 
inoculated 
Season of 1919— 
Continued. 
August 8 .... 
Entire viruliferous leafhopper. 
Seven young 
beets. 
August 13 __ 
Two entire curly-top plants 
macerated in distilled water. 
Three young 
beets. 
Do... 
Part of the preceding extract. 
Several young 
plants. 
August 27 _ . 
Distilled-water extract of two 
entire curly-top beets. 
S everal beet 
plants with 
roots one-fourth 
inch in diame¬ 
ter. 
October 2-.. 
Pieces of midrib of badly af¬ 
fected leaf of a curly-top 
beet. 
One young beet-- 
Do. 
Piece of midrib of curly-top 
beet leaf. 
One beet seedling- 
Do. 
A leafhopper nymph from a 
curly-top beet. 
One young beet.— 
Do.. 
Adult leafhopper from a curly- 
top plant. 
One beet seedling.. 
Do. 
Entire viruliferous insect. 
Three beet plants 
with i-inch roots. 
October 18- 
s 
Small piece of petiole of a leaf 
of a curly-top beet. 
Three young beets. 
October 21 ~ 
Season of 1920: 
Tops and roots, of curly-top 
beets separately extracted in 
distilled water. 
Eight plants with 
finch roots. 
April 27...- 
Extract of entire curly-top 
plant in distilled water. 
Several beets. 
May 2_. 
Tap-water extract of two en¬ 
tire young curly-top beets 
which had been macerated 
in a mortar. 
Three young beet 
plants 
May 12 _ 
Tap-water extract of two en¬ 
tire curly-top beets which 
had been macerated in a 
mortar. 
Two young beet 
plants. 
May 15 . 
Expressed juice of 12 young 
curly-top beets. 
Several young 
beets. 
Do . 
Expressed juice of curly-top 
plants and expressed juice 
diluted with equal parts of 
tap water. 
.do . 
Do 
do _ _ _ _ 
.do . 
July 5 . 
Parts of viruliferous leafhop- 
pers which had been anaes¬ 
thetized with ether to facil¬ 
itate dissection. 
Twenty-oneyoung 
beets. 
Season of 1921: 
May 3 . 
Juice of a curly-top plant ex- 
tracted by means of a hypo¬ 
dermic syringe. 
Seven beet plants. 
One had only 
cotyledons; the 
others had seven 
leaves. 
Method of inoculation 
One insect macerated on and 
pricked into a leaf of each plant. 
Insect first stunned by a gentle 
pressure between the fingers. 
About 500 cc. of the extract poured 
on the soil around the roots. 
Plants dug with as little injury to 
the roots as possible and roots 
placed in extract for one hour; 
older leaves then removed and 
plants replanted. 
Roots placed in the extract for one 
hour; older leaves then removed 
and plants replanted. 
Tissue placed in a slit in the petiole; 
wound not covered. 
Tissue placed in a slit in the hypo- 
cotyl; wound covered with soil. 
Insect forced into a slit in the peti¬ 
ole of the plant; wound bound 
with doth and grafting wax. 
Insect pressed into a slit in the 
hypocotyl; wound wrapped and 
covered with grafting wax. 
One insect in a slit in the crown of 
each plant just below the ground 
level. 
Tissues placed in a slit in the root 
just below ground level; wound 
covered with soil. 
Roots allowed to stand in extract 
over night; leaves then removed 
and roots replanted. 
Healthy leaves cut and cut ends 
placed in vials of the extract; non- 
viruliferous leafhoppers placed 
on these for two days and then 
on healthy beets. 
Slowly injected through fine glass 
nozzles attached to a funnel con¬ 
taining the extract, which was so 
elevated as to cause a gentle 
pressure of the liquid. 
Cut ends of petioles of healthy 
leaves placed in vials of the ex¬ 
tract; seven nonviruliferous in¬ 
sects were then caged on the 
blades of these leaves for three 
days and then transferred to 
healthy plants. 
Plants dug and roots allowed to 
stand in the juice for four hours 
and then replanted. 
Roots placed in the two solutions 
for four hours and then replanted. 
Cut ends of petioles of healthy 
leaves placed in vials of the ex¬ 
tract and nonviruliferous insects 
placed on them for four days and 
then transferred to healthy beets. 
Parts of insects (e. g., heads, thorax, 
» and abdomen) were placed in 
Ringer’s solution, then on each 
plant an insect part was inocu¬ 
lated into the base of the blade of 
each of the first true leaves by 
means of a sharp steel needle. 
Juice slowly injected by means of 
hypodermic syringe immediately 
after it was extracted from 
diseased plant. Injected into 
crowns and cut end of a petiole. 
