1236 
Literature 
Bulletins 190, 218, California Experi- 
ment Station. 
Gray Mold 
Botrytis vulgaris 
This produces a dark-colored decay of 
the rind, on which a dirty gray mold de- 
velops. The fungus is able to develop 
at low temperatures close to the freezing 
point, and sometimes causes considerable 
loss in fruit held in cold storage. Not 
ordinarily very serious. 
Lemon Gummosis 
Characterized by the exudation of gum 
from the trunk of the tree just above the 
point of budding. The tree appears yel- 
low and dies when badly affected. Oc- 
curs on poorly drained, heavy soil, espe- 
cially if the point of budding is deeply 
covered with earth, and where the soil 
about the trunk is undisturbed by culti- 
vation. This trouble is more common on 
lemons than on oranges. 
In order to successfully control gum 
diseases in orchard trees, soil conditions 
must first of all be improved by securing 
drainage, removing soil from about the 
bud and thoroughly cultivating or dig- 
ging about the tree. Water must not be 
allowed to stand about the trunk or the 
soil remain continually saturated. After 
thus improving conditions, the tree itself 
may be treated by taking out narrow 
slits of bark on several sides of the trunk, 
extending from the ground up to the 
fork. These slits should pass through 
the gummy portion and also the unaf- 
fected bark. This will usually suffice to 
effect a cure if taken in time and if soil 
conditions are sufficiently improved. 
Literature 
Bulletins 200, 218, California Experi- 
ment Station. 
Red Rot 
A. curing-house trouble in which the 
rind develops a rusty bronze color and 
gradually dries down into a sunken con- 
dition with a dark red or black color. 
Cause unknown; apparently not a para- 
site. 
Peteca 
This trouble shows itself in the form 
of deep sunken pits in the rind of the 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
lemon after it has been in the curing 
house for some time. The tissue at these 
spots is found to be dried and shrunken 
prematurely. The trouble is not serious, 
save in its effect upon the appearance of 
the fruit. Cause unknown. 
Wither-Tip, “Tear Stain” 
Colletotrichum gloeosporiordes 
The effects of this disease consist in a 
general way in a spotting of the fruit and 
leaves and killing back of the twigs, and 
an attack upon the young, newly-formed 
fruit, causing it to drop. Wither-tip is a 
trouble of quite common occurrence in 
Florida and probably most other citrus- 
growing regions. It has been known to 
exist in California for some time, but 
there has always been a question as to 
how much this fungus is really parasitic 
and how much it develops simply in a 
secondary manner upon tissues injured 
in other ways. 
The most pronounced effect upon lem- 
ons attributed to the wither-tip fungus 
has been a slight spotting of the fruit, 
the spots being quite numerous upon the 
exposed side of the lemons while still 
on the tree, each spot of small size and 
reddish color. Such spotting has been 
quite generally attributed to this fungus, 
and yet it may be said that in numerous 
efforts made to produce such an effect 
by direct infection with the spores of the 
wither-tip fungus, entire failure has al- 
ways been the result. 
The fungus commonly shows itself to 
the eye in the form of numerous minute 
black dots upon the surface of dead twig 
tips or on dead spots on the leaf. In the 
latter case, starting on spots killed by 
fumigation, fire or other injuries, or pos- 
sibly without preliminary injury on old, 
nearly dead leaves, the spots slowly 
spread in an oval form, with a yellow 
band between the dead and green tissue 
and the characteristic black dots (pycni- 
dia) upon the surface of the dead por- 
tion. 
Another fungus, a species of Pleospora, 
having a similar appearance and effect, 
has also been found quite abundantly on 
citrus trees in the northern part of the 
state. 
