32 
FLORIDA STATE HORTICULTURAL SOCIETY 
quickly absorbed by certain chemical con¬ 
stituents of the soil called colloids. The 
scarcity of these compounds in the sandy 
soils of the Fort Pierce section probably 
accounts for the comparative effective¬ 
ness of the small dose mentioned above. 
It is probably this absorption by these 
colloids which is responsible for the poor 
results we have obtained when we applied 
the material in solution. The top layer of 
the soil absorbs the material and the ne¬ 
matodes in the deeper layers escape. The 
same results followed when all of the 
dosage was applied as a top dressing to the 
plowed land and then disked in. It is 
therefore, necessary to mix the material 
with the soil as thoroughly as is practica¬ 
ble. Under farm conditions it would 
seem that this is best accomplished by 
spreading rather more than half of the 
amount on the surface, plowing it under 
as deeply as possible, and then adding the 
remainder and disking it thoroughly. This 
is the method we have found most success¬ 
ful on our plots. A more uniform distri¬ 
bution can be obtained with a fertilizer 
spreader, as a uniform distribution is very 
important. We strongly recommend the 
use of one. In some cases when we could 
not get the land plowed as deeply as we 
wished, we have followed the plow with 
a bucket of cyanamid and sprinkled it in 
the bottom of the furrow. On a small 
garden plot it is practical to have it hoed 
or spaded in, thus securing a more even 
distribution. It is best to choose a dry 
time for the application as the material 
will mix better with dry earth. In wet 
ground it tends to form lumps as it ab¬ 
sorbs water readily. If stored for some 
months, particularly during the rainy sea¬ 
son, cyanamid absorbs water from the air 
and forms hard lumps. These must be 
broken up before the material can be used. 
All cyanamid used for this purpose should 
be sufficiently fine to pass through an 18- 
mesh wire mosquito screen. Chunks of 
the material, added to the soil, not only are 
useless for killing nematodes, but they 
remain in the soil for a long time before 
they entirely disintegrate, and have a very 
harmful effect on subsequent plant 
growth. When fresh, the material is a 
very fine powder which works well. 
When the material has been thoroughly 
mixed with the soil, the field should be at 
once irrigated. Enough water should be 
used to thoroughly wet the soil to the 
depth ordinarily reached by nematodes, 
which is 15 to 18 inches in the usual loose 
sandy soils of our State, or to ground 
water. Although the great bulk of the 
worms are in the first 8 or 9 inches of 
soil, it is necessary to kill the few below 
that depth otherwise the latter will in a 
few weeks, restock the upper layers of 
soil. This thorough irrigation is very 
important for at least two reasons. It 
completes the distribution of the cyanamid 
commenced by the plow and disk harrow 
so that more of the nematodes are reach¬ 
ed and killed and it hastens the decomposi¬ 
tions of the cyanamid, shortening the time 
that must elapse before the crop can safe¬ 
ly be planted. Although a heavy rain im¬ 
mediately after application is equivalent 
to an irrigation, we do not advise the use 
of the cyanamid metheod of dealing with 
nematodes except on land that can be ir¬ 
rigated. One cannot safely depend upon 
the weather, and the material is too costly 
to lose. 
