DEPARTMENT OF AGRICULTURE 53

upward through the vascular portion of the plant. This disease
has also been observed in areas of the state, however, the
disease has not become serious. There are also wilt resistant
lines such as Oxford 26 and other new varieties are being
tested.
 Frogeye and Brown Spot: Are most common on tobacco that
is approaching maturity. The two diseases are caused by
different organisms. However, their presence on the leaf has
not reduced the buyers acceptance because it is a good indi-
cation that the tobacco is ripe. No control measures are known.
 Southern Stem or Stem Rot: This disease does not usually
affect more than 10 per cent of the plants. Affected plants will
wilt and die suddenly because the disease attacks the stem
at the ground level and the decay extends into the root.
 Viruses: The potential danger of this disease appears to
be greater than many others because tobacco is a very sus-
ceptible host to many virus; such as common mosaic, ring
spot, etch, vein banding, and streak.

 Several of these viruses have been known to be transported
into the production area from tobacco plants produced in the
southern part of the state. Not all southern areas are infected;
however, the multiplicity of natural host and the susceptibility
of tobacco lends importance to this disease. Many of the virus
infected plants cannot be identified until the plants have been in
the field five to six weeks. Then it is too late to begin re-
planting. There are varieties of tobacco that are tolerant to
many of the viruses; however, Florida growers should be on
guard to help prevent the establishment of a virulent disease
within the production area.

 Other diseases: There are many more diseases which attack
tobacco and only the more important ones will be mentioned,
namely, Fusarium wilt-tobacco should not be planted after
sweet potatoes in Florida. Sore shin, hollow stalk and brown
root rot are diseases of minor importance as the casual or-
ganism, are often found only in small areas.
 Injuries:

 (1) Drowning, if water stands or the soil becomes water
logged, tobacco plants flop or leaves will droop instead of
remaining erect, roots lack oxygen and die.