CUCUMBER DISEASES 
Anthracnose 
Colletotrichum sp. 
Anthracnose occurs on the leaves and 
stems of cucumbers and muskmelons, 
and on the leaves, stems, and fruits of 
watermelons. It also attacks other cu- 
curbits. It is common and sometimes 
injurious. 
Appearance 
Circular dead spots from one-fourth to 
one-half inch in diameter are formed on 
the leaves. On the stems anthracnose 
causes elongated, discolored, and shrunk- 
en areas, which finally lead to the death 
of the branch. Watermelon fruits are 
often badly spotted by this disease, and 
much injury is done to the vines. 
Cause 
Anthracnose is due to a fungus which 
is related to the fungi causing anthrac- 
nose in grapes, raspberries, cotton, and 
beans, and the bitter rot of the apple. 
It is spread freely by the fruiting bodies, 
which are produced in abundance in the 
spots on the leaves and fruit. The de- 
struction of such vines, together with 
rotation of crops, is recommended as a 
means of prevention. 
BuieHt. See Downy Mildew, this sec- 
tion. 
Cucumber Rot 
Cucumbers in Florida have been 
troubled with a disease which attacks 
both leaves and fruit. The plants may 
be attacked when very young. There ap- 
pear on the leaves irregular water-soaked 
spots. The leaf becomes dwarfed and 
misshapen if the disease strikes it when 
young. If the sun is hot during the day 
the spots dry up, leaving a brown area, 
which will fall out. Quite often the in- 
fection starts along the edges of the 
leaves. The veins become affected, and 
it appears as if the disease follows the 
veins. Early in the morning, if one 
should examine the under side of the 
leaves, he would find underneath each 
spot a drop of bacterial ooze. Later in 
the day this dries, giving the appearance 
of a white precipitate. The spot on the 
cucumber fruit is small, about two milli- 
meters in diameter. At first it is a trans- 
855 
parent area, then in the center there ap- 
pears a small white spot which is the 
dried bacterial ooze on the surface. If 
one should cut through an early spot, 
he would find only a water-soaked area. 
Later this area turns brown. This brown 
area, spreads along the vascular bundles 
in the cucumber fruit. Three days later 
the whole cucumber is soft. 
The disease is spread over the entire 
cucumber-growing district of Florida. 
Much loss is sustained while the cucum- 
ber is on its way to market The reports 
show that while the cucumbers are on 
the way to market, which takes four to 
five days, they become soft. 
Remove affected plants from the field 
and spray with Bordeaux mixture, 
thoroughly, beginning when the plants 
have but three or four leaves. 
O. F. BurGeEr, 
Florida Experiment Station. 
CUCUMBER Scap. See Spot, this section. 
Damping Off 
This is a frequent trouble upon green- 
house cucumbers. Itis serious often where 
plantings are made following lettuce at- 
tacked by rosette. The fungus in that 
case is the same as_ lettuce-rosette 
(Rhizoctonia)* or lettuce drop (Botrytis). 
There is a strictly damping-off fungus 
(Pythium De Baryanum Hesse) that is 
sometimes troublesome. The Botrytis 
named at times attacks pruned parts of 
cucumber plants, also extending its at- 
tacks to the blossom end of young fruits. 
The results of Rhizoctonia on green- 
house cucumbers have been curious owing 
to attacks on the smaller root branches 
or rootlets. The growth of the vines is 
at times checked, accompanied by color- 
ing of the leaves and reduced fruitful- 
ness. Some growers have given the 
name “leaf-curl” to this phenomenon but 
it is strictly the effect of the fungus 
named. It has been found necessary in 
soil treatments where cucumbers follow 
affected lettuce to increase the strength 
of formalin drench to 4 or 5 pounds per 
50 gallons of water. 
A. D. SELBY, 
Wooster, Ohio. 
