Bulletin 208, Cucumber Diseases in Florida


has been applied to seedlings showing this condition. This injury
may have taken place at any time between the separation of the
seeds from the pulp and the development of the first true leaf
following the appearance of the cotyledons of the seedling above
ground. This condition results from the partial or complete
severance of the plumule in the seed or the growing tip in the
young seedling. The loss of the growing tip naturally delays the
growth of the plant. Often secondary buds develop when the
injury does not involve the whole growing tip. These buds oc-
casionally develop after a normal fashion but more often they
show only feeble and distorted growth. The seedlings thus af-
fected are darker green in color than unaffected seedlings. The
cotyledons are larger and more leaf-like, whereas if a single leaf
develops, as often occurs, it is dark green, ill-shapen and thicker
than normal leaves. It is more cotyledon-like in its general tex-
ture. Growers have often observed this type of plant and have
referred to them as "giant" plants.
 The exact cause of this injury is not definitely known but it
 seems safe to suppose that it is the result of mechanical injury
 as differentiated from any other cause. The possible mechanical
 causes may be blows or pressure applied to the seed or there
 may be attacks of fungi or insects in which the young growing
 tip of the seedling is killed or eaten. In a small planting of com-
 mercial seed on the Experiment Station grounds 3.8 percent of
 the seedlings showed snakehead. No method of control for this
 trouble is known.


 LEAF SPOTS

 There are several unimportant leaf spots occurring on the
cucumber plant which have not been found in Florida. They
have been found elsewhere but seldom known to be serious factors
except in isolated localities in northern sections of the country.
They are listed here as information, however. Cercospora citrul-
lina Cke.; Cladosporium cucumerinum E. & A.; Septoria cucur-
bitacearum Sacc.; Phyllosticta cucurbitacearum Sacc.
 A description of these individual leaf spots is not important at
this time and as for control methods, they will be taken care of in
the control measures applied for the control of downy mildew.