Florida Agricultural Experiment Station


year so that the possible source of inoculum is always present and
all that is necessary for its spread is carrying agents.
 Description: In general the two characteristic symptoms of
 mosaic are a definite green mottling of leaves and fruit and a
 marked stunting of the vines. These symptoms vary somewhat
 according to the age of the plant at the time of infection. The
 disease is not often found on the cucumber in the extreme early
 stages of its development. In Florida the disease has manifested
 itself about the time four or six true leaves are formed. The
 younger leaves show a distinct mottling of dark and light green
 color, a sort of patchwork over the leaf. In other respects the
 leaf appears quite normal, except that it is reduced in size.
 As the plant grows older the new growth at the ends of the
 runners does not develop normally but rather appears rosetted
 and stunted, the internodes are shortened and the leaves are
 much smaller and more deeply notched. The older leaves near
 the base of the vine begin to yellow and droop, gradually dying,
 in the last stages there remain only a few small green leaves at
 the extreme growing tips of the runners. (Fig. 21.) The dis-
 ease shows up early on the fruit of mosaic plants. The mottling
 is quite similar to that described on the leaves and in severe in-
 stances the fruits become distorted, rough and warty. These
 fruits are not marketable because of their appearance. (Fig. 22.)
 Control: Attempts at breeding or selection of resistant plants
 have been unsuccessful. Eleven genera and 26 species of plants
 closely related to cucumbers have been found susceptible to
 mosaic.
 Field sanitation has been successfully practiced in certain dis-
 tricts by cutting all weeds showing the symptoms of mosaic, thus
 removing the source of infection. This practice has given good
 results and will probably prove to be the only way to control the
 disease in Florida should it become severe.
 Whenever mosaic plants are found they should be pulled up
 carefully and removed from the field. The hands should be
 washed thoroughly in a disinfectant before healthy vines are
 again touched. Pickers should be cautioned about the danger of
 spread of the disease and be taught to avoid the diseased plants
 in the field.
 Another method of control is the elimination of insects that
transmit the disease. This can be done on a small scale but is an
expensive operation and would probably not be profitable in large
fields. The disease is not carried on or in the seed and no evi-