6 Florida Agricultural Experiment Stations

 The influence of crop rotation on tobacco production has been
reported by a number of workers, and it was found that certain
weed and crop plants were more beneficial than others. Godfrey
(17) listed many crop plants that were immune or highly re-
sistant to root-knot. However, Graham (18) and Steiner (23)
reported later that corn and peanuts are hosts for nematodes.
These crops are often grown preceding tobacco. Bratley (1)
has reported many native weeds to be hosts for nematodes.
Clayton et al (4,5) reported six primary root diseases which
effect tobacco and found that similar cropping practices do not
work equally well for all diseases. They also found an effective
nematode control by using Spanish peanuts, oats or rye in rota-
tion. Allowing the land to grow to weeds for two years or more
was found to be very helpful, but less profitable than growing
a cultivated crop. It was also found that a winter cover crop
of oats or rye turned under increased the value of tobacco about
$50 per acre. These workers ntuted finuther that growers may
use crop rotations for disease control in two ways: (1) Wait
until the field becomes seriously diseased and then rotate crops,
or (2) observe disease developments more closely and practice
rotations with a view to keeping the tobacco soils relatively dis-
ease free.
 Valleau (25) stated that the burley tobacco industry was de-
veloped on sod-tobacco rotations. However, recent develop-

Fig. 4.-General view of irrigation plots with irrigation system in place.






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