Apr* 21, X923 
Gummosis of Citrus 
203 
Tabl^ III .—Inoculations of Pythiacystis citrophthora on trunks of ig-year-old lemon 
trees at Santa Paula 
Experi¬ 
ment 
No. 
Part of trunk inocu- 
lalod. 
Date of inocula¬ 
tion. 
Date of observa¬ 
tion. 
Size of killed bark 
lesions. 
Gum forma- 
tion.i 
I 
30 cm. from bud 
Nov. 23, 1012 
Dec. 
30,1912 
0 
0 
union, 60 cm. 
Feb. 
12,1913 
10 
by 3-5 
3 
from soil. 
Mar. 
14,1913 
II. 
5 by 
5 
3 
Apr. 
12,1913 
18 
by 
8 
3 
2 
15 cm. above 
.do. 
Dec. 
30,1912 
0 
0 
bud imion. 
Feb. 
12,1913 
9 
by 
5 
3 
Mar. 
4 ,1913 
9 
by 
5 
3 
Apr. 
12,1913 
13 
by 
8 
3 
May 
7 ,1913 
13 
by 
8 
^ 
Jtme 
s>1913 
35 
by 
8 
2 (PI. 2, 
P,3, A) 
3 
10 cm. above 
Dec. 
30,1912 
0 
0 
bud union. 
Feb. 
12,1913 
14 
by 
5 
I 
Mar. 
14,1913 
18 
by 
5 
3 
Apr. 
12,1913 
19 
by 
6.5 
3 
May 
7 > 1913 
19 
by 
6.5 
June 
5 » 1913 
25 
by 
6.5 
3 
4 
Trunk, 13 cm. 
Feb. 20,1913 
Apr. 
i> 1913 
2 
above bud 
May 
7 » 1913 
7-5 
4.0 
3 
imion. 
June 
27,1913 
10 
by 
6 
3 
July 
28,1913 
15 
by 
8 
3 
Oct. 
23,1913 
33 
by 15 
3 
1 o*-none, i—slight, 2—medium, 3—copious. 
These typical examples show that the general development of the 
disease was the same with inoculations with pure cultures oi Pythia¬ 
cystis citrophthora as it was with the inoculation with bits of diseased 
bark or fruit previously described. A period of slow development for 
2 to 4 months is followed by copious gumming and rapid development, 
resulting in large invaded areas in 6 to lo months. Later the rate of 
increase is again comparatively slow and is frequently partially checked. 
It is believed that the accumulation of gum in the outer gummous 
zone is a material hindrance to the rapid advance of the fungus. This 
feature of the disease is discussed in Part III of this paper. 
A partial representative list of inoculations from which Pythiacystis 
citrophthora was again isolated, with the date and the size of invaded 
areas at time of isolation, is shown in Table IV. 
TablB IV .—Representative inoculations of Pythiacystis citrophthora 
Date of inoculation. 
Date of reisolation. 
Size of invaded 
area. 
Nov. 16, 1912 .. 
Nov. I, 1012 ... 
Cm, 
23 by 10 
46 by IS 
47 by 8 
35 by 8 
25 by 6 
95 by 46 
33 by 13 
48 by IS 
IS by S 
25 by 8 
8by s 
30 by 10 
46 by 13 
30 by 
Do . 
Tulv 10, loi^ . 
Nov. 23, 19x2 . 
Aor. 12. loii . 
Do . 
Tune <, 1012. 
Do. 
j ■‘■y •*■0 *.. 
.do. 
Feb. 26, 1913. 
Feb. 7. loi'?. 
Do . 
Oct. 22, 1913 . 
Tlllv fZ. TOT'J. 
May 9, 1914 . 
j nxjf xyxj..... 
Sept. TO, T914 . 
Oct. 0. 1014 . 
Oct. T4, T9T4 . 
Aor. 7, iQi< ..... 
Feb. ' 7 . TOTt. 
Scot. 2. loit; . 
'-v. f , xyx^.... 
Mat- /j, T9I5 r - - T r T f - - t - T - - t. 
.do. 
T)o. 
.do. 
Atir. 0. totc.. 
.do... 
xyx^....... ................ 
