204 
Journal of Agricultural Research 
Vol. XXIV No. 3. 
As is shown by Table IV, the fungus was recovered in different cases- 
from I to nearly 12 months after inoculation and from margins of different 
invaded areas varying from 8 to 95 cm. in vertical extent. Since the 
fungus was isolated most frequently at the upper margin of the invaded 
area, the distances from the original point of inoculation at which the 
fun^s was recovered was frequently more than one-half that of thia 
vertical extension, because the areas usually enlarged upward much 
faster than downward or laterally, as previously pointed out. 
The severe inoculation test to which this fungus was subjected in order 
to establish its causal relation to this type of gummosis is indicated by 
an example of the repeated isolations, inoculations and reisolations of 
one of the strains of this fungus, over a period of three years. Isolated 
in September, 1912, its record was as follows: 
Date of inoculation. 
Date of reisolation. 
Size of lesions. 
Nov. 22, 1012 . 
Aor. 12 . IOT 2 . 
Cm. 
47 by 8- 
48 by IS 
46 by 13 
Tune 12, 101“?.. 
Mav 0. IOTA.. 
Mar. 4, ioi<;. 
Scot. 2. 10 TC. 
AVAwwA * ^0••••••••••••••••••••••• 
.... • 
The fungus was thus in the bark of the three trees for periods of about 
5, II, and 6 months, respectively, and between these periods in cultures, 
for about 2, 2, and 10 months, respectively. Transfers from the original 
culture which were kept alive for over 8 years, on commeal-agar 
medium, were still capable of producing brownrot of lemon fruits when 
tested in 1921. 
INOCULATIONS WITH PYTHIACYSTIS CITROPHTHORA ON DIFFERENT PARTS OF SAME TREES. 
After the results of the first inoculations began to indicate that 
Pythiacystis citrophthora was the causal agent in this type of disease, it 
became important to find out the effect of the fungus when introduced 
into different parts of the same tree. Inoculations were made on roots,, 
trunk, and branches of various ages, as shown in Table V. 
Table V .—Inoculations with Pythiacystis citrophthora July 13,1913, at different locations 
on same tree 
Part of tree inoculated. 
Length and width of killed bark areas. 
X913 
July 27. 
Sept. 13. 
Nov. 25. 
1914 
Apr. 9. 
May 9. 
Pinal extreme 
distance from 
place inocu* 
lated. 
ward. 
Down¬ 
ward. 
Large root (sweet-orang< 
stodc), Z3 cm.below bud 
union (PI. 4, B). 
Orange bark of stock s cm. 
below bud union (PI. 3, 
D).. 
Lemon trunk, 13 cm. 
above bud union (PI. 4, 
B)... 
Lemon trunk 88 cm. 
above bud union just 
below crotch. 
Limb 8 cm. in diameter... 
Limb 5 cm. in diameter... 
Limb 5 cm. in diameter... 
Limb 2.5 cm. in diameter.. 
Limb 3 mm. in diameter.. 
Controls, not inoculated... 
Cm. 
2.5 by 1.8 
4 by 1.8 
5 hy 2.5 
2.5 by o. 6 
2. s by o. 6 
Cm, 
Cm. 
ro by 2.5 
2S by 10 
13 by 4 
20 by 6 
10 by 5 
IS by s 
o 
24 by 10 
50 by 25 
34 by 9 
33 by 8 
30 by s 
27 by 1.3 
10 by 5 
18 by 5 
o 
Cm. 
13 by 4 
43 by 13 
53 by 25 
36 by 9 
33 by 8 
30 by 5 
30 by 2. s 
IS by 5 
22 by 5 
o 
Cm. 
14 by 5 
48 by IS 
68 by 2S 
36 by 9 
33 by 8 
30 by s 
30 by 2.5 
isby s 
22 by s 
o 
Cm. 
9 
40 
46 
Cm. 
13 
12 
XO 
5 
7 
o 
